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1771-6.5.25, Servo positioning Assembly User Manual

1. PLC 2 30 A 1772 SD2 80 E D E 10 000ft System Chassis 1 Chassis 2 Fu Wn Tw m L m A IH wW TI n wW n W wW n n LI IH 1771 AS 1771 M3 1771 ES 1771 AS 1771 M3 1771 ES Chassis 3 Chassis 4 Hu Q Ja td cj C313 jen Ill ji n v E i Lyk ak 1771 AS 1771 M3 1771 ES 1771 AS 1771 M3 1771 ES 11058 Chapter 8 4 Calculate worst case time between write transfers Since each chassis contains one block transfer module each 1771 M3 controller is serviced once every four remote I O scans Because the 1771 M3 controller module uses bidirectional block transfer a read transfer occurs between consecutive write transfers Consequently a write transfer for a given 1771 M3 controller occurs every eight system scans In those eight scans four write and four read transfers occur Time Between Write Transfers 4TW ATR 4 123 4 87 840ms PLC 2 30 Local System In a PLC 2 30 local system all block transfer modules are serviced once in each system scan Time be
2. Figure 2 2 Closed loop Axis Servo System Axis Motion Motor Encoder Velocity Feedback Command Position Data Velocity Status dc Command Block Processor e Seno T Drive L Drive Disable Tach Input for Loss of Feedback P z Detection Position Feedback 4 E m Discrete Inputs Forward Servo Controller Servo Expander cat no 1771 cat no 1771 ES NOTE A second and third Servo Expander Module could be installed in this I O chassis for control of a second and third axis Jog Reverse Home Limit Switch Hardware Stop Hardware Start Feedrate Enable Discrete Output L Hardware Done 10998 The PC processor sends commands and user programmed data from the data table to the 1771 M3 controller as directed by a block transfer write instruction The 1771 M3 controller coordinates the block transfer automatically keeping ladder diagram programming to a minimum Based on information it receives from the processor the 1771 M3 controller sends axis motion commands to the 1771 ES expander The 1771 ES expander closes the servo
3. SWOH ezi eniu ep Sess opes Command Block Illegal Command Combinations Table 7 D sls 2 v ols i gje X S o E BIS 2 ol D Dp Qs 5 2 2 g S 2 L 2 g O c2 5100 E 5 6 sls o ola 5151 N 2 ol gt 1218 11 o vo 515111110 5 5 gt o 2 S 5z lzleiei sizisSiel9 S al9 5 3 31 2 2 2 Slols 2 2 l 5 lt z s 9 S g O 2 5 8121515 z 20 01215 5 0 52 2 20 61212 lt 2 2 pEESUC UNES oO am D D o A E Cc D 5 pum e LL L c o 7 78 Chapter 7 Formatting and Interpreting Data Blocks Here are some additional notes about illegal programming Even though the programming error bit in the status block is on the 1771 M3 controller responds to the following commands and information emergency stop slide stop eset software travel limit override tachometer calibrate feedrate override value jog rate select f you issue a preset new parameter or initialize home command while the axis is in motion the status block indicates a programming error If the comman
4. oN CHA ZI Diff n CH B ifferential 4 Output XX CHB 5 z Encoder Marker BI Marker z E 9 Q Belden 8725 or Ground the shield 1o equivalent at the I O chassis end 50 ft max MIC Has Connecting a Single Ended Encoder Left Wiring Arm of 1771 ES Expander 12020 Figure 6 11 shows details of how to connect a single ended encoder Connect each channel return line to common 6 20 Chapter 6 Installing the Assembly Figure 6 11 Connection Details for a Single ended Encoder 5 to 30V DC Belden 8761 or joa 60 nae customer oe max E supplied Ground the shield d at the I O chassis end Y CHA Q Single Fs CHB M 3 Output D Encoder CH B 6 L Marker S r T 8 I Belden 8725 or Ground the shield 0S equivalent at the I O chassis end 27 50 ft max 11 Has Left Wiring Arm of 1771 ES Expander 12 If you switch channel with channel B you reverse the direction of the feedback If the direction of the feedback does not correspond to the axis motion direction as you have defined it switch channel A with channel B Ground the shield at the I O chassis end Connecting the Analog Output Supply
5. Word 4 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 8 Axis 2 Word 12 Axis 3 i ar EE Command Taken Diagnostic Valid EM Mors UTEM Position Valid Following Loss of Power Error Valid Programming Error Axis Fault Block ID 11054 Bit 0 5 Move Number These bits indicate the active move within the moveset in BCD format Bit 6 Loss of Power When set this bit indicates a loss of power across one of the following sets of terminals terminals 1 and 12 input supply of the left wiring arm terminals 1 and 6 analog supply of the right wiring arm If this bit is on then the immediate stop bit in the status block is on indicating that immediate stop has been executed after detection of the loss of power Bit 7 Programming Error If the 1771 M3 controller detects an illegal bit combination such as a non BCD value where one is expected or an illegal bit combination in the command block it turns on the programming error bit When this bit is on bits 10 thru 12 of this status word provide a code to identify the block containing the programming error 7 11 Chapter 7 Formatting and Interpreting Data Blocks 7 12 When you detect that this bit is on you may want to turn on bit 11 of axis control word 2 in the command block to display diagnostic status in the 3rd and 4th status words for the axis Bits 12 11 10 Block ID These bits are the b
6. Data table address of first moveset block to be transferred for axis 3 BCD format 11032 Chapter 7 Formatting and Interpreting Data Blocks Important The address pointer value you enter in each of these words must be a BCD value other than 000 For each axis include only the address of the first moveset block in the parameter block Include address pointers to subsequent movesets in the blocks that precede them If you program an escape move you must enter its address in the parameter block moveset address pointer word You must do this because the escape move must be the first moveset transferred to the 1771 M3 controller even though it is not the first moveset normally executed Feedback Resolution Feedback resolution is the smallest unit of axis motion that can be distinguished by the servo positioning assembly That is it is the distance the axis moves per feedback increment Enter the value of feedback resolution in the feedback resolution word of the parameter block Figure 7 11 As described in chapter 3 feedback resolution is determined by the number of encoder lines the feedback multiplier and leadscrew pitch Feedback Resolution Axis Displacement per Encoder Rev Encoder Lines Feedback Multiplier If the system has no gearing the axis displacement per revolution is the same as the leadscrew pitch or lead Figure 7 11 Feedback Resolution Word Feedback Resolution Word 7
7. 4 2 lil POSON sz axes ERR ws E Ex PES 4 8 Synchronizing Axes 4 8 Specifying Axis Position 4 10 zur er oremi niei nE i 4 13 Hardware Description 5 1 Chapter Objectives 54 liec 5 1 Inputs Outputs 5 2 External Power Supplies 5 7 Compatible Processors 5 8 Fault Responses 5 9 Specifications iie RE _5 11 SUMMA 5 1 Table of Contents Installing the Assembly Chapter Configuring the Modules Setting Switches and Jumpers KeyIng oss Ghats HIER EURO Inserting the Module Connecting to Terminals Connecting Encoder and Drive Start up Sequence GUMMA Me cisean eiti detn anida bais nik nE Formatting and Interpreting Data Blocks Chapter Relationship of Data Blocks
8. Status Block Parameter Block 00 c cece cece eee eee Moveset Block Command Block Summary Chapter Programming Objectives PLC 2 Family Block Transfer Instructions PLC 2 Family Block Transfer Timing PLC 3 Block Transfer Instructions PLC 3 Block Transfer Timing Programming Example SUMMA Integrating Axes Chapter Objectives sc uds eser Re UR IRR Open Loop Procedure Closed Loop Procedure Tachometer SUMMA PT Em Troubleshooting Chapter Objectives Monitoring 1771 M3 Controller Indicators Monitoring 1771 ES Expander Indicators Monitoring the Status Troubleshooting Flowchart SUMMA Ex a Ead Sees D
9. nm me E ON ON OFF ON OFF OFF Set one switch to ON to select that axis number Set the other two to OFF 12016 Set to on the switch corresponding to the number for the axis Set to off the other two switches in the assembly Set each 1771 ES expander in an I O chassis to a unique axis number starting with 1 Selecting Encoder Input Polarity Select the polarity of each encoder input to allow your encoder to function properly with the 1771 ES expander Figure 6 1 Encoder Polarity Jumper Position High true Low True Left Right Keying Chapter 6 Installing the Assembly With a differential encoder the connections and the polarity jumper positions determine the polarity of the feedback signals With a single ended encoder the polarity jumper positions alone determine the polarity of the feedback signals The polarity selections are important to the marker logic Set the polarity so that the marker is true at the same time that channels A and B are true refer to Figure 3 7 Selecting Encoder Input Signal Mode Select the signal mode of each encoder input to match the encoder Figure 6 1 Encoder Signal Mode Jumper Position Single ended Left e e Differential Right e e Selecting Marker Logic For almost all encoders set the marker logic jumper to
10. 4 Positioning with Allen Bradley moves at the final velocity some distance decelerates to zero velocity at which time it has reached the programmed endpoint Move Values Each move block can specify several values The servo positioning assembly executes the move based on these items you enter endpoint acceleration final feedrate deceleration When you select a deceleration value the 1771 ES expander automatically calculates the point at which the deceleration must begin You can combine several single moves like that of Figure 4 5 to form a moveset Figure 4 6 shows an example that consists of four moves Move starts at position coordinate 0 and ends at position coordinate 2 Move 2 continues axis motion to position coordinate 5 Move 3 continues to position coordinate 7 Move 4 then causes the axis to reverse direction and move back to position 0 The axis stops after it returns to its initial starting position A drawing like that of Figure 4 6 is a moveset profile You can use such profiles as an aid in programming axis motion Figure 4 6 Moveset Profile with All Single step Moves m Move 1 Move2 Move3 Rate 0 1 2 3 4 5 6 7 8 Position Rate Move 4 11011 4 5 4 Positioning with Allen Bradley PC You can program multiple movesets for a given axis Move Selection For each move you have each of t
11. 12022 1 Connect the hardware done output from terminal 7 on the right wiring arm to an input terminal of a dc 12 24V Input Module cat no 1771 IB 2 Connect the analog and hardware done output power supply common to the 1771 IB input module common terminal This power supply provides the 15 dc source for the hardware done signal Examine the hardware done signal thru the ladder diagram program You can synchronize the motion of several axes after each halt move send a hardware start signal to all axes when you have received the hardware done signal from each axis 6 23 Chapter 6 Installing the Assembly Connecting Drive Disable Figure 6 13 shows details of how to connect drive disable for two basic types of configurations Some servo drives require a current source connected to an input to enable the drive Some require a current sink connected to an input to enable the drive We provide all three connection points base emitter and collector of the drive disable circuit to provide you with a flexibility of connecting it in a configuration that applies to your servo drive Figure 6 13 Connection Details for Two Basic Drive Configurations a Current Sourcing Configuration 8 Drive Enable Q1 on Current is sourced bd from terminal 10 into the servo drive 8 2k Drive Disabled Q1 off Current into the servo drive is inhibited Customer s Drive
12. i i ae a 1 Get New ti uk m Preset Value t 95 Feedrate Override 1 Tachometer Binary format Calibrate Search Home Direction Jog Rate Select 0 Low 0 1 ed 1 Axis Feedrate Manual Mode Only Override Enable Readout Select 1 Software Travel 0 0 Position Limits Override 1 0 Error 1 Return to Position 9 Diagnostic Manual Mode Only Most Significant Position Preset Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 0 e inch oc dc 1 23 Most significant digits BCD position preset value 999 9999 inches or 19999 99 mm max Least Significant Position Preset Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 metric Least significant digits E 2 Symbols and D A Voltage 7 32 Empty 2 4 3 1 4 4 4 5 4 6 4 7 4 8 4 9 4 11 A absolute positioning 4 6 acceleration 4 5 Address pointers 7 5 7 19 analog supply 5 8 Applications 2 2 auto position correction 5 10 auto positioning correction 4 10 Axis Motion concept 3 1 Axis number selection 6 6 Backlash takeup 7 36 Block Transfer Instructions 8 13 Block Transfer timing 8 14 Block transfer instructions 8 3 Block transfer timing _8 6 C Channel Phase Relati
13. Troubleshooting This chapter describes the LED indicators on the 1771 M3 controller and 1771 ES expander modules It also presents a troubleshooting flowchart The flowchart provides a logical sequence for evaluating servo positioning assembly condition Used in conjunction with the indicators and the status block it can help you detect problems in servo positioning assembly operation The status block provides continually updated information about axis and servo positioning assembly conditions Refer to chapter 7 section titled Status Block p 7 4 for a detailed description of the status block The servo controller module has three indicators Figure 10 1 Figure 10 1 1771 M3 Controller Indicators PEN SERVO CONTROLLER IT Processor Communication Fault Red I Expander Communication Fault Red Active Green Processor communication fault PROC COMM FAULT This red indicator is normally off It turns on to indicate a communication fault between the PC processor and the 1771 M3 controller Such a font could be caused by hardware or by a data block overlapping a Chapter 10 Troubleshooting 10 2 processor work area or starting less than 64 words before the user program area If a hardware fault is detected at power up both the processor communication fault and expander communication fau
14. Velocity Error Velocity Command Velocity Feedback 12000 Whenever the velocity deviates from the commanded velocity the velocity feedback signal adjusts the velocity error signal until the velocity matches the velocity command signal Axis ES Feedrate Following Error Position Command Position Position Following Command Error Chapter 3 Positioning Concepts Positioning Loop When we want to move the slide a specific distance we can turn the motor on at a specific velocity for a specific length of time However this could produce imprecise positioning To accurately control the position of the slide we need a positioning loop Figure 3 3 Figure 3 3 Velocity Loop and Positioning Loop Axis Motion res Encoder AN f SS Tach 9 C Amplifier Velocity Command Position Velocity Feedback P Incremental Position Feedback 12001 The positioning loop includes a summing point an amplifier D A converter and an incremental digital encoder to produce a position feedback signal The axis feedrate is integrated in a register to produce the position command value Incremental position feedback is integrated in a register to produce the actual position value The position value is subtracted from the posit
15. olei e g e N ko N o Co PO N LI NAREN EERE IN N N co Li ie 62 g im AB 1 nd o T lids i h h e NIB Ido gt Table of Contents iii GIOSSONY iussus ada wa RR Re _ 1 Status Block 4 4 na unn _ 1 Parameter Block C 1 Moveset Block 6 1 Command Block _ 1 Manual s Purpose Audience Vocabulary Using This Manual This manual shows you how to use the series B Servo Positioning Assembly cat no 1771 QC If you have a series A Servo Positioning Assembly refer to publication 1771 817 To use the servo positioning assembly you must be able to program and operate an Allen Bradley PC processor In particular you must be able to program block transfer instructions In this manual we assume that you know how to do this If you don t refer to the appropriate manual for the PC processor you will be using Consult our Publication Index publication SD499 for a list of our publications Some inconsistency exists throughout industry in the nomenclature used for components of closed loop servo
16. Next Moveset Pointer If Required 6 1 Chapter 6 Moveset Block Moveset Control Word MCW 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 0 0 0 Inch EE Tz Metric Number of moves 1 Endof BCD format program 0 Data valid 1 Escape 1 Data not valid move 0 0 1 Axis Odd Moveset 0 1 0 a 2 pad ee 0 1 1 is 3 oveset Moveset Block ID 1 0 0 Axis 1 Even Moveset 1 0 1 Axis2 Even Moveset 1 1 0 Axis3 Even Moveset Single Move Control Word SMCW 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 1 1 000 0 Single step i Lj 1 Continous A 1 Allow feedrate override this move only 0 Run 1 Halt 1 Local feedrate 0 Global feedrate 1 Local acc dec 0 Global acc dec 0 Move to Position 1 Constant Velocity 0 Move to Position with Offset 0 Preset to Position 0 Dwell SMCW ID e Most Significant Position Wor 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 A 0 absolute Most significant digits 1 incremental inch rig 1 3 BCD home position value 899 9999 inches or 19999 999 mm max or dwell time value 9999 999 s max Least Significant Position Word 17 16 15 14 13 12 11 10
17. A4 Position Readout A display of absolute slide position as derived from a position feedback device that is normally attached to the leadscrew of the machine Programmed Dwell The capability of commanding delays in program execution for a programmable length of time Read 1 To acquire data from a source 2 Block Transfer a transfer of data from an intelligent I O module to the processor data table Register A memory word or area used for temporary storage of data used within mathematical logical or transferral functions Shield A conductive barrier that reduces the effect of electric and or magnetic fields Sign The symbol or bit that distinguishes positive from negative numbers Signal The event or electrical quantity that conveys information from one point to another Significant Digit A digit that contributes to the precision of a value The number of significant digits is counted beginning with the digit contributing the most value called the most significant digit and ending with the one contributing the least value called the least significant digit Step Response The time response of an instrument subjected to an instantaneous change in input Summing Point A point at which signals are added algebraically Tachometer A precision linear DC generator used to provide velocity feedback True As related to PC instructions an enabled logic state Write 1 The process of loading information into me
18. 15V dc 200mA maximum External supply for drive disable output 4 75V dc minimum 30V dc maximum 100mA maximum Maximum Programmable Position 999 9999 inches resolution 0 0001 inch 19999 999 millimeters resolution 0 001 mm Programmable Speed 0 0001 9990 0000 ipm resolution 0 0001 ipm 0 001 199900 000 mmpm resolution 0 001 mmpm Accel Decel 9990 ipm s maximum resolution 1 ipm s 99 99 mpm s maximum resolution 0 01 mpm s Initial Servo Gain Programmable Summary Chapter 5 Hardware Description 0 01 9 99 ipm mil following error 1 mil 001 inch 0 01 9 99 mmpm mil following error 1 mil x 001 mm Servo Sample Period 2 4115 Environmental Conditions Operational Temperature 0 to 60 C 32 to 140 F Storage Temperature 40 to 85 C 40 to 185 F Relative Humidity 5 to 95 without condensation Keying Servo controller slot between 2 and 4 8 and 10 Left servo expander slot between 2 and 4 14 and 16 Right servo expander slot between 4 and 6 32 and 34 Now that you have read about the function of each input and each output you are ready to install the servo positioning assembly Chapter 6 gives you this information 5 13 Chapter Objectives Configuring the Modules Installing the Assembly The previous chapter described the hardware of the servo positioning assembly This chapter tells you how to install the servo positioning assem
19. 80 100 Ss Move3 11060 Figure 8 13 Profile of Moveset 3 for Axis 1 Move 2 Move 4 Rate Move 1 Move 3 ipm 100 Rate 100 Rate 100 80 Dec 100 ipm s Dec 100 ipm s 60 Acc 100 ipm s Acc 100 ipm s 40 O 20 Move5 2 Second Dwell Rate 15 Rate 15 X 0 ay d 2 3 4 5 6 7 8 9 1 Position 40 Dec 100 ipm s Acc 100 ipm s 60 80 Rate 100 100 Move 6 11061 8 23 Chapter 8 Figure 8 14 Profile of Moveset for Axis 2 Rate ipm 160 140 120 100 80 60 40 20 0 Move 1 we 2 Acc Dec 100 ipm s Move 2 2 Second Dwell 20 40 60 80 100 Position Inches a Move 3 11060 Planning the Data Block for PLC 2 30 For this example we assume a PLC 2 30 processor and assign the necessary data blocks to the following data table addresses Address Command Status 400 407 447 460 Moveset 1 for axis 1 700 727 Moveset 2 for axis 1 500 516 Moveset 3 for axis 1 600 642 Moveset 1 for axis 2 1000 1012 Once we have assigned data table addresses we can plan how to enter values into the parameter command and moveset blocks to achieve the desired results The most convenient way to enter values into the data table is with the industrial terminal in the hexadecimal data monitor mode Chapter 8 Figure 8 15 shows forms filled in with the h
20. 1 Disconnect power to the servo positioning assembly and servo drives 2 Remove servo drive fuses to ensure that the servo drives are disabled 3 Verify that tachometer leads are correctly connected at the servo drive The velocity feedback signal from the tachometer must be the opposite polarity to the velocity command signal WARNING The velocity feedback loop must be closed at the servo drive If the tachometer leads are reversed or if either is disconnected sudden high speed axis motion can occur which can result in damage to equipment and or injury to personnel 4 Verify that axis overtravel limit switches are operational 5 Disconnect the drive disable lead from the right wiring arm on the 1771 ES expander terminal 9 or 10 depending on type of circuit Wire one side of a normally open momentary contact switch to the drive disable terminal Wire the other side of the switch to the drive disable lead that goes to the servo drive Figure 9 2 To move the axis with the battery box you must hold this switch closed Chapter 9 Integrating Axes Figure 9 2 Connections for Open loop Testing Battery Box dr 4O0OOOOOOOO Command Return Analog Output Rees Normal wiring Analog Return disconnected from wiring arm Drive Disable Servo Expander 11065 WARNING To guard against possible injury keep all personnel clear of the axis In addition have a competent person standing by
21. 32 767 Chapter 7 Formatting and Interpreting Data Blocks Initial Gain Multipliers Bits 0 thru 13 of this word Figure 7 13 specify the servo gain for this axis at speeds below the gain break speed specified in word 10 You must enter gain values in BCD format from 0 01 to 9 99 ipm mil or from 0 01 to 9 99 mmpm mil A mil is 0 001 inch or 0 001 mm Figure 7 13 Feedrate Multiplier Encoder Lines Multiplier and Initial Gain Word Feedback Multiplier Encoder Lines Multiplier Loss of marker Initial Gain 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 9 Axis 1 Word 28 Axis 2 Word 47 Axis 3 Loss of marker Feedback detection Multiplier 0 disabled 01 2x1 1 enabled 10 x2 Encoder oe e 00 x4 Lines Initial Gain ipm mil or Multiplier mmpm mil BCD format 1 1 mil 0 001 inch or 0 001 Seo preceding millimeter word 11035 Servo gain is the ratio of axis speed to following error Gain Axis Speed Following Error Following error is the difference between the axis position commanded by the servo expander and the actual axis position indicated by encoder feedback Servo gain affects axis response to positioning commands from the 1771 ES expander module Figure 7 14 shows how different gain values affect system responsiveness The horizontal axis represents following error The vertical axis represents analog output vo
22. AIMO 8 EO O E Velocity Feedback Position y Incremental Position Feedback 3 4 12002 Chapter 3 Positioning Concepts Feed forwarding requires an additional summing point and an amplifier The axis feedrate is multiplied by the feed forward gain K2 to produce the feed forward value The feed forward value is added to the following error multiplied by the gain to generate the velocity command Without feed forward the axis will not begin to move until the axis feedrate builds up enough following error to generate a sufficiently large velocity command to overcome friction and inertia to move the axis However the feed forward value could generate a velocity command to move the axis almost immediately This immediate response keeps the actual position closer to the position command thereby reducing the following error 3 5 Chapter 3 Positioning Concepts Leadscrew Pitch Leadscrew pitch is the linear distance from one peak of the screw thread to the next A leadscrew with a pitch of 1 4 inch is shown in Figure 3 5 Figure 3 5 Leadscrew Example Showing Pitch 4 threads per inch 4 pitch in this example Pitch is 1 4 inch in this example 12003 If the leadscrew has only one thread the pitch is also equal to the lead which is the distance the axis travels each revolution of the leadscrew You
23. Allen Bradley Servo Positioning Assembly User Manual Cat No 1771 QC Series B Table of Contents Using This 1 1 Mariual s Purpose 1 1 ee REE YR ade ES Sue ST E ei 1 1 Vocabulary 2 0 ccc eee a 21 1 Manual Organization 1 2 Introducing the Servo Positioning Assembly 2 1 Chapter Objectives 2 1 What is the Servo Positioning Assembly 2 1 tS Applications iu cee eidddaeda ead a ga ERRAE coes diese 2 2 NS FUNCION ci cage toe dA EE ea Orea 2 2 lts Features ccna odes e E tee x 2 4 SUMMAN coe ie Es ten EE dey 27 Positioning Concepts 3 1 Chapter Objectives 3 1 Closed Loop 34 Leadscrew Pitch 3 6 Encoder 37 sooo ees 3 11 Positioning With an Allen Bradley Programmable Controller 4 1 Chapter Objectives 44 Where the Servo Positioning Assembly Fits In 41 Independent of I O Scan 4 2 Move Moveset
24. CNTL DATA 0050 0001 DN LENGTH 0 15 FBO55 0000 oyyy WB055 0000 13 L 17 BTW T BLOCK XFER WRITE RACK 003 B GROUP 0 MODULE 1 HIGH CNTL DATA FD050 0201 LENGTH 0 05 CNTL 055 0000 CNTL ER 03 Rung 1 Rung 2 Rung 3 8 39 Chapter 8 Summary Rung 1 Rung assures transfer of the parameter block at power up This rung examines the ready bits WD050 0003 02 and WD050 00007 02 in the status block The parameter block address pointer 101 is stored in the second word 102 of the parameter block At power up the parameter block automatically transfers to the 1771 M3 controller If the parameter block is valid the 1771 M3 controller turns on the ready bits WD050 0003 02 and WD050 0007 02 in the status block thus inhibiting rung 1 Rung 2 If both axes are ready bits WD050 0003 02 and WD050 0007 02 both on this rung moves the address pointer in the second word of the status block WD050 0102 to the control file addresses word WB055 0004 for the write block transfer instruction The address pointer in the status block contains the word offset for the parameter command or a moveset block as requested by the 1771 M3 controller when the write block transfer instruction is executed Rung 3 Rung 3 controls both the block transfer read and the block transfer write The examine on instructions for the done bi
25. Command Combination Axis Motion Single Step Axis decelerates at the programmed rate for move 1 It reaches Run zero velocity at the programmed endpoint for move 1 Immediately after stopping the axis begins executing move 2 Single Step requires the axis to be at zero velocity at the programmed endpoint Run allows the axis to start executing move 2 without waiting for a go command in the motion control block Compare moves 3 and 4 continuous run Dashed lines on the move profile show how moves 1 and 2 would blend if move 1 were continu ous run The axis decelerates at the programmed rate for move 2 It reaches zero velocity at the pro grammed endpoint for move 2 then stops and waits Execution of the next move begins only after a motion command is received in the motion control block The halt command has priority over both the single step and run commands Consequently the axis stops at the programmed endpoint and waits for a go command Single step or continuous commands have no effect when the halt command is programmed Continuous The axis moves at the programmed final rate to the programmed endpoint then immediately begins executing move 4 by accelerating to the move 9 final rate Run 2 Compare move 2 single step run and move 2 continuous halt and move 4 Continuous 1 axis decelerates from the programmed final rate for 4 1 0 Run move 4 so it reaches the final rate for move 5 at
26. Disable Power Supply at bto 30V dc 10 Drive Disable Input on Customer s Servo Drive b Current Sinking Configuration Drive Enable Q1 on Current is sunk thru terminal 9 and Q1 8 2k Drive Disabled Q1 off Current thru Q1 is inhibited Terminal 9 is pulled up to the 4 potential of terminal 8 e 9 Customer s Drive Disable Power Supply e Qi Drive Disable 5109040 P Input on Customer s Servo Drive 10 12023 For the drive disable circuit you must provide a 5 30V dc power supply which can provide 100mA maximum The power supply can be separate or an integral part of the servo drive Each of the configurations of figure 6 13 includes a separate power supply 1 Chapter 6 Installing the Assembly Figure 6 13a shows a current sourcing configuration Normally the drive disable circuit is on sourcing current into the drive thru terminal 10 When the drive disable circuit turns off the drive is disabled Figure 6 13b shows a current sinking configuration Normally the drive disable circuit is on sinking current from the drive thru terminal 9 When the drive disable circuit turns off the drive is disabled Figure 6 14 shows how to connect the drive disable circuit to the Bulletin 1388 servo drive which has an internal power supply and requires a current source to enable it Figure 6 14 Connection Details for Providing a Drive disable Signal to the Bulletin 1388 Servo Driv
27. 1 0 0 Identifies this as No of Axes a parameter block 0 0 1 1 0 1 1 2 0 Inch 1 1 1 3 1 Metric 11031 Address Pointers Words 2 through 5 specify the starting addresses of the parameter command and first moveset block for each axis Figure 7 10 7 19 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 10 Address Pointer Words Word 2 Word 3 Word 4 Word 5 Word 6 7 20 Parameter Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Data table address of parameter block BCD format Command Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 FO J Data table address of command block BCD format Axis 1 Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 FO aa i Data table address of first moveset block to be transferred for axis 1 BCD format Axis 2 Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Data table address of first moveset block to be transferred for axis 2 BCD format Axis 3 Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
28. 11 Position Preset MS Word Axis 3 4 Control Word 2 Axis 2 12 Position Preset LS Word Axis 3 5 Position Preset MS Word Axis 1 6 Position Preset LS Word Axis 1 7 Position Preset MS Word Axis 2 8 Position Preset LS Word Axis 2 11815 7 60 Chapter 7 Formatting and Interpreting Data Blocks Axis Control Word 1 The functions of many of the bits in axis control word 1 depend on the state of bit 7 which determines whether the mode of operation is auto or manual Figure 7 41 Figure 7 41 Axis Control Word 1 Axis Control Word 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 1111010 A Auto Manual Control Word 11D NT Move doge Auto Manual Start Jog Initialize Begin Home g Preset EOM Search Moveset New Override Parameter Stop Home Offset Escape Go Home Slide Reset Stop Software Stop 1 Auto Mode 0 Manual Mode 11025 Bit 0 Next Move In the auto mode turn on bit to generate a next move command The next move command causes the servo positioning assembly to discontinue executing the current move and start executing the next move If the endpoints for the current move and the next move are in the same direction from the
29. 8 18 Chapter 8 Figure 8 9 Block transfer Time Computation Step 4 Compute the 1771 M3 controller read write block transfer time Example values have been added Program Scan Time program 2 5ms per 1K words x 20K words 25x20 50ms Scanner Time Time read or write 512ms for channel 1 and 77ms for channel 3 from results of sep 3 Read Write Time Program scan 2 Scanner Timer 1771 M3 Controller 50 2 512 in Channel 1 50 1024 1074ms 1 1 seconds Time Program scan 2 Scanner Time 1771 M3 Controller 50 2 77 in Channel 3 204ms Reducing Scan Time Due to the asychronous scan relationship between program scan and I O scan and the serial operation of each channel in the scanner we suggest that you optimize the overall scan time Although recommendations are application dependent we make the following recommendations as general guidelines Whenever possible control the manner in which block transfer instructions are enabled For example if only a few block transfer modules require frequent transfer of data as the 1771 M3 controller program them to run continually Inhibit block transfer instructions of those modules that require less frequent transfer until enabled by a timer and or some application dependent condition Distribute your block transfer modules equally between all four scanner channels Distribute block transfer instructions equally throughout your program
30. Auto Mode Issue GO command to execute profile Check status block NO to find move that caused execution to stop Profile executed o k END 11068 OS 10 10 Chapter 10 Troubleshooting Flowchart Notes The following notes are referenced by numbers of the flowchart of Figure 10 5 1 Refer to section titled Monitoring 1771 M3 Controller Indicators in this chapter 2 CAUTION To guard against damage to equipment power down the system before removing or installing any module 3 Refer to Figure 6 1 4 Refer to section titled Monitoring 1771 ES Expander Indicators in this chapter 5 On the left 1771 ES expander wiring arm measure the voltage at terminal 1 with respect to terminal 12 It should equal the input supply voltage If it doesn t check the power supply If it does measure the voltage at terminal 11 This voltage should be zero If it s not zero check for a closed circuit between terminals 11 and 12 Refer to Figure 5 1 and section titled Discrete Inputs 6 The module address programmed in the block transfer instruction must be the address of the 1771 M3 controller The rack number in the module address must match the setting of the I O chassis switches 7 Refer to the sample program of section titled Programming Example in chapter 8 for examples of rungs that perform this function 8 The second word o
31. Bit 16 Tachometer Calibrate Turn on bit 16 for the tachometer calibration procedure described in chapter 9 At all other times leave it off Chapter 7 Formatting and Interpreting Data Blocks 7 76 During tach calibration bit 15 of the most significant home position word in the parameter block loss of feedback detection enable must also be on This bit is ignored when the servo positioning assembly is in auto mode Bit 17 Get New Preset Value When you turn on bit 17 the 1771 M3 controller requests a command block transfer to include the position preset for the axis The servo positioning assembly uses the position preset value when you issue a preset command for the axis The command taken bit of the status block is on as long as the get new preset value bit is on unless the preset data results in a programming error When bit 17 is off the position preset words are not transferred to the 1771 M3 controller during command block transfer Note that the preset command causes the 1771 M3 controller to use the position preset value that was transferred to the 1771 M3 controller during execution of the most recently issued get new preset value command Position Preset Words Two words of the command block are used to specify a new position preset value for the axis Figure 7 45 These two words are requested by the 1771 M3 controller when the get new preset value bit is on Note that bit 17 of the most significant
32. EOM stop command When this bit is on the servo positioning assembly completes the current move by decelerating to zero velocity and stopping at the programmed endpoint for the move If the EOM stop command is received when the axis is beyond the point where it can stop at the programmed endpoint after decelerating the servo positioning assembly decelerates axis motion to zero velocity then moves the axis in the opposite direction to the programmed endpoint When axis motion has stopped the in position done and ready bits in the status block are on You can continue moveset execution after an EOM stop with a start command When you issue the start command the axis attempts to move to the endpoint of the move following the EOM stop move However a begin command causes the axis to execute the first move block in the current moveset block In a typical use of EOM stop an operator commands an EOM stop switches to manual mode then jogs the axis to a convenient location for an operation such as a tool change Before restarting moveset execution the operator typically issues a return to position command which causes the axis to move to the endpoint of the last executed move at the selected jog rate If you issue no return to position command before the start command the axis attempts to accelerate to the final feedrate of the next move in the moveset and continues moveset execution Figure 7 43 shows three examples of what can happen in thi
33. Place an equal number of non block transfer rungs between block transfer rungs Consider the last rung adjacent to the first For large numbers of block transfer instructions distribute groups of block transfer rungs equally throughout your program Place no more than four block transfer rungs consecutively in one group one block transfer instruction per rung Within each group condition the next rung using the done bit of the previous block transfer instruction 8 19 Chapter 8 8 20 Consider an additional I O Scanner Module cat no 1775 S4A SAB if you cannot otherwise reduce the block transfer times to meet your timing requirements During a write handshake the processor also can transfer write data and during a read handshake the processor also can transfer read data Special Considerations When using one 1775 S4A I O scanner with thumbwheel switchset to 1 only part of its data handling capacity is available for block transfers This scanner can store and transfer a maximum of 72 words at any one time from up to four block transfer modules across any of the active channels If a block transfer read instruction is enabled but the scanner s buffer cannot accept the instruction s block length the scanner is processing other blocks of data the block transfer instruction must wait for a subsequent scan when the scanner s buffer can accept all the words that the module has to transfer The same applies for
34. and 15 as 1111 1001 0111 0010 convert it to hexadecimal as F972 8 32 451 0043 Program Rungs for PLC 2 30 Chapter 8 Figure 8 16 shows the ladder diagram programming for this application for a PLC 2 30 system Rungs 1 thru 4 of the program implement bidirectional block transfer The remaining rungs are for data input and display Here are individual rung descriptions Figure 8 16 PLC 2 30 Ladder diagram Programming Example for Controlling 2 Axes 0141 8 PUT 3 02 200 400 455 02 451 455 0450 0141 LIA E G 02 02 400 400 030 BLOCK XFER READ EN J DATA ADDR 0040 B 17 MODULE ADDR 301 430 BLOCK LENGTH 00 DN FILE 0447 0546 B 17 030 BLOCK XFERWRITE EN DATA ADDR 0041 16 MODULE ADDR 301 439 BLOCK LENGTH 00 FILE 0400 0477 n 041 Axis 1 Status 0044 t FILE TO FILE MOVE EN 15 COUNTERADDR 0044 17 POSITION 001 FILE LENGTH 02 0044 FILE A 0451 0452 FILE B 0020 0021 15 RATE PER SCAN 002 Axis 2 Status FILE TO FILE MOVE 0047 t COUNTERADDR 0047 EN 15 POSITION 001 17 FILE LENGTH 02 FILE A 0455 0456 0047 FILE B 0022 0023 py RATE PER SCAN 002 15 Rung 1 Rung 2 Rung 3 Rung 4 Rung 5 Rung 6 8 33 Chapter 8 8 34 110 110 Jog Next Move an F m 00 0
35. for the current move when the servo positioning assembly is in auto mode After completion of a slide stop status block bits for slide stop done in position and ready turn on If you issue the slide stop command while the servo positioning assembly is in manual mode and the axis is in motion the axis stops at the global decel rate programmed in the parameter block Bit 6 Software Stop Turn on bit 6 to generate a software stop command This command causes the servo positioning assembly to go into the immediate stop condition In this condition it immediately clamps the analog output voltage to zero and turns off the drive disable circuit to disable the servo drive The servo positioning assembly executes the software stop command in both auto and manual modes The servo positioning assembly goes into the immediate stop condition in response to loss of power software stop command from command block hardware stop input open excess following error timeout of a firmware or hardware watchdog loss of feedback To recover from an immediate stop condition you must either issue the reset command or cycle I O chassis power Note that the 1771 ES expander continues to monitor current axis position 7 69 Chapter 7 Formatting and Interpreting Data Blocks 7 70 Bit 7 Auto Manual Bit 7 selects the mode of operation of the servo positioning assembly On Auto Mode In auto mode the servo positioning assembl
36. 07 06 05 04 03 02 01 00 metric seconds Least significant digits 6 2 Multiplier 001 x 10 000 x 10 010 x 10 100 x 10 110 x 10 111 2 x 10 Chapter 6 Moveset Block Local Feedrate Word Do not include this word if you select global feedrate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 i inch metric This BCD value 0 999 ipm or 19 99 mmpm max times the multiplier is the local feedrate Local Accel Word Do not include this word if you select global feedrate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 EN metric inch Acceleration rate ipm sec or mpm sec meters min sec BCD format Local Decel Word Do not include this word if you select global feedrate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 N metric inch Deceleration rate ipm sec or mpm sec meters min sec BCD format Next Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Data table address of next moveset block BCD format 6 3 Command Block Single Axis c Three Axis Word Word 1 Control Word 1 1 Control
37. 1326 dc servo Motors to match the Bulletin 1388 dc Servo Controllers 5 3 Chapter 5 Hardware Description 5 4 Tachometer Input Terminals 11 and 12 on the right wiring arm provide connection points for the velocity feedback signal from the tachometer Although the velocity loop is closed on the servo drive the 1771 ES expander uses the velocity feedback signal to compare to the position feedback signal from the encoder If the module detects an imbalance between these signals it disables the servo drive and sends a loss of feedback signal through the status block The 1771 ES expander accepts a full scale tachometer signal of 3V to 50V dc If the full scale tachometer signal is greater than 50V dc you must reduce it through a voltage divider on the servo drive before connecting it to the module CAUTION Do not connect a signal greater than 50V dc across these terminals A signal greater than 50V dc could damage the 1771 ES expander Hardware Done Output Terminal 7 on the right wiring arm provides a connection point for a hardware done output signal Figure 5 3 Chapter 5 Hardware Description Figure 5 3 Schematic Diagram of the Hardware done Output Cirucit 1771 ES Expander 3 ANALOG SUPPLY 15Vde e NOT USED ANALOG OUTPUT ANALOG RETURN 15Vde COMMON ANALOG SUPPLY 15Vdc NOD oO
38. 2 4 4 Keying uid Bands EN 2 8 10 10 12 12 C 514 14 16 16 Between 18 18 Between pins 2 and 4 20 20 pins 4 and 6 e pins 14 and 16 22 e pins 32 and 34 24 24 26 26 28 28 30 30 32 32 34 34 i 2 11006 To insert a module into an I O chassis follow these steps 1 Remove power from the I O chassis before inserting or removing module Open the module locking latch on the I O chassis and insert the module into the slot keyed for it Press the module firmly to seat it into its backplane connector Secure the module in place with the module locking latch if you cannot seat a module with firm pressure check the alignment and keying Forcing a module can damage the backplane connector or the module A CAUTION Do not force a module into a backplane connector 6 9 Chapter 6 Installing the Assembly Connecting to Terminals Make connections to the 1771 ES expander as shown in Figure 6 7 Figure 6 7 Simplified 1 0 Terminal Connection Diagram Input Power we eel l 50
39. 2 Move 3 Normal Positioning Position with Offset Normal Positioning Offset value E TK NN 4 SON 4 NN N D ist Offset mum f Position N e M 2nd Offset NON J Move 4 Normal Positioning 11018 Changing the offset value in the parameter block has no effect on the two move blocks already stored on board the 1771 ES expander module but only on subsequent move blocks Bits 11 10 06 Set to 100 Preset to Position Turn bit 11 on bit 10 off and bit 06 off to generate a preset to position This command clears the accumulator register to zero and sets the position register to the value specified in the position words Instead of generating axis motion this command redefines the present axis position Bits 11 10 06 Set to 110 Dwell Turn bit 11 on bit 10 on and bit 06 off to generate a dwell This command inhibits the 1771 ES expander from executing the move block 7 49 Chapter 7 Formatting and Interpreting Data Blocks 7 50 that follows for the amount of time specified by the value in the position or dwell words Bits 12 and 13 SMCW ID Bits 12 and 13 must be on to identify the word as an SMCW If they are not on the status block indicates programming error 20 Bit 14 Accel Decel If you turn on bit 14 you must include local acceleration and deceleration rate words in this move block Note that if you select local accel decel you enter separate acceleration and decelerat
40. 44 63 for its loss of feedback detection feature Figure 7 28 The tachometer calibration procedure explains how to select the value for this word Chapter 7 Formatting and Interpreting Data Blocks Figure 7 28 Following Error Reduction Tachometer Conversion Factor Word FE Reduction Tach Conversion Factor 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 25 Axis 1 n Word 44 Axis 2 Word 63 Axis 3 vV Pig e BCD following error reduction value 0 99 9 d 0 0 1 0 125 0 0 Total value is the sum of the 10250 selected values 0 0 1 0 500 Used if full scale analog output A voltage is greater than tachometer voltage for a given rpm Refer to the tachometer calibration procedure in chapter 9 11050 Each of bits 0 thru 3 corresponds to a factor The total factor used by loss of feedback detection equals the sum of the individual factors selected If you are not using the loss of feedback detection feature or if tachometer voltage is greater than or equal to 10V program zero for all bits of this word Following Error Reduction The servo positioning assembly accepts the BCD value you enter into bits 04 thru 17 as the following error reduction value Figure 7 28 You can command a reduction of the following error by 0 through 99 9 The 1771 ES expander reduces the following error through feed forwarding without increasing the positioning loop
41. 6 16 Tachometer input terminal 12 on the 1771 ES expander and terminal 2 on the drive each connect to a dc common at ground potential therefore you must connect these terminals directly as shown Connect the analog output signal from terminal 3 of the 1771 ES expander to terminal 7 of the drive Connect the analog return signal from terminal 4 of the 1771 ES expander to terminals 6 and 8 of the drive With this signal orientation when you connect the tachometer to the drive with the proper polarity for negative feedback the signal will also have 6 28 Chapter 6 Installing the Assembly the proper polarity for loss of feedback detection at the 1771 ES expander If you use the opposite analog output signal orientation you will not be able to utilize the loss of feedback detection feature WARNING Always utilize the loss of feedback feature Without loss of feedback detection if encoder or tachometer feedback is lost unexpected axis motion can occur resulting in damage to equipment and or injury to personnel Limit the cable lengths to 50 feet If your application requires a cable length greater than 50 feet contact your local Allen Bradley representative Grounding Cable Shields Figure 6 17 is a pictorial representation of the shielded cable connections Mount a ground bus directly below the I O chassis to provide a connection point for cable shield drain wires and the common connections for the input circuits Connect th
42. Chapter 10 Troubleshooting Command results in overflow of offset accumulator Attempted context switch with dual meaning bit on Manual mode only bit s on while in auto mode Invalid motion command bit combination or command not allowed Invalid command cannot process new parameters preset or offset commands while axis is in motion Attempted switch to auto mode before first marker is found Attempted context switch while axis is commanding motion n auro mode 32 Troubleshooting Flowchart The flowchart of Figure 10 5 provides a logical procedure to help isolate a problem with servo positioning assembly operation You can also use it at system start up to check out the servo positioning assembly for proper operation Many of the flowchart boxes that specify corrective actions contain more than one instruction When using the flowchart perform instruction 1 first If this fails to correct the problem perform instruction 2 and so on Your ladder diagram program should allow you to display parameter moveset command and status block on an industrial terminal Chapter 10 Troubleshooting References in reverse type are to the notes in section titled Figure 10 5 Troubleshooting Flowchart Consult Assembly and Installation PC Manual onitoring the Status Block 1 Data blocks overlap processor or program moman 2 Invalid block transfe starting addresses 3 Replace 1771 M3
43. Rung 4 writes the parameter command or moveset block to the 1771 M3 controller module as requested by the 1771 M3 controller via the status block The data address 0041 is in the timer counter accumulated area of the data table Module address 301 is explained in the rung 3 description The block length 00 is the default length This allows the 1771 M3 controller to control the number of words transferred according to the block it requests During a write operation data transfers from consecutive data table words starting with the first word of the parameter command or moveset block These blocks have starting addresses 0200 0400 and 0500 respectively Other moveset blocks start at addresses 0600 and 0700 Rung 5 Rung 5 transfers the third and fourth words of the status block to digital outputs in module groups 0 and 1 of rack 2 We use these outputs to display the position following error and diagnostic codes for axis 1 Rung 6 Rung 6 transfers the seventh and eighth words of the status block to Chapter 8 digital outputs in module groups 2 and 3 of rack 2 We use these outputs to display the position following error and diagnostic codes for axis 2 Rungs 7 thru 60 Rungs 7 thru 60 use discrete inputs to individually control bits of control words and 2 for each axis in the command block You would not need a rung to control bit 16 tachometer calibrate of axis control word 2 because you only need to turn on thi
44. To connect the analog output supply follow these steps 1 Connect the plus side of the analog and hardware one output power supply to terminal 1 of the right wiring arm 2 Connect the minus side to terminal 6 6 21 Chapter 6 Installing the Assembly 6 22 3 Connect the common to terminal 5 4 Connect the shield to ground at the I O chassis Connecting Velocity Command Connect the analog velocity command output signal from terminals 3 and 4 on the right wiring arm to the corresponding terminals of the servo drive Reversing these connections reverses the direction the axis moves in response to the velocity command Connect this signal so that the direction of motion that results from it matches the correct direction of motion as you have defined it Connect the shield to ground at the servo drive end Chapter 6 Installing the Assembly Connecting Hardware Done Figure 6 12 shows details of how to connect hardware done Follow these steps Figure 6 12 Connection Details for Hardware Done Output 15V dc For DAC customer supplied Comm Right Wiring Arm of 1771 ES Expander 15V 15V Wiring Arm of 1771 Input Module Belden 8761 or equivalent 50ft max Hardware Done aaa a BEA M 1 ue ae 29 Au Cc ESA
45. Word 25 Axis 1 Lee omer fi T 5 BCD following error reduction value 0 99 996 0 0625 928125 08250 9 8500 A Total value is the sum of the selected values Used if full scale analog output voltage is greater than tachometer voltage for a given rpm Refer to the tachometer calibration procedure in chapter 9 C 6 11050 Appendix C Parameter Block Parameter Block Values Parameter Limits is Maximum D A Voltage 0 01 10 00V Backlash Takeup 0 7999 0 7999 in 7 999 7 999mm Offset 0 7999 0 7999 7 999 7 999 Following Error Reduction 0 99 9 External Synchronization of Feedrate Override Enable Disable Loss Of Feedback Detection Enable Disable Tachometer Conversion Factor 0 1111 binary C 7 Moveset Block Moveset Control Word MCW Single Move Control Word SMCW Position or Dwell Time MS Position or Dwell Time LS jit Local Acceleration Local Deceleration Single Move Control Word SMCW Up to 64 words P OT Move Block 2 Position or Dwell Time MS 8 words Position or Dwell Time LS Single Move Control Word SMCW Position or Dwell Time MS Move Block N 1 Position or Dwell Time LS 4 words Local Feedrate Single Move Control Word SMCW Position or Dwell Time MS Position or Dwell Time LS Move Block N Local Feedrate 6 words Local Acceleration Local Deceleration
46. a write block transfer instruction Block Transfer Errors Once enabled a block transfer instruction will set either a done bit or an error bit The instruction indicates an error when it illuminates the ER symbol Typical block transfer errors occur when You do not correctly enter the instruction rack group and module numbers do not match the location of the installed module you entered a file length greater than 64 words you did not create the data file or the address that you entered does not match the file you created If the read and write error bits are on at the same time the error source is the module address entry or the file length entry in the instruction block You have a communication problem you did not correctly connect the twinaxial cable to the scanner you did not connect a terminator resistor to each end of the twinaxial cable When the scanner encounters a communication fault it tries twice to complete the transfer it sets the error bit after the second unsuccessful try Programming Example Chapter 8 When the scanner and or processor detects a block transfer error it halts the transfer Transfers from that module are prevented until your program clears the instruction s control word clears the error Figure 8 10 you locate and correct the error Figure 8 10 Example Rung to Clear the Control Word CTRL WORD MOV Mi MOVE FROMA TO R 03 A STORAGE WORD 000
47. all axes are in position you can send a start command to each axis through the command block Alternatively you can monitor the in position signal of each axis through the hardware done output terminal of the 1771 ES expander When all axes are in position you can send a start command to each axis through the hardware start input terminal of the 1771 ES expander Using the hardware start and done signals is faster than using block transfer for the status and command blocks Furthermore if the axis synchronization includes multiple servo positioning assemblies precise synchronization cannot occur through block transfer because two block transfers cannot occur simultaneously Continuous Moves For continuous moves with the next move in the same direction axis synchronization requires precise programming of feedrates acceleration rates and deceleration rates You must program the move blocks so that each axis takes the same amount of time for corresponding moves Furthermore you must plan the moves to be long enough to adhere to the following constraints Each move must take longer than the time it takes to transfer a move block from the 1771 M3 controller to the 1771 ES expander This time is a function of the number of axes as follows No of Axes Time 1 20ms 2 25ms 3 30ms fthe number of moves requires additional moveset blocks the last two moves of each preceding moveset block must not be too short They must take a long
48. an emergency To stop an axis in a non emergency situation use the slide stop bit in the command block thru the ladder diagram program A slide stop decelerates the axis feedrate before stopping it After a slide stop you can use an emergency stop switch if you want to remove power Connect a set of normally open CRM contacts in series with servo transformer overload servo drive fault and servo motor overload contacts Connect this series of contacts between the hardware stop input terminal and common The opening of any of these contacts indicates that power to the servo motor is interrupted When any of these sets of contacts open the hardware stop circuit the following occur 1 When this circuit opens the 1771 ES expander immediately sets the velocity command output to zero and disables the serve drive by turning off the drive disable circuit Chapter 6 Installing the Assembly 6 16 2 The 1771 M3 controller sends the hardware stop signal to the PC data table thru the status block transfer 3 After this circuit closes again the 1771 ES expander still holds the velocity command at zero and holds the servo drive disabled until you either senda reset signal through a command block transfer This allows the 1771 ES controller to maintain the accumulated axis position cycle I O chassis backplane power off then back on This clears the accumulated axis position When you restart the axis after a hardware stop the a
49. axis motion according to your requirements The servo positioning assembly cannot overcome inherent limitations of drives motors or axis mechanisms We present axis integration procedures in the order in which you must perform them Open Loop Procedure You disconnect the 1771 ES expander from the servo drive to open the positioning loop and use a battery box to supply drive input You check phasing of drive input and axis feedback You check axis motion for smoothness and response Closed Loop Procedure You close the axis positioning loop and check axis response to commands from the 1771 ES expander Tachometer Calibration You must perform this procedure to ensure proper functioning of the loss of feedback detection feature The following procedure requires a battery box to supply command voltage to the axis drive If a commercial battery box is not available you can make one according to the circuit of Figure 9 1 A 9 volt battery a 10 ohm variable resistor and a 2 pole 3 position switch are required You can use a dpdt toggle switch with a center off position You can connect a voltmeter across the battery box output as shown to measure output voltage Figure 9 1 Diagram of Battery Box 9 1 Chapter 9 Integrating Axes 9 2 9 Volts BEN 10K O Command 0 e Return 11064 The following steps form the open loop axis integration procedure
50. chassis add up it current load on the backplane power supply Be sure that this total current is not so large as to overload the backplane power supply The backplane power supply current load of the servo positioning assembly is 1771 M3 controller 1771 ES Total expanders Current Note that if you add the total current draw of one 1771 M3 controller three 1771 ES expanders and either an I O adapter or mini processor module the total would exceed 8A In that case you could not use a 1771 P1 or 1771 P2 power supply because they are rated at 6 5A If the total current exceeds 6 5A you can use Power Supply Modules cat no 1771 P3 P4 P5 to provide 8A 11A or 16A The following table lists the number of axes you can control with a servo positioning system in a 1771 A4 I O chassis based on power requirements and compatibility of other components used with the 1771 A4 I O chassis 1 0 Adapter or Mini Processor Module Cat No 1771 AL 1771 AS 1772 05 1772 LSP 1771 LV 1771 P3 1771 P4 plus 1771 P3 or a second 1771 P4 3 Axes 3 Axes Setting Switches and Jumpers Chapter 6 Installing the Assembly Planning Module Location The 1771 M3 controller requires one I O chassis slot You can install it in any I O in the I O chassis The 1771 M3 controller uses both the output image table byte and the input image table byte that correspond to its location address The 1771 ES expander requires two s
51. controller YES 1 Check I O chassis power supply 2 Power down reseat 1771 M3 controller 3 Replace 1771 M3 B controller 10 8 1 Switch settings 2 Power down reseat 1771 ES expander 3 Replace 1771 ES B expander OFF ON START Processor RUN indicator ON yo adapter ACTIVE Indicator PC communications fault indicator Expander communication 1771 M3 controller EN ACTIVE indicator on constan 1771 ES expander a ACTIVE indicator on 1771 ES Expander iagnostic indicato on Consult PC installation manual fault indicator a 1 1771 ES expander switch settings 2 Replace 1771 M3 controller 3 Replace 1771 ES py expander s 1 Power down reseat 1771 ES expander 2 Cycle power at I O chassis 3 Replace 1771 ES expander 1 Cycle power at I O chassis 2 Replace 1771 ES expander 3 Replace 1771 M3 controller B 11068 OS Chapter 10 Troubleshooting Figure 10 5 Troubleshooting Flowchart continued 1 Reset 1771 ES expander wiring arms 2 Check hardware stop circuit 3 Issue Reset command via command block 4 Cycle power at I O chassis Check parameter block address pointer words 2 through 5 1 Check for active stog commands 2 Re check for errors in status block 3 Cycle 1771 ES
52. current axis position the axis accelerates or decelerates to the final velocity for the next move at the programmed acceleration rate for the next move If the endpoint for the next move is in the opposite direction from the endpoint of the current move the servo positioning assembly performs a slide stop using the decel rate programmed for the current move then executes the next move bit 5 slide stop 7 61 Chapter 7 Formatting and Interpreting Data Blocks If you issue a slide stop command before the next move command so that the axis is stopped when you issue the next move command the servo positioning assembly starts execution of the next move without completing execution of the current move If you issue the next move command at a time when the axis cannot decelerate at the programmed rate without passing the endpoint of the next move the servo positioning assembly executes a slide stop that carries the axis past the next move endpoint then moves the axis in the opposite direction to the desired endpoint If no data for a next move is available when you issue a next move command the 1771 M3 controller sets the insufficient data bit in the status block and performs a slide stop if the axis is in motion Figure 7 42 Moveset Profile Showing Next Move Command Next Move Rate Command Next Move Command A AS s Position 0 Programmed Note All moves absolute 48 Executio
53. enough time for the following moveset block to be transferred from the data table Refer to chapter 8 for details about block transfer timing 4 9 4 Positioning with Allen Bradley PC Specifying Axis Position 4 10 Run Single Step Moves For run single step moves axis synchronization is dependent upon the axis response on each move The same is true for continuous moves with the next move in the opposite direction In both cases the 1771 ES expander executes the next move automatically as soon as the current move is done without waiting for a start signal However the time it takes for each move cannot be precisely calculated because the following error has to close before the move is done Auto Position Correction The auto position correction feature may prevent an accumulation of position error caused by occasional noise on the channel A and B inputs However if the environment is excessively noisy or if the cabling and shielding is not proper this feature causes the axis to jump or jerk This jump or jerk should indicate to you that a problem exists You enter the number of lines on the encoder and the feedback multiplier into the parameter block From this the 1771 ES expander knows how many feedback pulses it should receive each encoder revolution The module also receives a marker pulse each revolution Each time the 1771 ES expander receives a marker pulse it checks the value in the position
54. gain Consider an example in which you have entered an initial gain value of 1 00 With an axis speed of 10 ipm without following error reduction the following error would be 10 mils 7 39 Chapter 7 Formatting and Interpreting Data Blocks Moveset Block 7 40 FE speed lOipm 10mils gain 1 ipm mil However if you enter a following error reduction value of 70 0 the following error at 10 imp is reduced from 10 mils to 3 mils A moveset block contains a number of move blocks through which it describes axis motion for a sequence of moves Figure 7 29 Figure 7 29 Moveset Block Showing Word Assignments Moveset Control Word MCW Single Move Control Word SMCW Position or Dwell Time MS Position or Dwell Time LS sae 1 Local Acceleration Local Deceleration Single Move Control Word SMCW E Up to 64 words TTT TT OT Move Block 2 Position or Dwell Time MS 3 words Position or Dwell Time LS V Single Move Control Word SMCW Position or Dwell Time MS Move Block N 1 Position or Dwell Time LS 4 words Local Feedrate Single Move Control Word SMCW Position or Dwell Time MS Position or Dwell Time LS Move Block N Local Feedrate 6 words Local Acceleration Local Deceleration E Next Moveset Pointer If Required 11216 Each move requires a move block of at least three words a single move control word and two words to define position or dwell tim
55. in BCD format The maximum programmable value is 999 9999 inches If bit 14 of the most significant position word is on when the SMCW is programmed for inch units the status block indicates a programming error to inform the operator that a position value greater than 999 9999 inches has been programmed For metric values these words express an 8 digit number in BCD format The maximum programmable value is 19999 999 mm For position values use bit 15 of the most significant position word to specify the positioning mode Absolute If you turn off this bit the position value is an axis position coordinate relative to the zero position of the axis For example if the axis is at position coordinate 4 5 and the position words call for motion to absolute endpoint 3 5 the servo positioning assembly 7 56 Chapter 7 Formatting and Interpreting Data Blocks moves the axis one unit in the negative direction to position coordinate 33 5 Incremental If you turn on this bit the position word specifies the move endpoint relative to the most recently achieved programmed endpoint For example if the axis is at position 4 5 and the position word value is 43 5 the axis moves 3 5 units in the positive direction to position 8 0 Local Feedrate Word If you turn on the local feedrate bit in the SMCW you must include a local feedrate word after the position words Acceptable values depend on units Figure 7 37 Inch 0 0001
56. in the reverse direction can occur Note that the value you enter for the in position band is actually half the desired in position band value For example if the in position band value you enter is 5 then the servo positioning assembly considers the axis in position if it is within 10 increments of feedback resolution of the programmed endpoint Figure 7 18 illustrates the concept of in position band Figure 7 18 In position Band Example Programmed Endpoint N Position In Position Axis is considered In Position Band value stored in the when it is within 10 increments parameter block is 5 of the programmed endpoint 11040 Rapid Traverse Rate The rapid traverse rate you enter Figure 7 19 is the highest feedrate the axis can attain It is associated with open travel of the axis The servo positioning assembly uses this rate for the go home operation and for moves that you program to use the global feedrate Chapter 7 Formatting and Interpreting Data Blocks Figure 7 19 Rapid Traverse Rate Word Rapid Traverse Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 12 Axis 1 Word 31 Axis 2 j Word 50 Axis 3 inch decimal metric decimal Multiplier point 001 x 10 This BCD value 0 999 ipm or 000 x 10 19 99 mmpm max times the 010 x10 multiplier is the rapid traverse rate 100 2 x 10 non 110 x 10 111 2x10 The r
57. instruction The data blocks are status block parameter block moveset block command block The block transfer read instruction transfers status block data from the 1771 M3 controller to the data table The block transfer write instruction transfers the parameter block the moveset block and the command block data from the data table to the module Figure 7 1 7 1 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 1 The Status Block Transfers to the Data Table the Parameter Moveset and Command Blocks go to the 1771 M3 Controller Data Table 1771 M3 Controller Status Block Transfer Read Status Block Block Parameter Parameter Block Block Block Transfer Write Moveset gt Moveset Block Block Command Command Block gt Block 12029 Status Block The status block is regularly transferred to the data table to provide updated information about the current status of each axis This status includes actual axis position jn position at home position slide stop emergency stop software travel limit exceeded feed reduction excess following error auto manual mode address pointer to tell the program which block parameter moveset or control to write transfer to the 1771 M3 controller next diagnostic status that tells you where programming errors are in parameter moveset
58. mmpm max times the 100 x 10 multiplier is the low jog rate It must um 1 4 be lower than the high jog rate Excess Following Error MSD D A Voltage 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 15 Axis 1 Word 34 Axis 2 Word 53 Axis 3 V Most sianificant Maximum D A voltage ia ey analog output voltage E ra dus BCD format For 10 0V following error percentage BCD program 000 format Excess Following Error LSD D A Voltage 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 16 Axis 1 gt Word 35 Axis 2 Word 54 Axis 3 V V Least sionifi t Maximum D A voltage vds nha c analog output voltage CUR S BCD format For 10 0V following error percentage BCD program 000 format Excess following error percent should be greater than or equal to 6 The value entered here is the percent above rapid traverse following error at which Emergency Stop is to occur C4 Appendix C Parameter Block Most Significant Home Position 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 17 Axis 1 Word 36 Axis 2 X Wo
59. mmpm max times the 100 x 10 multiplier is the high jog rate It must 110 x 10 not be higher than the rapid traverse 1112 x10 rate Low Jog Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 14 Axis 1 Word 33 Axis 2 Word 52 Axis 3 Y inch metric Multipli i decimal ultiplier point 001 2 x10 000 x 10 This BCD value 0 999 ipm or 010 x 10 19 99 max times the 100 x 10 multiplier is the low jog rate It must i i 4 be lower than the high jog rate 11042 Chapter 7 Formatting and Interpreting Data Blocks Excess Following Error The excess following error parameter is a 2 digit BCD number that the 1771 ES expander interprets as a percentage above the following error allowed at the rapid traverse rate Programmable excess following error values can thus range from 0 through 99 Program the most significant digit in bits 14 through 17 of the first word and the least significant digits in bits 14 through 17 of the second word Figure 7 21 This parameter specifies maximum allowable axis following error When the following error reaches the maximum value permitted as specified by the excess following error parameter the servo positioning assembly stops axis motion by commanding immediate stop Figure 7 16 Figure 7 21 Excess Following Error D A Voltage Words Excess Following Error MSD D A Voltage 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 15 Ax
60. motion the servo positioning assembly smoothly accelerates or decelerates the axis to the escape move velocity then continues escape move execution If the escape move endpoint and current axis motion are in opposite direction the servo positioning assembly commands a slide stop After axis motion stops the escape move executes If no escape moveset is stored on the 1771 ES expander and the axis is not in motion when you issue the escape command the servo positioning assembly turns on the insufficient data bit in the status block and requests a new moveset block If the axis is in motion the servo positioning assembly performs a slide stop before turning on the insufficient data bit and requesting a new moveset block You can issue a start begin or next move command to start execution of the new moveset Bit 4 Go Home In the manual mode turn on bit 4 to generate a go home command When this bit is on this command causes the axis to move to the home position at rapid traverse rate using the accel decel rate you specify in the parameter block Chapter 7 Formatting and Interpreting Data Blocks If you issue the go home command before execution of any search home or initialize home command the axis moves to an erroneous home position Bit 5 Slide Stop In either mode turn on bit 5 to generate a slide stop command This command causes the axis to decelerate to a stop at the programmed deceleration rate local or global
61. must re establish the home position after each time power to the I O chassis backplane goes off because the encoder feedback is incremental Connecting Jog Reverse Feedrate Override Enable Figure 6 9 shows details of how to connect jog reverse and feedrate override enable Follow these steps 1 Provide a 3 pole selector switch to select between auto and manual mode 2 Connect one pole of the selector switch to a discrete input module terminal Use this input to control the auto manual bit in the control block This bit controls whether the 1771 ES expander is in the auto or manual mode 3 Connect a second pole of the selector switch to the jog reverse feedrate override enable terminal of the 1771 ES expander 4 Connect a momentary contact jog reverse switch to the selector switch contact corresponding to manual on the second pole 5 Connect a momentary contact feedrate override switch to the selector switch contact corresponding to auto on the second pole Chapter 6 Installing the Assembly Figure 6 9 Connection Details for Jog Forward Hardware Start and Jog Reverse Feedrate Override Enable 3 Pole Selector Auto Switch Bu Discrete input module N terminal to control Manual the auto manual bit in the command block 5 to 30V dc Input Power To other axes Supply A customer supplied ic PK quum Hardware Start Jog MESE Forward ii n l O Manual Fe
62. off remove the potentiometer from between the tachometer signal and the 1771 ES expander Measure the resistance the potentiometer was providing Replace the potentiometer with a fixed resistor of equivalent value to limit the tachometer signal into the 1771 ES expander to 50V 9 9 Chapter 9 Integrating Axes 9 10 7 Restore power and jog the axis in either direction While the axis is moving measure the voltages at the white and yellow test points on the 1771 ES expander DAC and tachometer voltages respectively with respect to terminal 4 analog return on the right wiring arm of the 1771 ES expander Figure 9 4 These voltages should have the same polarity when jogging in the positive direction while jogging in the negative direction Figure 9 4 Tachometer Calibration Procedure Voltage Reading 11 o sss White Voltmeter Yellow V Analog Return 1771 ES Expander 11067 While jogging the axis adjust the tach course potentiometer counterclockwise until the tach cal indicator just changes state Then jog the axis in the other direction and turn the tach course potentiometer clockwise until the tach cal indicator begins to flicker Turn off the tachometer calibrate bit in the command block Summary Chapter 9 Integrating Axes WARNING To guard against possible injury or damage to equipment before proceding with step 10 keep all pers
63. one 1771 M3 controller Channel 4 is made inactive thru LIST You can compute the read write block transfer times for the 1771 M3 controllers in this example in four steps An accompanying figure explains each of the following four steps 1 Diagram the I O channels of your PC system Figure 8 6 showing the number of 8 16 Chapter 8 block transfer modules in each I O chassis block transfer I O channels I O chassis entries in the chassis scanning sequence list for each block transfer I O channel active I O channels per scanner Figure 8 6 Diagram of PLC 3 I O Channels Step 1 Diagram the chassis connected in series to each channel up to 4 of your scanner module Then fill in the information called for below Example values have been added Scanner 1 1 1 2 1 2 O chassis 2 0 0 n number of block transfer modules 3 1 0 in chassis 4 Make inactive through processor LIST Description Number Ch 1 Ch2 Ch3 Ch4 Active I O channels 3 Block transfer I O channels 2 Block transfer modules on each I O 7 0 1 0 block transfer channel I O chassis on each block transfer I O 5 0 2 0 channel I O chassis in rack list A block transfer I O channel is a channel that contains one or more block transfer modules located in any chassis connect
64. oun decimal t oin 1 Loss of feedback Most significant digits i detection External 0 disable synchronization of 1 enable feedrate overide 0 disable BCD home position value 1 enable 999 9999 inches or 19999 99 mm max Home Position Least Significant Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 18 Axis 1 Word 37 Axis 2 Word 56 Axis 3 metric decimal Least significant digits point 11044 Loss of Feedback Detection Enable Turn bit 15 off until you complete the open loop and closed loop axis integration procedures chapter 9 Then turn on bit 15 of the most significant home position word to enable the loss of feedback detection feature of the 1771 ES expander WARNING Once you have completed the axis integration procedures never turn this bit off Without loss of feedback detection if encoder or tachometer feedback is lost unexpected axis motion can occur resulting in damage to equipment and or injury to personnel External Synchronization of Feedrate Override Turn on bit 16 of the most significant home position word to have the 1771 ES expander recognize the feedrate override enable input Figure 7 22 7 33 Chapter 7 Formatting and Interpreting Data Blocks With this bit off you change the feedrate by the percentage you enter in the command block when you enable feedrate override i
65. positioning loop It commands axis motion by generating an analog voltage for your servo drive Every 2 4 milliseconds ms it updates this analog output voltage according to motion commands from the 1771 M3 controller discrete inputs and 2 3 Chapter 2 Introducing the Servo Positioning Assemb Its Features 2 4 feedback from your encoder The 1771 ES expander is able to provide this fast servo sample rate because the update is independent of the I O scan A drive disable output provides a signal to disable the servo drive in conditions such as loss of feedback or a hardware stop signal A hardware done output signals the completion of each single step move Discrete hardware inputs include hardware stop jog forward jog reverse home limit feedrate enable hardware start The 1771 M3 controller sends axis status and diagnostic data to the data table as directed by a block transfer read instruction Because axis command and status data is stored in the data table axis motion control can interact with other axes discrete I O and report generation See the following table for a list of the many useful benefits you ss derive from an A B servo positioning assembly Feature incremental digital encoder feedback absolute or incremental positioning commands programmable gain break programmable acceleration deceleration programmable in position band programmable jog rates programmable dwel
66. positioning systems Therefore as you read this manual you should be aware of the names we use for these components We refer to the Servo Controller Module cat no 1771 M3 as the 1771 M3 controller We refer to the Servo Expander Module cat 1771 ES as the 1771 ES expander Werefer to the device that receives the velocity command signal from the 1771 ES expander as the servo drive The servo drive converts ac power to dc power for the servo motor in proportion to the velocity command signal What we refer to here as the servo drive others may refer to as a servo controller So if you refer to this device as a servo controller be aware of our nomenclature as you read this manual PCrefers to programmable controller For an extensive list of terms we use this publication refer to the glossary in appendix A 1 Troubleshooting Manual Organization This manual is organized into the following chapters Chapter Title What s Covered 2 Introducing the Servo overview of the servo positioning Positioning Assembly assembly its applications functions and features 3 Positioning Concepts concepts of closed loop positioning including velocity loop positioning loop and feed forward 4 Positioning with the servo positioning assembly s position in Allen Bradley PC s a servo system and the servo positioning assembly s communication with the PC processor 5 Describing Hardware describing the servo po
67. register to see if it is an even multiple of the number of feedback pulses per revolution If the value is off the 1771 ES expander will automatically adjust it This feature corrects position errors caused by noise on the channel A and B encoder feedback signals However the function of this feature assumes a noise free marker signal The marker signal does have some noise protection because the 1771 ES expander only accepts a marker signal when the channel A and B signals are high unless you set the marker logic jumper to the not gated position To command axis motion you must be able to specify axis position by establishing an axis position scale or coordinate system for each axis 4 Positioning with Allen Bradley Figure 4 9 shows an example of an axis and its position scale Any axis position within the range of travel can be identified by a number For the servo positioning assembly the axis position scale can be either in inches or millimeters The position scale is an internal scale used by the servo positioning assembly to identify axis position It is not printed on the axis slide You can shift the axis position scale by entering through the command block any of the following commands search home preset initialize home Figure 4 9 Axis Position Scale 110 12 MM 10 20 30 40 50 60 70 80 90 100 0 130 140 150 1 2 3 4 5 6 INCHES A 17967
68. side of the supply voltage to pin E of the encoder With this configuration 5V dc power is generated at the encoder the signals from the encoder are 5V dc 6 27 Chapter 6 Installing the Assembly Figure 6 16 Connections to a Cat No 845N SJDN4 C Encoder and a Bulletin 1388 dc Servo Controller Drive 1771 ES Expander 8 to 15V dc Power Supply for Input Circuits CJ customer supplied x LJO Cat no 845N aes ESSE SJDN4 C Encoder Qi 1 F 9 E 10 5 ox B 9 H S EN O 7 aS ailli NET Bot S d r BS 8 Bulletin 888 C471 cr c DC Servo ded 913 Controller JS gt 27 5 Drive Sd QA ils Q3 I B ssl xd CRM m 7 p EA Ly Q 15 F 14 r Motor Tach 10 17764 NOTES i Ell Belden 8725 or equivalent 50ft max Belden 8761 or equivalent 50 max T P2 Bulletin 1388 Power Transformer 12303 Connect the bulletin 1388 dc servo controller drive and its bulletin 1388 power transformer to the 1771 ES expander as shown in Figure
69. the data blocks entering the program and integrating each axis you start up the system in the following sequence 1 De energize the CRM relay 6 31 Chapter 6 Installing the Assembly Summary 6 32 2 Turn on the dc power connected to the wiring arms 3 Turn on the power supply for the I O chassis backplane 4 Energize the CRM relay 5 Generate a reset command through the command block Now that you have installed the servo positioning assembly you are ready to enter data blocks into the data table of the PC processor During installation you made hardware selections to direct module operation In chapter 7 we tell you how to make software selections to direct other aspects of module operation Chapter Objectives Relationship of Data Blocks Formatting and Interpreting Data Blocks The previous chapter told you how to install the modules During installation you made hardware selections through switch and jumper settings These hardware selections direct some aspects of module operation This chapter tells you how to make software selections through data blocks you set up in the data table Through data blocks you direct module operation This chapter also tells you how to monitor module operation through a data block that the module sends to the data table You must program the PC processor to communicate with the 1771 M3 controller through a block transfer read instruction and a block transfer write
70. the analog velocity command signal to the servo drive Figure 4 1 Where the Servo Positioning Assembly Fits in a Positioning System Axis Motion Servo Positioning Assembly Encoder Ee sd orwar as f cu Tach Cuca Position Following Velocity Servo Drive e Command Error Command Feedrate gt gt 1 E Velocity Feedback Position Ve x Incremental Position Feedback 12005 Figure 4 2 shows where the servo positioning assembly fits in a PC system The PC processor constantly communicates with the servo 4 1 4 Positioning with Allen Bradley PC PC Processor positioning assembly through the I O scan The PC processor acts on a block transfer read instruction to receive status blocks Based on the status information received the PC processor acts on a block transfer write instruction to send either parameter blocks move blocks or control blocks Figure 4 2 Where the Servo Positioning Assembly Fits in a PC System Output Scan Outputs Parameter Moveset and Command Blocks Independent of I O Scan Move Moveset 4 2 Servo Positioning Input Scan Assembly Inputs Status Blocks 12006 Although the servo positioning assembly sends data to and receives data from the data table
71. the drive disable connections or the servo drive Adjust the battery box output to zero The close the switch to the drive disable line If the motor starts to accelerate the leads from the tachometer to the servo drive are reversed or disconnected If the motor rotates without acceleration you may need to adjust the drive balance refer to the servo drive manufacturer s instructions Disconnect power to the servo positioning assembly and servo drives Remove servo drive fuses to ensure that the servo drives are disabled Connect the servo motor to the leadscrew Chapter 9 Integrating Axes 15 Replace the axis drive fuses then re apply axis and servo positioning assembly power Leave de energized those drives for axes you are not integrating 16 While holding the switch in the drive disable line closed adjust battery box output to move the axis slowly in each direction Check for correct wiring of the analog output leads Positive command voltage must move the axis in the positive direction Negative command voltage must move the axis in the negative direction If phasing is incorrect reverse the command connections either at the servo drive or at terminals 3 and 4 of the right servo expander wiring arm not both CAUTION Keep the axis near its center of travel Running the axis into its mechanical stops could damage equipment If you inadvertently run an axis far enough that it trips an overtravel limi
72. the following error If following error is not the same as that recorded in step 9 lower one of the D A voltage values in the parameter block to compensate Repeat this step to verify the correction Following error should be the same for both directions 9 7 Chapter 9 Integrating Axes Tachometer Calibration 9 8 11 12 Observe following error for axis motion in both directions at various speeds by jogging the axis At each speed following error should be the same for axis motion in both directions Jog the axis back and forth within its range of travel Use feedrate override to vary axis speed Verify that axis motion is smooth and stable at all speeds including rapid traverse in both directions If it is not check parameter block values for initial gain in position band gain break speed and gain reduction factor These parameters can influence axis stability and positioning accuracy and may require minor adjustment at this point If necessary adjust the servo drive according to the manufacturer s instructions to obtain the desired results Repeat this closed loop integration procedure for each axis For the loss of feedback detection feature to function correctly you must calibrate the 1771 ES expander Follow these steps 1 Turn on bit 15 enable loss of feedback detection of the home position value word in the parameter block word 17 for axis 1 word 36 for axis 2 word 55 for axis 3 WARNING O
73. to be 0 5 program 50 as the value for gain reduction factor Gain Reduction Factor 50 1 The gain reduction factor must be less than 1 0 If you program zero the system gain for any axis speed will be the initial gain If gain break velocity is zero and you program a non zero gain reduction factor system gain for any axis speed is the initial gain times the gain reduction factor Enter the gain reduction factor in BCD format In Position Band The size of the in position band is measured in increments of the feedback resolution of the axis Program a 2 digit BCD value that is half the desired in position band in bits 10 17 of the in position band and gain break factor word Figure 7 17 If you program zero as the in position band parameter value the servo positioning assembly automatically makes the active in position band 2 feedback increments The 1771 M3 controller turns on the in position bit when the done bit is on in the status block and the axis is within the in position band The axis must be in position before the following actions can take place Manual mode commands are not executed unless the in position bit is on n auto mode the start command is not executed unless the in position bit in the status block is on 7 27 Chapter 7 Formatting and Interpreting Data Blocks 7 28 When the direction of axis motion is reversed the in position bit in the status block must be on before axis motion
74. too small for selected rapid rate 14 Rapid rate entered exceeds 250 kHz maximum input frequency 15 Rapid rate entered exceeds 1 2 revolution of encoder 2 4ms 16 Programmed velocity rapid rate 17 Invalid velocity exponent programmed escape move blocks Command results in overflow of offset accumulator Attempted context switch while axis is commanding motion Manual mode only bit s on while in auto mode Chapter 7 Formatting and Interpreting Data Blocks Invalid motion command bit combination or command not allowed 33 Invalid command cannot process new parameters preset or offset commands while axis is in motion Attempted switch to auto mode before first marker is found Parameter Block Through the parameter block you specify axis parameters such as software travel limits home position value servo gain and rapid traverse rate You specify these parameters for each axis individually Figure 7 8 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 8 Parameter Block Showing Word Assignments 1 Parameter Block Control Word 2 Parameter Block Pointer 3 Command Block Pointer Fixed 4 Moveset Block Pointer Axis 1 Overhead 5 Moveset Block Pointer Axis 2 6 Moveset Block Pointer Axis 3 7 Feedback Resolution A 8 Encoder Lines 9 Feedback Mult Encoder Lines Mult Initial Gain 10 Gain Break Speed In Position Band Gain Reduction Factor 12 Rapid Trave
75. values are zero there are no software travel limits To guard against damage to equipment exercise caution when operating an axis without software travel limits 11047 Backlash Takeup Backlash takeup helps minimize axis positioning inaccuracy caused by mechanical play in the axis positioning system Word 23 42 61 is the backlash takeup word Figure 7 26 7 36 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 26 Backlash Takeup Word Backlash Takeup Distance Word 23 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 42 Axis 2 Word 61 Axis 3 inch metric decimal decimal point point vs Sign Distance axis overshoots when initial 024 approach to endpoint is from direction 1 opposite that specified in bit 17 Axis approaches all endpoints moving in the direction specified by the sign bit 17 11048 In this word bit 17 specifies the direction the axis is to move in approaching all programmed endpoints When the axis approaches an endpoint at which it is to stop while moving in the specified direction it simply stops at the endpoint If the axis approaches the endpoint from the opposite direction it overshoots the endpoint by the amount you specify in bits 00 thru 16 then returns to the endpoint from the opposite direction Consider the example of your entering 4 0010 in the backlash takeup word Ifthe ax
76. which could for example be applied to a conveyor Figure 4 8 4 7 4 Positioning with Allen Bradley PC Figure 4 8 Moveset Profile for Constant Velocity Moves Rate gt Position 12009 In Position For a continuous move with the next move in the same direction the move is complete when the axis feed is done The 1771 ES expander immediately begins the feedrate for the next move without waiting for the following error to close For any halt move single step move or a continuous move with the next move in the opposite direction the move is not complete until the axis is in position The axis is in position when the following conditions are met the axis feed is done following error has closed to within the in position band You establish the in position band in the parameter block The in position band is the largest distance from the endpoint at which you will allow the axis to be considered in position Synchronizing Axes In many applications it is important to synchronize the motion of two or more axes In the following sections we will tell you how to do this Halt Moves For halt moves axis synchronization is straightforward When an axis is in position after a move the next axis move will not begin until you send a start command 4 8 4 Positioning with Allen Bradley You can monitor the in position signal of each axis through the status block When
77. will not execute immediately This would cause an unintended delay for run moves Bit 13 Initialize Home In the manual mode turn on bit 13 to generate an initialize home command This command is functional only when the servo positioning assembly is in the manual mode and the axis is stopped The status block indicates a programming error if you issue the initialize home command while the axis is moving To execute this command the servo positioning assembly sets the axis current position register to the home position value in the parameter block and clears any accumulated offsets Bits 17 thru 14 Control Word 1 ID Set bits 17 thru 14 to 1100 to identify this as axis control word 1 If the control word 1 ID bits for any of the axes are incorrect the status block indicates a programming error for the axis with the incorrect ID and all axes execute slide stops Axis Control Word 2 Figure 7 44 shows axis control word 2 Bits 12 and 14 apply only to the manual mode Chapter 7 Formatting and Interpreting Data Blocks Figure 7 44 Axis Control Word 2 Axis Control Word 2 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 N 1 Get New Preset Value Feedrate Override 1 Tachometer Binary format Search Home Direction Jog Rate Select le 0 Low 0 1 High L 1 Axis Feedrate Manual Mode On
78. word the servo positioning assembly ignores the programmed deceleration rate and steps axis feed rate directly to zero This parameter is not effective in auto mode and applies only to jog and search home operations Chapter 7 Formatting and Interpreting Data Blocks Figure 7 24 Deceleration Step Rate Word Decel Step Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 20 Axis 1 E Word 39 Axis 2 Word 58 Axis 3 inch metric decimal decimal point point This BCD value 0 999 ipm or 010 x 10 19 99 mmpm max times the 100 x 10 multiplier is the decel step rate 110 10 During deceleration the axis feed 111 x 10 rate steps directly to zero once the rate drops to this level This only applies to jog and search home 11046 Software Travel Limits Words 21 and 22 40 and 41 59 and 60 specify the axis position values of the axis software travel limits Figure 7 25 When a programmed move calls for the axis to move beyond a software travel limit if there is time the servo positioning assembly automatically decelerates the axis at the programmed rate for the current move so that it stops at or before the software travel limit position If there is no time to decelerate the axis before the limit is exceeded the servo positioning assembly executes an immediate stop This could occur following a continuous move because the nex
79. 0 dc 12 S 12 Tachometer 4 12010 5 2 Chapter 5 Hardware Description Outputs to Servo Drive Terminals 3 and 4 on the right wiring arm provide connection points for the velocity command signal to the serve drive This analog output is a 10V dc differential signal Terminals 8 9 and 10 on the right wiring arm provide connection points for a drive disable signal Figure 5 2 In chapter 6 we will show you how to connect this output to either source or sink 100mA maximum to enable the drive The module normally provides current thru this transistor to enable the drive However the module will turn off the current to disable the drive if the hardware stop input goes high a command block commands an immediate stop a firm ware or hardware watchdog timers times out the 1771 ES expander detects excess following error a loss of feedback or a power supply loss Figure 5 2 Schematic Diagram of the Drive disable Output Circuit 1771 ES Expander dg DRIVE 8 DISABLE SUPPLY DRIVE 9 DISABLE 9 OUTPUT DISABLE S 10 nre 10 12011 The 1772 ES expander is compatible with a wide variety of servo drives including Allen Bradley Bulletin dc Servo Controllers refer to publication 1388 5 0 Allen Bradley also offers Bulletin
80. 0000000000000 R CTRL WORD E 0000000000000000 13 Consider a servo positioning assembly that controls the motion of two axes Figure 8 11 Figure 8 12 and Figure 8 13 show three moveset profiles Assume that you are to program these profiles for execution by axis 1 When the servo positioning assembly receives a start command via the command block it is to execute movesets 1 2 and 3 in sequence Axis motion is to stop after execution of moveset 3 is completed Figure 8 14 shows a single moveset profile Assume that you are to program this profile for execution by axis 2 After axis 2 performs move block 2 of its moveset a two second dwell it is to wait until it receives a start command via the command block to execute move block 3 8 21 Chapter 8 Figure 8 11 Profile of Moveset 1 for Axis 1 Rate Move 1 Move 2 Move 3 Move 4 5 ipm Rate Final Rate Final 1 Rate 125 Acc 50 100 Final Rate Final Acc Dec Rate Dec 50 25 0 Dec Nj Acc 4 6 8 10 Position Dec Acc 150 Final Rate Rate Move 6 11059 8 22 Chapter 8 Figure 8 12 Profile of Moveset 2 for Axis 1 Rate ipm 160 140 120 Move 1 100 80 60 wel P d 40 Acc Dec 100 ipm s Move 2 2 Second Dwell 20 2 0 Position 9 1 2 3 4 Inches 40 60
81. 1 2 or 4 EL encoder lines per revolution Here is a list of specifications for the servo positioning assembly Servo Output Voltage 10 dc maximum isolated D A Converter DAC Signed 12 bit resolution Encoder Input High 1 6V Low 1 0V sinking Encoder Input Rate Differential 250k Hz maximum Single ended 20k Hz maximum Jumper selection of differential or single ended input Encoder Multiplier xl x2 or x 4 programmable Tachometer Input For loss of feedback detection Full scale voltage 3V dc minimum 50V dc maximum Input impedance 20k ohmss Discrete Inputs 5 11 Chapter 5 Hardware Description 5 12 Resistance to high side of supply 11 2k ohms or 1 2k ohms switch selectable for each input For alow required sink current with 1 2k ohms resistance 4mA 5V 24mA 30V For a low required sink current with 11 2k ohms resistance 0 4mA 5V 2 7mA 30V High 4096 of dc supply voltage low 20 of dc supply voltage Hardware Done Output On 15V source thru 1k ohms resistance Off 15mA sink Drive Disable Output Current 100mA maximum source or sink Voltage 30V dc maximum to 5V dc minimum Backplane Current 1771 M3 controller 1 75A 1771 ES expander 1 70A External Power Supply Requirements External supply for inputs 4 75 dc minimum 30V dc maximum 500mA maximum External supply for DAC and hardware done output
82. 1 OZ module controls whether the input is high or low You can use the ladder diagram program to generate a hardware start signal by closing the contacts of 1771 OZ module output when each of several axes generates a hardware done signal You can connect the same hardware start signal to several 1771 ES expanders to coordinate the start of motion following halt moves for these axes Connecting a Differential Encoder Figure 6 10 shows details of how to connect a differential encoder With a differential encoder reversing the connections on a channel or changing the position of the polarity jumper for the channel reverses the polarity of the signal on that channel Set the polarity so that the marker is true at the same time that channels A and B are true If you switch channel A with channel B you reverse the direction of the feedback If the direction of the feedback does not correspond to the axis motion direction as you have defined it switch channel A with channel B Ground the shield at the I O chassis end 6 19 Chapter 6 Installing the Assembly Figure 6 10 Connection Details for a Differential Encoder 5 to 30V DC Belden 8761 or Input Power equi Supply quivalent 50 ft max customer supplied aN Ground the shield i at the I O chassis end
83. 11 10 07 06 05 04 03 02 01 00 Word 7 Axis 1 Word 26 Axis 2 Word 45 Axis 3 Feedback resolution format 0010 minimum 0 inches x 10 1 millimeters x 10 C 2 Parameter Block App Encoder Lines 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 8 Axis 1 Word 27 Axis 2 Word 46 Axis 3 E The value of this word times the mulitplier specified by bit 15 of the next word must equal the actual number of encoder lines BCD format For 10 000 program 0000 Feedback Multiplier Encoder Lines Multiplier Loss of marker Initial Gain 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 9 Axis 1 Word 28 Axis 2 Word 47 Axis 3 Y Loss of marker Feedback detection Multiplier 0 disabled 01 2x1 1 enabled 10 x2 Encoder E Em 1 00 x4 Lines _ Initial Gain ipm mil or Multiplier mmpm mil BCD format id 1 mil 0 001 inch or 0 001 See preceding millimeter word Gain Break Speed 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 10 Axis 1 n Word 29 Axis 2 Word 48 Axis 3 inch n metric decimal decimal MAKE point point 1 x1 This BCD value 0 999 ipm or 010 x 10 19 99 mmpm max times the l 0 X g multipl
84. 17 Continuous If you turn on bit 17 and turn off bit 16 the move blends smoothly with the next move That is the axis accelerates or decelerates from its final feedrate to the final feedrate of the next move Figure 7 35 shows a moveset profile with examples of various bit 16 bit 17 combinations Table 7 C explains the various combinations with reference to the figure Position Words Two position words follow the SMCW in each move block Together these words specify an axis motion endpoint a position preset value or a dwell time depending on the move block type entered in bits 11 10 and 6 of the SMCW Figure 7 36 7 55 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 36 Position Dwell time Words Most Significant Position Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 E 0 absolute Most significant digits 1 incremental inch rig 1 3 BCD home position value 999 9999 inches or 19999 999 mm max or dwell time value 9999 999 s max Least Significant Position Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 metric seconds Least significant digits 11020 For dwell values these words express a 7 digit number in BCD format The maximum programmable value is 9999 99 seconds The minimum programmable value is 0000 020 seconds For inch values these words express a 7 digit number
85. 3 Status Word 2 Axis 3 MS Position FE Diagnostic Axis 3 LS Position FE Diagnostic Axis 3 11215 We reserve the first word of the status block for future use It contains all zeros when returned by the 1771 M3 controller The second word is an address pointer that identifies the next block the processor is to transfer to the 1771 M3 controller Words 3 thru 6 provide the status of axis 1 Words 7 thru 10 provide the status of axis 2 Words 11 thru 14 provide the status of axis 3 The following sections describe status block words The servo positioning assembly configures all words in the status block Address Pointer The address pointer word Figure 7 3 contains in BCD format the data table address of the next block to be transferred from the processor to the 1771 M3 controller Your ladder diagram program reads this address and uses it to configure a write block transfer instruction The 1771 M3 controller programs this word according to its requirements When it does 7 5 Chapter 7 Formatting and Interpreting Data Blocks 7 6 not need to request the parameter block or a moveset block it requests the command block Figure 7 3 Address Pointer Word Address Pointer Word 2 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Address of next block to be write transferred to the 1771 M3 controller BCD format 11052 The value that appears in this word is one of the pointer addresses you put
86. 4 03 02 01 00 Word 6 Axis 1 Word 10 Axis 2 Word 14 Axis 3 metric decimal Least significant digits 11055 point Turn off bit 11 and turn on bit 15 to display the following error as shown in Figure 7 6 The maximum value is 999 9999 inch or 19999 999 mm If the axis exceeds the maximum it displays the maximum Turn on bit 11 to display the diagnostic status as shown in Figure 7 7 Word 5 Axis 1 Word 9 Axis 2 Word 13 Axis 3 Word 6 Axis 1 Word 10 Axis 2 Word 14 Axis 3 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 7 Position Following Error Diagnositc Words with Diagnostic Selected First Diagnostic Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word pointer This BCD Error code This BCD number tells you which word is number refers to the error in error within the block listed in Table 7 A Second Diagnostic Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 YO cc Block pointer This BCD number is the address of the block which is in error 12028 Also this diagnostic status displays automatically when the 1771 M3 controller detects an error in the parameter block immediately after power up or an invalid ID in a command block The diagnostic status displays automatically in that case because the error prevents your selecting it through the command block
87. 7 d 111 110 00 07 110 110 HM M Jog Start ns VI g y Rung 8 01 07 111 110 1L dL 1 01 07 110 110 Preset Begin 200 VI y Rung9 02 07 a 111 110 1E NE 1 L 02 07 110 110 Search Home EOM Stop C17 Rung 10 03 111 110 1E Ji RE ame 03 07 110 110 Go Home Escape s i V I Rung 11 04 07 2 111 110 1L ME lids 04 07 110 Slide Stop yt Rung 12 E 05 110 Software Sto Rung 13 06 110 Auto aay E Rung 14 s 07 116 Get New Preset Value x D Rung 60 17 Axis 1 Movesets Chapter 8 FILETOFILEXOR 0090 Parameter Command Status COUNTER ADDR 0050 EN Rung 61 POSITION 001 17 FILE LENGTH 64 FILEA 0500 0577 0090 FILEB 0600 0677 DN FILER 0700 0777 15 RATE PER SCAN 064 Rung 62 FILE TO FILE XOR pos Axis 2 Movesets COUNTER ADDR0050 EN POSITION 001 17 FILE LENGTH 64 FILEA 0200 0277 FILEB 0400 0477 0050 FILER 0450 0547 DN RATE PER SCAN 064 15 FILETOFILEXOR 0050 COUNTER ADDR 0050 CEN Rung 63 POSITION 001 17 FILE LENGTH 64 FILE A 0300 0377 FILEB 1000 1077 0090 FILER 0110 0207 DN RATEPERSCAN 064 15 0051 TON Rung 64 0 1 PR 030 AC 000 Rung 1 L Rung 65 Rung 1 assures transfer of the parameter block at power up This rung examines the ready bits 45102
88. Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 26 Axis 2 Word 45 Axis 3 Feedback resolution BCD format 0010 minimum O inchesx10 1 millimeters x 10 11033 7 21 Chapter 7 Formatting and Interpreting Data Blocks 7 22 Encoder Lines This word specifies the number of encoder lines per encoder revolution Figure 7 12 Figure 7 12 Encoder Lines Word Encoder Lines 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 8 Axis 1 Word 27 Axis 2 Word 46 Axis 3 The value of this word times the mulitplier specified by bit 15 of the next word must equal the actual number of encoder lines BCD format For 10 000 program 0000 11034 The value of this word times the encoder lines multiplier specified by bit 15 of the next higher word must equal the actual number of lines on the encoder You can enter values up to 10 000 with the x1 multiplier Entering zero 0000 specifies 10 000 lines You can enter higher values by using the x4 multiplier For example if your encoder has 12 000 lines you can enter 3000 in the encoder lines word and turn on bit 15 of the next word to indicate x4 3 000 x 4 12 000 lines The status block indicates a programming error after transfer of the parameter block if Encoder Lines x Feedback Multiplier x Encoder Lines Multiplier gt
89. Be Oo HDW DONE l 9 9 0 S 12012 The output transistor normally on provides a 15mA maximum sink When the axis feed is done and the axis is in position the transistor is off and the circuit provides 15 dc through resistor This provides you with a hardware done signal that is high true In chapter 6 we will show you how to connect the hardware done signal to a dc 12 24V Input Module cat no 1771 IB for axis synchronization of halt moves Discrete Inputs Terminals 8 9 10 and 11 on the left wiring arm provide connection points for discrete input signals The module accepts a discrete input signal as being high when it reaches 40 of the input power supply voltage The module accepts a discrete input signal as being low when it reaches 20 of the input power supply voltage 5 5 Chapter 5 Hardware Description 5 6 Each discrete input has an internal pull up resistor In chapter 6 we will show you how to select an internal pull up resistor of 1 2k or 11 2k You select each input individually through a switch setting For a high signal the input device you connect to a discrete input does not have to source current For a low signal the input device you connect to a discrete input has to sink current through the pull up resistor Hardware Start In the auto mode the module accepts a high to low transition at terminal 8 of the left wirin
90. Current Sink A signal sending device that shunts current to ground Current Source A signal sending device that generates positive current Data Table The part of processor memory that contains I O values and files where data is monitored manipulated and changed for control purposes Digital Representation of data in discrete numerical form Digital to Analog D A Conversion Production of an analog signal whose instantaneous magnitude is proportional to the value of the digital input Encoder Incremental A rotary device that transmits a fixed number of pulses per revolution Feedback The signal or data transmitted to the PC from a controlled machine to denote its response to the command signal Feedback Device An element of a control system that converts linear or rotary motion to an electrical signal for comparison to the command signal e g encoder Feedback Loop A closed signal path in which feedback is compared with the commanded value to obtain a corrective error signal Feedback Resolution The smallest increment of dimension that the feedback device can distinguish and reproduce as an electrical output Feedback Signal The measurement signal indicating the value of a directly controlled variable which is compared to the commanded value to obtain the corrective error signal Feedforward Control Action in which information concerning upstream conditions is converted into corrective commands to minimize t
91. PC attempts to transfer processor work area words to the 1771 M3 controller the PC can lock up out of communication with the 1771 M3 controller For PLC 2 family processors store blocks at data table addresses above 200g and no block should begin less than 64 words from the start of the user program 8 4 Figure 8 3 Chapter 8 Block transfer read instruction Example PLC 2 30 or Mini PLC 2 15 uote c 324 010 Output R Data Table moe 1 Block length code 012 017 027 1 2 1 030 Timer Counter Accumulated Area 060 Block Transfer Data 067 110 Input B Image 1 112 Table 117 Timerl 0 6 0 130 Counter Preset Area EE CUPS IT n a n 113 BLOCK XFER READ 02 DATA ADDR MODULE ADDR BLOCK LENGTH FILE Output Image Table Byte contains Read Enable Bit and Block Length in binary code Data Address contains Module Address in BCD First file word Last file word Input Image Table Byte contains Done Bit Storage location of file address in BCD R Bit 17 READ 012 EN 17 112 DN 17 030 121 00 060 067 11057 8 5 Chapter 8 PLC 2 Family Block Transfer Timing 8 6 Because the servo positioning assembly relies on bidirectional block transfer for communication with the PC processor the time required for block transfer operations may be crit
92. Programming No of Words Comments 1 Move Block MCW Separate words required to program Local Feedrate Bit 15 1 Local Acc Dec Local Accel Local Decel Position MSW pee SMCW 2 Bit 14 1 Local Rate Bit 15 0 Global Acc Dec Separate word required to program Local Feedrate Position MSW No moveset words required to program Accel and Decel values programmed in parameter block are used Position LSW Local Feedrate SMCW 3 Bit 14 0 Global Rate No Moveset words required to program Feedrate Bit 15 0 Global Acc Dec Accel and Decel values programmed in parameter block are used Position MSW No Moveset words required to program Feedrate Accel or Decel values programmed in parameter block are used Move 3 Position LSW SMCW 4 Bit 14 0 Global Rate Separate words required to program Local Accel and Bit 15 1 Local Acc Dec Local Decel 7 51 Chapter 7 Formatting and Interpreting Data Blocks No of Words Comments Position MSW No Moveset words required to program Feedrate value programmed inn parameter block used Position LSW Next Moveset Pointer This word is optional Bit 16 Run Halt Bit 16 determines whether or not the move block after this one will execute automatically without a motion command start next move or begin from the command block Bit 16 functions in conjunction with bit 17 single step continuous Run If you turn off the run halt bit the servo position
93. Publication 1771 6 5 25 October 1985 PN 955098 32 Supersedes 1771 832 August 1994 Copyright 1986 Allen Bradley Company Inc Printed in USA
94. Search Home Because the position feedback is incremental rather than absolute the servo positioning assembly does not know the axis position when it first receives power You must command a search home through the command block each time after powering up In the search home operation the axis moves until the servo positioning assembly detects the first encoder marker beyond the user installed home limit switch The 4 11 4 Positioning with Allen Bradley PC axis stops on the marker The servo positioning assembly then sets it position register to the home position value you specify in the parameter block This initializes the axis position scale Figure 4 10 shows how the home position value you specify in the parameter block can affect the axis position scale This figure compares the scales for an axis after search home operations with different home position values form the parameter block representing the same physical position Figure 4 10 Axis Position Scales for 2 Home Position Values Home 2 0 3 00 9 Parameter Block Home Position Value 3 00 10 5 00 0 1 Parameter Block Home Position Value 5 00 11008 Preset Through a command block you can command the servo positioning assembly to preset a specified value into its position register When the servo positioning assembly executes a preset command it sets its position register to the specified
95. The second diagnostic word is the block pointer The block pointer is a BCD number that indicates the starting address of the block in error The 1771 M3 controller gets these block pointers you enter into the parameter block or the moveset block The high byte bit 10 thru 17 of the first diagnostic word is the word pointer The word pointer is a BCD number 1 thru 64 that indicates which word is in error within the block The low byte bits 00 thru 10 of the first diagnostic word is the error code The error code is a BCD number that references the errors listed in table 7 A Chapter 7 Formatting and Interpreting Data Blocks 7 16 Use the block pointer and word pointer to identify the location of the problem Then use the error code to determine the nature of the problem Table 7 A Diagnostic Code Definitions Code Definition 01 Invalid block identifier 02 Non BCD number entered Invalid bit setting unused bits must be zero MS metric only bit set in inch format Overflow Converted data is too large for internal registers Can only change feedback multiplier from a power up rest 07 Invalid axes used programmed Invalid write block address points 00 Invalid feedback resolution 0 00001 in 0 0001 mm Invalid feedback multiplier bit setting 11 Counts per rev x feedback mult x encoder lines mult gt 32767 decimal 12 D A voltage too small for selected rapid rate 13 Initial gain
96. Word 1 Axis 1 2 Control Word 2 2 Control Word 2 Axis 1 3 Position Preset MS Word 3 Control Word 1 Axis 2 4 Position Preset LS Word 4 Control Word 2 Axis 2 5 Control Word 1 Axis 3 6 Control Word 2 Axis 3 7 Position Preset MS Word Axis 1 b Two Axis 8 Position Preset LS WOrd Axis 1 Word Control Word 1 Axis 1 9 Position Preset MS Word Axis 2 2 trol Word 2 Axi 10 Position Preset LS Word Axis 2 3 Control Word 1 Axis 2 11 Position Preset MS Word Axis 3 4 e Control Word 2 axis 2 12 Position Preset LS Word Axis 3 5 Position Preset MS Word Axis 1 6 Position Preset LS Word Axis 1 7 Position Preset MS Word Axis 2 8 Position Preset LS Word Axis 2 1 Appendix Command Block Axis Control Word 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 11 0 0 A Auto Manual Control Word 110 Me Move Jog Auto Manual Start Jog Initialize Beain Home g un EOM earcl Moveset New Override Parameter Stop Home Offset Escape GoHome Slide Reset Stop Software Stop 1 Auto Mode 0 Manual Mode Axis Control Word 2 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
97. a loss of feedback it turns on the loss of feedback bit in the status word If this bit is on then the immediate stop bit in the status block is on indicating that the 1771 ES expander has executed an immediate stop after detecting the loss of feedback Bit 17 Excess Error If following error equals or exceeds the excess following error value you enter in the parameter block the 1771 M3 controller turns on this bit Since excess following error turns on immediate stop the immediate stop bit in the status block is also on Additionally if the 1771 ES expander applies feedrate reduction to an axis for which excess error is greater than the 106 25 built in excess error value then the feedrate reduction bit bit 12 of the first status word for the axis is on If however the excess error point you enter is less than 106 25 then the feedrate reduction bit is not on Second Status Word The second status word Figure 7 5 identifies the active moveset and move as well as providing additional status bits from the function of the corresponding bits for the series A servo positioning assembly If you replace a series A assembly with a series B assembly without changing your program accordingly you may cause unexpected results A CAUTION The function of bits 06 16 and 17 are different Chapter 7 Formatting and Interpreting Data Blocks Figure 7 5 Second Status Word Second Status word
98. ach moveset block you must include the address pointer for the next moveset block if one exists for the axis 8 1 Chapter 8 8 2 Once it has a moveset block for each axis unless it is down to the last two moves the 1771 M3 controller normally requests the command block through the status block Figure 8 1 Data Blocks Sent to the 1771 M3 Controller Showing Where Address Pointers are Given Parameter Block Contains address pointer for parameter block command block first moveset block axis 1 first moveset block axis 2 first moveset block axis 3 Command Block First Moveset Block Axis 1 Contains address pointer for the second moveset block axis 1 Second Moveset Block Axis 1 Contains address pointer for the third moveset block axis 1 When it gets down to its last two moves of a moveset the 1771 M3 controller requests another moveset block After the parameter block is sent your program must use the address pointer from the status block to direct the block transfer write instruction so that the requested block always transfers to the 1771 M3 controller For detailed information on programming block transfer instructions refer to the appropriate programming manual as listed in our Publication Index publication 499 PLC 2 Family Block Transfer Instructions Chapter 8 Figure 8 2 shows the formats of block transfer instructions for Mini PLC 2 15 and PLC 2 30 controll
99. aded feedrate override value to change speed on several axes simultaneously an orderly shutdown of the servo system and to provide you with this diagnostic information to allow you to reduce following error by up to 99 9 without increasing instability runs an axis continuously at a selected velocity could apply to controlling a conveyor with no programmed end point Modifies a moveset while it is being executed provide your ladder diagram program with access to diagnostic information hardware and program troubleshooting Chapter 2 Introducing the Servo Positioning Assemb ll These features are only available on the series B servo positioning assembly Summary This chapter was intended to be very general Upcoming chapters cover these topics in greater detail To prepare for those details read about positioning concepts in chapter 3 2 7 Chapter Objectives Closed Loop Positioning Positioning Concepts This chapter presents positioning concepts and terminology If you are thoroughly familiar with the concepts of closed loop servo positioning you can skip ahead to chapter 4 Closed loop positioning is a precise means of moving an object from one position to another Typically an electric motor supplies the mechanical power and the needed motion is linear Therefore we must convert the rotary motion of the motor s shaft to linear motion Axis Motion One common method of converting rotary motion
100. alling the Assembly 6 12 Within a shielded cable pairs of wires are twisted together Using a twisted pair for a signal and its return path provides further protection against noise We show a twisted pair like this XX We show a shielded twisted pair like this XX K Connect each shield to ground at one end only At the other end cut the shield foil and drain wire short and cover them with tape to protect against their accidentally touching ground Keep the length of leads extending beyond the shield as short as possible Use cables with the proper number of individually shielded twisted pairs as follows Number of Individually Shielded To connect to Twisted Pairs Encoder Belden 8725 or equivalent Analog power supply Belden 8723 or equivalent All other shielded cable 1 Belden 8761 or equivalent connections Connecting the Input Supply To connect the input power supply follow these steps 1 Connect the plus side of the input power supply to terminal 1 of the left wiring arm Chapter 6 Installing the Assembly 2 Connect the minus side to terminal 12 and to ground at the I O chassis 3 Connect the shields of the two cable segments if you use the same supply to power the encoder 4 Connect the shield to ground at the I O chassis end 5 Connect the power supply chassis to ground Connecting Hardware Stop Before you connect to the hardware stop input y
101. and 45502 in the status block The parameter block file address 200 is stored as a constant in storage word 0043 At power up the parameter block automatically transfers to the 1771 M3 controller If the parameter block is valid the 1771 M3 8 35 Chapter 8 8 36 controller turns on the ready bits 45102 and 45502 in the status block thus inhibiting rung 1 Rung 2 If both axes are ready bits 45102 and 45502 both on this rung gets the address pointer in the second word of the status block 0450 and puts it in the file address word 0141 for the write block transfer instruction The address pointer in the status block contains the address for the parameter command or a moveset block as requested by the 1771 M3 controller Because of the action of this rung the block of data requested by the 1771 M3 controller is written to the 1771 M3 controller when the write block transfer instruction executes Rung 3 Rung 3 reads the status block from the 1771 M3 controller The data address 0040 is located in the timer counter accumulated area of the data table The module location address 301 indicates that the 1771 M3 controller is in rack 3 module group and the right slot of the module group Block length 00 is the default length This allows the 1771 M3 controller to control the number of words transferred During a read operation data loads into consecutive words starting with the designated address 0447 Rung 4
102. and command blocks 7 2 Chapter 7 Formatting and Interpreting Data Blocks The first block transfer after power up writes a 6 word status block into the data table After that the status block consists of 6 words for a 1 1 system 10 words for a 2 axis system or 14 words for a 3 axis system You establish the address for the status block through the block transfer read instruction Because axis command and status data is stored in the data table axis motion control can interact with other axes discrete I O and report generation Parameter Block The parameter block for a 1 axis system has 25 words a 2 axis system has 44 words a 3 axis system has 63 words You specify parameters for each axis separately You specify parameters such as software travel limits home position Servo gain global accel decel rate rapid traverse rate In the parameter block you also specify the address of the parameter block the command block and the first moveset block for each axis With these addresses the 1771 M3 controller can ask through the status block for the block it needs at any particular time The processor transfers the parameter block to the 1771 M3 controller through a block transfer write This provides axis parameter information after a power up and after a command block commands a reset or new parameters Moveset Block A moveset block describes a sequence of axis moves You can program axis motio
103. apid traverse rate is limited by several parameters The servo positioning assembly detects a programming error and inhibits axis motion when you enter a rapid traverse rate that violates any of the following formulas RR lt 12 500 x FR x FM x EL Table 7 A code 15 1 28 RR 1 5 x 107 x FR x FM Table 7 A code 14 1 28 RR 4 x 106 x FR x D A Table 7 A code 12 RR 6 5 x 107 x FR x IG Table 7 A code 13 1 28 Where the following are parameters you enter RR rapid traverse rate FR feedback resolution FM feedback multiplier 1 2 or 4 EL encoder lines per revolution 7 29 Chapter 7 Formatting and Interpreting Data Blocks 7 30 D A maximum D A voltage IG initial gain These formulas include an allowance for a 127 feedrate override factor These formulas apply to both ipm and mmpm Jog Rate The high and log jog rate words Figure 7 20 specify the speeds at which you can jog the axis You can jog the axis only in manual mode Program the values in BCD format The operator can select jog speed high or low by controlling the jog rate select bit in the command block Figure 7 20 Jog Rate Words High Jog Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Wodi3 istn Word 32 Axis 2 Word 51 Axis 3 inch metric m decimal Multiplier point aai zx 10 This BCD value 0 999 ipm or 010 x 10 19 99
104. ation connect a suppression network for 120V ac Allen Bradley cat 700 N24 fo r220 240V ac Electrocube part no RG 1676 13 12018 6 14 Chapter 6 Installing the Assembly Provide one transformer for the master control relay CRM circuit the loop contactor relay LCR circuit the dc power supplies and any ac I O chassis Provide a separate transformer for the servo drives to provide noise immunity Use normally open LCR contacts to switch power from the servo drive to the servo motor Also use normally closed LCR contacts to switch in the dynamic braking resistor across the servo motor whenever power is removed from the servo motor Check with the servo drive and servo motor manufacturer for the resistance and power rating for the dynamic braking resistor WARNING Without a dynamic braking resistor removing servo motor power while the axis is in motion allows momentum to keep the axis in motion In an emergency situation this could be dangerous A dynamic braking resistor can help stop the servo motor by quickly dissipating the energy of momentum Even with dynamic braking a vertical axis may also require an electric brake or counter balance An extreme overtravel limit switch or an emergency stop switch can de energize the LCR thereby turning off servo motor power However abruptly stopping an axis in this way stresses the servo motor and the mechanical linkage Therefore use the LCR to stop a moving axis only in
105. atting and Interpreting Data Blocks Use bits 16 and 17 of this word to select the feedback multiplier The feedback multiplier you select affects the value you must enter for the feedback resolution word Gain Break Speed At axis speed below the gain break value you enter into the gain break word Figure 7 15 servo gain is the initial gain programmed in the preceding word Figure 7 15 Gain Break Speed Word Gain Break Speed 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 10 Axis 1 P Word 29 Axis 2 N A 7 Word 48 Axis 3 V inch metric decimal docimal Multiplier point point 001 x 10 000 x 10 010 x 10 This BCD value 0 999 ipm or 100 x 10 19 99 mmpm max times the 110 x 10 multiplier is the gain break speed 111 x 10 11037 At speeds equal to and above the gain break value you enter into this word the servo positioning assembly reduces servo gain by the gain reduction factor specified in the next word of the parameter block The gain break plot of Figure 7 16 illustrates the concept of gain break Typically gain at axis speeds below the gain break velocity is relatively high to allow precise axis positioning Reduced gain at axis speeds above gain break velocity allows for better stability at higher axis speeds Gain break velocity can be no greater than rapid traverse rate If there is to be no gain break point for an axis
106. be executed the next move block becomes the current move block Figure 4 4 43 4 Positioning with Allen Bradley PC Figure 4 4 In the 1771 ES Expander as Each Current Move is Completed the Next Move Block is Ready to Take its Place Start Start Start Start Start Start of of of of of of Move Move Move Move Move Move Current Move Block Move 1 Move 1 Move 2 Move 3 Move 20 Move 21 e e o Next Move Block Move 2 Move 3 Move 4 Time gt 12008 Initially the 1771 M3 controller sends the first move block to the 1771 ES expander Then as each move is started the 1771 M3 controller sequentially sends each of the remaining move blocks to the 1771 ES expander A move block for a move to position defines motion of the axis from one position to another Figure 4 5 shows the profile of an axis move The horizontal axis in the figure represents axis position The vertical axis represents axis velocity Moves plotted above the position axis are in the positive direction from left to right moves plotted below the position axis are in the negative direction right to left Figure 4 5 One move Profile for an Axis Rate Move Constant Velocity Final Velocity or Feedrate Acceleration P d Deceleration Position Startpoint Endpoint In the move shown in Figure 4 5 the axis starts from a resting position accelerates to a final velocity 4 4
107. bly As you install it you will make hardware selections to direct its operation to fit your application requirements The first step of installing a servo positioning assembly is to plan how to configure modules in the I O chassis Planning Module Combinations You can install one 1771 M3 controller in an I O chassis together with either one two or three 1771 ES expanders However the I O chassis must not contain any other module combination of a master such as an analog module and its slave expander A master must communicate with its slaves through the backplane Two masters trying to communicate through the backplane interferes with each other If you have an illegal combination of 1771 ES expanders or a second master slave combination in the I O chassis the active indicator on the 1771 M3 controller blinks An illegal combination of 1771 ES expanders would be the number of 1771 ES expanders not matching the number of axes in the parameter block axis 2 with no axis 1 an axis 3 with no axis 2 two axes with the same number Always use the same series level of 1771 M3 controller and 1771 ES expander You cannot use a series A 1771 M3 controller with a series B 1771 ES expander Likewise you cannot use a series B 1771 M3 controller with a series A 1771 ES expander 6 1 Chapter 6 Installing the Assembly 6 2 Avoiding Backplane Power Supply Overload For each module you plan to install in the I O
108. can see from Figure 3 5 that the axis will travel 1 4 inch per revolution if the pitch is 1 4 inch Since leadscrews normally have only one thread and pitch is a more common term than lead in this publication we use the term pitch to refer to the distance the axis travels for each revolution of the leadscrew Do not confuse leadscrew pitch with its inverse which is the number of pitch threads per inch In the example of Figure 3 5 the leadscrew has 4 pitch threads per inch A leadscrew with a pitch of 1 4 inch is often described as being a 4 pitch per inch leadscrew 3 6 Chapter 3 Positioning Concepts Encoder Feedback An incremental digital encoder provides feedback that indicates the magnitude and direction of any change of axis position As shown in Figure 3 6 the encoder shaft is attached to a transparent disc marked with uniformly spaced lines Strategically located photodiodes detect light As the disc rotates the lines break up the light reaching the photodiodes As a result the output channel A channel B and marker from each photodiode is a series of electrical pulses Figure 3 6 Incremental Encoder Showing How Signals Are Generated Photodetectors Light Source Channel A Channel B Marker Marker A B Marker 11000 3 7 Chapter 3 Positioning Concepts Channel Phase Relationship The photodetectors are placed so that the channel A and
109. channel B output signals are out of phase by 90 Figure 3 7 The lead lag relationship of these signals indicates the direction of axis motion Also the phase relationship of these signals allow the decoding circuit to count either 1 2 or 4 feedback pulses for each line of the encoder Figure 3 7 This provides flexibility in establishing feedback resolution Figure 3 7 Encoder Signals Showing Phase Relationship Forward Reverse Channel A Channel A Channel B Channel B Marker Marker 1 7 x1 2 2 1 UOU UUU UUU ad UOU U O UU UU Note For the servo positioning assembly the encoder marker must be high when both channel A and channel B are high or the marker is not recognized unless you set the marker logic jumper to the not gated position 11001 Feedback Resolution The following discussion of feedback resolution assumes that you are using a leadscrew and that the encoder is coupled directly to the leadscrew with no intermediate gearing These assumptions apply to many applications If your application differs be sure to account for the differences Feedback resolution is the smallest axis movement the servo positioning system can detect Itis determined by leadscrew pitch axis displaceme
110. characteristics and determines how the servo positioning assembly interprets the words that follow it Figure 7 33 Figure 7 33 Single Move Control Word SMCW Single Move Control Word SMCW 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 0 0 0 0 0 A A 0 Single step a Lj 1 Continous A 1 Allow feedrate override this move only 0 Run 1 Halt 1 Local feedrate 0 Global feedrate 1 Local acc dec 0 Global acc dec 0 Move to Position 1 Constant Velocity 0 Move to Position with Offset 0 Preset to Position 0 Dwell SMCW ID o oo 11017 7 47 Chapter 7 Formatting and Interpreting Data Blocks 7 48 Bit 7 Allow Feedrate Override With bit 7 on you can enable feedrate override for this move by turning on the axis feedrate override enable bit in the command block The programmed feedrate for this move is modified by the feedrate override value programmed in the command block Feedrate override value is typically an operator controlled input With bit 7 off this move executes at the programmed feedrate regardless of the command block This bit affects only the move controlled by the SMCW For example if feedrate override is to apply to several moves you must turn on bit 7 of the SMCW for each of those moves Bits 11 10 06 Set to 000 Move to Position Turn off bit 11 10 and 6 t
111. ciated figures For all connections to the terminals limit the cable length to 50 feet Keep low level conductors separate from high level conductors This is particularly important for cable connections to the encoder Follow the practices outlined in the PC Grounding and Wiring Guidelines publication 1770 980 Power Supplies Use shielded cable for connecting the input power supply and the analog power supply Route these cables only with low level conductors Keep these power supply cables as short as possible Ground the common terminal for each of these power supplies Encoder and Tachometer For an encoder or tachometer connection use only a single continuous shielded cable segment Do not break the cable for connection in a junction box Connect the cable directly from the encoder to the 1771 ES expander Important Ensure that the power supply for the encoder provides the voltage recommended by the encoder manufacturers Shielded Cables For many connections we tell you to use shielded cable Using shielded cables and properly connecting their shields to ground protects against electromagnetic noise interfering with the signals transmitted through the cables WARNING Use shielded cable where we tell you to use it and how we tell you to use it If you do not the axis motion in your positioning system could be unpredictable this could result in damage to equipment and or injury to personnel 6 11 Chapter 6 Inst
112. ck transfer module whether a read or write operation or the number of words transferred To calculate the I O scan time for block transfer follow these steps 1 Determine the number of active I O channels on the scanner 2 Determine the number of I O channels with block transfer modules 3 Use this table to determine the nominal block transfer time using the number from steps 1 and 2 Chapter 8 Nominal Time ms per Block Transfer Channels with Block Transfer 1 Active 2 Active 3 Active 4 Active Modules Channel Channels Channels Channels 1 40 52 54 58 2 67 68 76 4 Count the number of block transfer modules on the channel If a chassis containing block transfer modules is repeated in the chassis scanning sequence list count the modules as often as listed 5 Count the number of I O chassis entries in the chassis scanning list for the channel 6 Calculate the time between block transfers for the scanner as follows scanner time nominal time x BT modules on the channel I O chassis in list 1 x 9ms Example Computation As an example we compute the read write block transfer time for each of two 1771 MG controllers in the following system User program contains 20K words Channel 1 contains five I O chassis with a total of seven block transfer modules including one 1771 M3 controller Channel 2 contains two I O chassis with no block transfer modules Channel 3 contains two I O chassis with
113. completed the axis begins executing the moveset that was transferred You can issue a slide stop hardware stop or software stop command to stop an escape move in progress When the escape move bit is on the 1771 M3 controller ignores the setting of the end of program bit in the MCW bit 14 Bit 14 End of Program If you turn on bit 14 the 1771 M3 controller stops move execution after it completes execution of the current moveset block The 1771 M3 controller does not look for a next moveset pointer You must issue a begin command to repeat execution of the profile If you issue a start or next move command the 1771 M3 controller turns on the insufficient data bit in the status block The insufficient data bit goes on also if you issue the escape command when no escape move has been programmed However an escape command causes a request for the moveset block identified in the parameter block for the axis Chapter 7 Formatting and Interpreting Data Blocks If the end of program bit is off a start command can start execution of the moveset specified in the next moveset pointer Bit 15 Inch Metric Bit 15 determines how the servo positioning assembly interprets positions feedrates and accel decel rates entered in the moveset block If you want the units Then set bit 15 to be to Single Move Control Word SMCW For each move in a moveset you must enter a single move control word SMCW The SMCW specifies move
114. ction 6 18 Jog Forward Input 5 6 Jograte 7 30 Jog Reverse 5 7 Jog reverse connection 6 17 L Lead 3 6 Leadscrew 3 1 Leadscrew pitch 3 6 Local Accel and Decel Words 7 57 Local Feedrate Word 7 57 local values 4 6 Loss of Feedback 5 9 Loss of power 5 10 Loss of Feedback Detection Enable 7 33 marker 3 10 Marker logic selection 6 7 Module combinations 6 1 move 4 5 move alternatives 4 7 move block 4 3 move selections 4 6 move to position with offset 4 7 move values 4 5 moveset 4 2 Moveset Block 7 40 Moveset block 7 moveset block Next moveset pointer 7 58 0 Offset 7 37 P Parameter Block 7 3 Pitch 3 6 positioning concept 3 1 positioning loop concept 3 3 preset to position 4 7 procedure 9 2 9 6 Programming example 8 21 R Rapid Traverse Rate 7 28 Run single step moves 4 10 S Servo Positioning Assembly 2 1 Servo positioning assembly 4 1 Setting switches and jumpers 6 3 Shielded cables 6 11 single step move 4 6 Software travel limits 7 35 Specifications 5 11 Status Block 7 2 7 4 10 4 Synchronizing Axes 4 8 T tachometer 3 2 Tachometer Calibration procedure 9 8 Index 1 3 Tachometer connections 6 26 V Tachometer conversion factor 7 38 Tachometer input 5 4 Terminal connections 6 10 velocity loop concepts 3 2 Troubleshooting 10 1 Velocity command connections 6 22 velocity comman
115. d is still present after axis motion stops the 1771 M3 controller acknowledges it and executes it The status block indicates a programming error if you change the servo positioning assembly mode from auto to manual or from manual to auto under either of the following conditions f you change the mode while an axis is in motion the status block indicates a programming error and the 1771 M3 controller commands a slide stop The programming error bit clears when axis motion stops If the mode change is still commanded after axis motion stops the mode changes f you attempt a mode change when any of bits 0 thru 4 of the first axis control word or bit 12 of the second axis control word are on the 1771 M3 controller sets a programming error in the status block for the axis If the axis is in motion a slide stop is executed The mode change occurs only after bits 0 thru 4 of the first axis control word and bit 12 of the second axis control word are off and only the command for the mode change is still present Summary In this chapter we told you what information to put into the parameter moveset and command blocks to direct the servo positioning system We also told you how to monitor the servo positioning system thru the status block Now you need to learn how to generate a ladder diagram program to transfer these blocks of information between the data table and the servo positioning system 7 79 Chapter Objectives Programmin
116. d signal 3 2 N Rockwell Automation Allen Bradley a Rockwell Automation Business has been helping its customers improve pro ductivity and quality for more than 90 years We design manufacture and support a broad range Allen Bradley of automation products worldwide They include logic processors power and motion control devices operator interfaces sensors and a variety of software Rockwell is one of the worlds leading technology companies Worldwide representation MA Argentina Australia e Austria e Bahrain e Belgium Brazil e Bulgaria e Canada Chile e China PRC Colombia Costa Rica Croatia e Cyprus e Czech Republic e Denmark Ecuador e Egypt El Salvador Finland France Germany Greece e Guatemala Honduras e Hong Kong Hungary e Iceland e India Indonesia e Ireland e Israel Italy e Jamaica Japan e Jordan Korea Kuwait e Lebanon e Malaysia e Mexico e Netherlands New Zealand e Norway Pakistan e Peru e Philippines e Poland e Portugal Puerto Rico e Qatar e Romania Russia CIS e Saudi Arabia e Singapore Slovakia Slovenia e South Africa Republic e Spain e Sweden e Switzerland e Taiwan e Thailand Turkey United Arab Emirates e United Kingdom e United States e Uruguay Venezuela e Yugoslavia Allen Bradley Headquarters 1201 South Second Street Milwaukee WI 53204 USA Tel 1 414 382 2000 Fax 1 414 382 4444
117. dc power supply between terminals 1 and 12 of the left wiring arm This provides power for the input circuits The input circuits require 500 maximum at 30V You can use the same power supply to power the encoder if the power supply has enough additional current capacity for the encoder Drive Disable Supply Unless the servo drive provides its own dc voltage source for this circuit you ll need a 5 30V dc power supply to provide 100mA maximum for the drive disable circuit How you connect this power supply depends on whether the servo drive requires a current source or a current sink to enable it Analog Supply A separate 15V dc supply is needed to provide 200mA maximum for the digital analog converter DAC to generate the analog output signal and for the hardware done output circuit The servo positioning assembly can be used with PC processors that have block transfer capability and adequate data table size to contain the data blocks you need for your application Compatible PC processors include Mini PLC 2 05 cat no 1772 LS LSP Mini PLC 2 15 cat no 1772 LV PLC 2 20 cat no 1772 LP2 PLC 2 30 cat no 1772 LP3 PLC 3 cat no 1775 L1 L2 Fault Responses Chapter 5 Hardware Description The servo positioning assembly provides a means for detecting and responding to faults in your servo positioning system Since the servo positioning assembly is part of a PC system diagnostic infor
118. der Each line represents 1 250 of a revolution of the leadscrew Also consider a 4 pitch per inch leadscrew for this example The slide moves 1 4 inch for each revolution With an x1 multiplier each feedback increment represents 1 250 of 1 4 inch or 0 001 inch slide movement This is the feedback resolution 0 25 in rev feedback resolution 250 lines rev x 1 increment line 0 001 in increment 3 9 Chapter 3 Positioning Concepts 3 10 Therefore if we cause the leadscrew to move the slide 2 inches we will get 2 000 feedback pulses Now consider replacing the 250 line encoder with a 500 line encoder By doubling the number of feedback pulses per revolution of the leadscrew we improve the feedback resolution from 0 001 inch to 0 0005 inch Another way to improve feedback resolution is to use a higher feedback multiplier You can select a multiplier of x1 x2 or x4 For example with the 4 pitch per inch leadscrew and the 250 line encoder if you select an x2 multiplier you get the same feedback resolution improvement of from 0 001 inch to 0 0005 inch With an x4 multiplier you improve the feedback resolution to 0 00025 inch Marker Besides the channel A and B output an incremental encoder has a marker output Figure 3 6 and Figure 3 7 The marker pulse occurs once every revolution With a 4 pitch leadscrew the marker pulse occurs at each 1 4 inch interval of slide travel We can use a market pulse to estab
119. e wu 8 2k 2 Qi ae O E Right Wiring Arm of Bulletin 1388 1771 ES Expander Servo Drive 12024 Note that whatever configuration your drive requires you must connect the plus side of the power supply to terminal 8 on the right wiring arm of the 1771 ES expander Without this connection the drive disable circuit will not turn on the 1771 ES expander will not enable the servo drive 6 25 Chapter 6 Installing the Assembly Connecting the Tachometer Figure 6 15 shows details of how to connect the tachometer Follow these steps Figure 6 15 Connection Details for Tachometer Right Wiring Arm f 1771 ES Expand Servo Drive 50V Max at Terminals 27KQ High Low High Low v 12025 enon sonny alelelelaleleicialeicle I 1 5 1 Connectthe tachometer directly to the servo drive 2 Connect the tachometer signal at the servo drive to the right wiring arm of the 1771 ES expander This allows the 1771 ES expander to detect loss of tachometer feedback at the servo drive Limit the voltage at the terminals to 50 maximum Tachometers typically generate much larger voltages than 50V at high speed Therefore you must drop the voltage thru a voltage divider 3 Unless you have access to a voltage div
120. e Immediate Stop Home Second Status Word 1 Auto 0 Manual 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 4 Axis 1 Word 8 Axis 2 Word 12 Axis 3 Command token Diagnostic Valid Position Valid Following Error Valid J VV Move Number BCD format Axis Fault B 2 Loss of Power Programming Error Block ID Word 5 Axis 1 Word 9 Axis 2 Word 13 Axis 3 Word 6 Axis 1 Word 10 Axis 2 Word 14 Axis 3 Word 5 Axis 1 Word 9 Axis 2 Word 13 Axis 3 Word 6 Axis 1 Word 10 Axis 2 Word 14 Axis 3 Appendix Position or Following Error Most Significant Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 0 _ _ inch decimal point Sign 0 4 Most significant digits BCD position or following error value 999 9999 inches or 19999 99 mm max Position or Following Error Least Significant Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 metric decimal Least significant digits point First Diagnostic Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word pointer This BCD Error code This BCD number tells you which word is number refer
121. e A move block may have as many as six words a single move control word two position words a rate word an accel word and a decel word In addition two words moveset control word and next moveset pointer apply to the entire moveset block Since the moveset block may contain no more than 64 words the largest possible number of moves a single Chapter 7 Formatting and Interpreting Data Blocks block can describe is 21 21 moves would have to use global accel decel and final rate values Upon request from the status block the PC processor writes a moveset block to the 1771 M3 controller which transfers the move blocks to the 1771 ES expander one at a time The servo expander generates analog voltage to command axis motion as programmed The first word of a moveset block is the moveset control word MCW Following the MCW are the move blocks Each move block consists of a single move control word SMCW two position or dwell words and may contain words for local feedrate accel rate and decel rate depending on whether you select local or global rates by the SMCW You can leave words of zeros before and after move blocks This gives you flexibility For example you could remove a move block without changing the location of the other move blocks within the data table However you must respecify the number of moves in the moveset control word If the end of program bit is off the last word in a moveset block must b
122. e an address pointer in BCD format to the moveset block that should be executed next Moveset Control Word The MCW word identifies the block as a moveset block indicates whether you program the axis in inch or metric units specifies the number of moves in the moveset and whether or not the moveset defines an escape move Figure 7 30 741 Chapter 7 Formatting and Interpreting Data Blocks 7 42 Figure 7 30 Moveset Control Word MCW Moveset Control Word MCW 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 0 0 0 Inch BE A AA Number of moves 1 Endof BCD format 0 Data valid 1 Escape 1 Data not valid move 0 0 1 Axis 1 Odd Moveset 0 106 me 2 eae 0 1 1 Axis3 oveset Moveset Block ID 1 0 0 Axis1 Even Moveset 1 0 1 Axis 2 Even Moveset 1 1 0 Axis3 Even Moveset 11014 Bits 0 thru 5 Number of Moves Bits 0 5 specify the number of moves in this moveset in BCD format Due to the maximum block size of 64 words the maximum number of moves you can program in a moveset block is 21 If you use local rates for any moves the maximum number of moves is reduced To accommodate more moves program additional movesets Bit 7 Data Valid If bit 7 is off it tells the 1771 M3 controller that data in the moveset block is valid and can be executed This bit can be used by the
123. e I O chassis ground bus through 8 AWG wire to the central ground bus to provide a continuous path to ground The tachometer cable is broken into three segments because of the connection to the drive and potentiometer in the middle of the cable Connect these cable shield segments together as shown Connect the shield to ground only at the I O chassis end Do not connect the shield to the drive 6 29 Chapter 6 Installing the Assembly Figure 6 17 Shielded Cable Grounding Connections 15V de 1771 ES For DAC 8 to 15V de Expander C Customer Supplied ME O Return or inp z Twisted pair an with shield supplied or conduit Bulletin 1388 DC Servo Controller Drive 27K Drive Disable Shielded cables are not required for these discrete inputs However they can improve noise immunity 8 AWG wire to NOTES central ground bus Encoder Belden 8761 or equivalent Belden 8723 or equivalent E Belden 8725 or equivalent 12304 Connecting AC Power Figure 6 18 shows ac power connections Incoming ac connects to the primary of the bulletin 1388 power transformer Both the 120V secondary and the 35 5V secondary connect to the bulletin 1388 dc servo controller drive Incoming ac also connects to the primary of an isolation transformer The secondary of the isolation transformer connects to the power supply for the input circuits the po
124. e return to position command would return the axis to the point where it had stopped not the endpoint of the move block Chapter 7 Formatting and Interpreting Data Blocks The status block indicates a programming error if you issue the return to position command with the servo positioning assembly in auto mode Bit 13 Software Travel Limits Override Turn on bit 13 to override software travel limits With the servo positioning assembly in the auto or manual mode and this bit on software axis travel limits in the parameter block have no effect on axis motion This allows axis motion to continue beyond the travel limits CAUTION If values for software travel limits are zero there are no software travel limits To guard against damage to equipment exercise caution when operating an axis without software travel limits Bit 14 Jog Rate Select Bit 14 determines the jog rate for jogs the search home operation and the return to position operation Turn off this bit to select the low jog rate Turn on this bit to select the high jog rate You enter the high and low jog rates in the parameter block If this bit changes state during a jog operation the axis accelerates or decelerates to the newly commanded rate at the global accel decel rate programmed in the parameter block and continues jogging at the newly commanded jog rate During a search home or return to position operation the axis ignores changes in this bit
125. ebruary 1983 Hexadecimal Data Monitor Pr I AxisNo 2 Block DescriptionMOVE SET 1 L ER ES E EE gag E ME hed Data Table Form Example for 2 Axis Program continued Figure 8 15 m Ofr Ce Y O Date 2 22 83 Data Table Addres Position _ FileData Project Name Designer lt ojo UMEN Move 8 31 Chapter 8 You can directly convert between hexadecimal and binary as follows Binary Hexadecimal 0 1 2 3 4 5 6 7 8 9 A B C D E F Hexadecimal digits 0 thru 9 are the same as decimal digits 0 thru 9 Therefore if a word is to contain only a BCD value you can enter the decimal digits directly as hexadecimal digits If you make an individual selection with each bit of a word write down the binary value and convert it to hexadecimal For example binary 1001 1101 0100 0011 converts to hexadecimal 9 D 4 3 If a word is to contain a combination of a BCD value and individual bit selections write down the BCD value fill in the individual bit selections convert the combined binary value to hexadecimal For example if a word is to have bits 17 16 and 15 on plus the decimal value 1972 you would write down the BCD value of 1972 as 1 1001 0111 0010 fill in bits 17 16
126. ed to the channel An I O chassis can appear more than once in a chassis scanning sequence list Count it and the block transfer module s that it contains as often as it is listed 2 Step 2 Using information from Figure 8 6 look up the nominal time from the table in Figure 8 7 Chapter 8 Figure 8 7 Nominal Time Table Step 2 Determine a time from the table Example values have been added Number of Active I O Channels Example Number of active I O channels Number of active I O channels ccontaining one or more block Active I O channels 58 transfer module 2 containing one or more block transfer Time from table 68ms Time ms 3 Compute the approximate transfer time for each block transfer I O channel You will use a value from the table values from your diagram Figure 8 6 and the formula Figure 8 8 Figure 8 8 Channel Time Computation Step 3 Compute the scanner times for each block transfer channel Example values have been added CT Channel Time CT Time x 4 BT modules 1 0 chassis 1 x 9ms table on BT channel on BT channel CT1 68 x 7 b 1 x 9 68 x 7 4 x 9 476 36 512ms Not a block transfer channel 68 x 1 2 1 x 9 68 x 1 1x9 68 9 77ms CT2 Not an active channel CT2 CT3 4 Compute the approximate read write block transfer time for the 1771 M3 controller in channel 1 and in channel Figure 8 9
127. edrate Override Enable e O Jo eaa aaa S pEnpenenergynemnemui9 mme I mE O Bess 2 Manual 12 d L i i Wiring Arm of 1771 OZ Contact Output Module Left Wiring Arm of 1771 ES Expander 12019 In the manual mode the jog reverse switch controls whether the input is high or low In the auto mode the feedrate override enable switch controls whether the input is high or low You can connect the same feedrate override enable signal to several 1771 ES expanders to coordinate the start of feedrate override for those axes Connecting Jog Forward Hardware Start Figure 6 9 also shows details of how to connect jog forward and hardware start Follow these steps 6 18 Chapter 6 Installing the Assembly 1 Connect a third pole of the selector switch to the jog forward hardware start terminal of the 1771 ES expander 2 Connect a momentary contact jog forward switch to the selector switch contact corresponding to manual on the third pole 3 Connect an output terminal of a Contact Output Module cat no 1771 OZ to the selector switch contact corresponding to auto on the third pole In the manual mode the jog forward switch controls whether the input is high or low In the auto mode the hardware start output from the 177
128. ers For each block transfer instruction for these PCs you must specify Data Address The address of a word in the timer counter accumulated value area of the data table This word contains the 1771 M3 controller module location address in BCD format For bidirectional block transfer there must be two data address words in consecutive data table locations one for the write transfer and one for the read transfer These words contain the same module location address Module Address A 3 digit number of the form RGS where R is the rack number G is the module group number and S is the slot number 0 or 1 This value is stored in the data address word Block Length Specifies the number of words to be transferred For the servo positioning assembly program 00 as the block length This is the default value When the PC executes the block transfer instructions the 1771 M3 controller automatically sends or requests the correct number of words File The data table address of the first word in the block to be transferred For read transfer this address 1s constant For the write transfer your program changes the address according to the address pointer in the status block Note that the address of the first word in the block to be transferred is stored in a data table word 1008 above the data address Figure 8 2 also shows enable EN and done DN outputs for each block transfer instructions The PC automatically enters addresses fo
129. es apply to all four 1771 M3 controller modules in the system If the system includes other block transfer modules you will have to make separate calculations for each 4 Calculate the time between consecutive write transfers Since a read transfer occurs between write transfers you must include 2 system scans 4 write transfer times and 4 read transfer times in the formula Time between write transfers 2 PS PIO 4 TR 4 TW 2 24ms 4 0 85ms 4 4 9ms 71105 Mini PLC 2 15 Controller Block transfer timing for the Mini PLC 2 15 controller is similar to that for the PLC 2 30 local system The program scan and processor I O scan are consecutive and are considered as one scan Scan time typically varies from 18 to 24ms per 1K word of user program processor scan time PS z 24ms K word x program length Individual block transfer times can be calculated from this formula T 0 1ms 0 16ms word x block length PLC 3 Block Transfer Instructions Chapter 8 For example consider a Mini PLC 2 15 controller with one 1771 M3 controller in its I O chassis There are no other block transfer modules and program length is 2K words To calculate worst case time between write block transfers for this system follow these steps 1 Write down known values program length 2K words block length 64 write or 10 read 2 Calculate processor scan time PS 24ms K word 2K words 48ms 3 Calculate block t
130. ess pointers to specify word offsets within the file as follows Status 1 10 Parameter 101 144 Moveset Tforans t 201 224 Moveset2forads 1 301 315 Moveset 3 toras 1 401 435 Moveset Tforans2 501 511 Remember that the 1771 M3 controller will not accept an address pointer of 000 Therefore never start a block at word 0 In this example we started the blocks at words 1 101 201 301 401 501 and 601 so that the numbers of their words would correspond to their descriptions in chapter 7 In this example we used a file in the decimal BCD section of the data table to keep the ladder diagram program simple Remember that the 1771 M3 controller will only accept BCD values for address pointers Program Rungs for PLC 3 Chapter 8 Figure 8 17 shows ladder diagram programming rungs for this application for a PLC 3 system The three rungs in Figure 8 17 perform the same function as the first four rungs in Figure 8 16 Figure 8 17 PLC 3 Ladder diagram Programming Example Rungs for Controlling 2 Axes WD050 0003 171 MOV MOVE FROMA TO R 02 WD050 0007 02 WD050 0003 WD050 0007 J A WD050 0102 101 R WB055 0004 0000000011001001 MOV MOVE FROMA TO R 1 L 1 L 02 02 WB055 0000 1 I LAE A WD050 0002 201 R WB055 0004 0000000011001001 BTR CNTL BLOCKXFERREAD EN RACK 003 12 GROUP 0 MODULE 1
131. et value bit in the command block this bit goes on to indicate that the command has been taken When you detect this bit to be you can turn off the command block bit Position Following Error Diagnostic Words The 3rd and 4th status words for an axis provide either current axis position following error or diagnostic information You can select which status to display by controlling the state of bits 11 and 15 of the axis control word 2 of the command block refer to Figure 7 44 and its associated text for more information on Axis Control Word 2 Turn off bits 11 and 15 to display the current axis position as shown in Figure 7 6 The maximum value is 999 9999 inch or 19999 999 mm If the axis exceeds the maximum it displays the maximum and the position valid bit goes off 7 13 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 6 Position Following error Diagnostic Words with Position or Following error Selected Position or Following Error Most Significant Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 5 Axis 1 Word 9 Axis 2 0 0 Word 13 Axis 3 N X inch decimal point Sign 0 Most significant digits BCD position or following error value 999 9999 inches or 19999 99 mm max Position or Following Error Least Significant Word 17 16 15 14 13 12 11 10 07 06 05 0
132. exadecimal values for the parameter moveset and command blocks of this example Note that the axes are independent in this example Axis 1 motion has no effect on axis 2 motion and vice versa 8 25 Chapter 8 Figure 8 15 Data Table Form Example for 2 Axis Program ALLEN BRADLEY Programmable Controller february 1983 Hexadecimal Data Monitor Project Name ____Sample Program 2 Axis ss Page_l_ of 6 Designer Address 200 to 253 Date __2 22 83 Ss AxisNo _1_ amp 2 Description Parameter 1 Data Table Address Position Data Table Address Position 024 024 024 0250 0251 0252 0253 A 8 26 Chapter 8 Figure 8 15 Data Table Form Eample for 2 Exis Program continued ALLEN BRADLEY Programmable Controller february 1983 Hexadecimal Data Monitor Project Name Sample Program 2 Axis Page_2_of_6_ Designer o o o 1 Address20O to 407 Date 2 22 93 AxisNo_1_ amp 2 Block DescriptionCommand Data Table Addresq Position File Data Le 3 0401 2 0402 3 0403 0404 5 D e 5 Ey P 2 2 a D e 5 4 e ESI N N 8 27 Chapter 8 Figure 8 15 Data Table Form Eample for 2 Exis Program continued ALLEN BRADLEY Programmable Controller february 1983 Hexadecimal Data Mo
133. expander power YES Perform a manual jog 4 Check for active stog commands in motio control block 5 Check encoder and encoder wiring Ensure that axis integration has been performed correctly NO Hardware stop indicator on 7 8 Block transfer DONE bits toggling YES Check module address in block transfer Display status block on industrial terminal Is second status word a legal address gy Program error or parameter out of range instructions n YES PELA RUE YES Check parameter word 000 block values Bits 12 11 word 111 10 in 2nd status Error in move set block with i d indicated by value of bits 12 11 and 10 Check command block for illegal bit combinations 11068 OS 10 9 Chapter 10 Troubleshooting Figure 10 5 Troubleshooting Flowchart continued Perform a hardware stop then check for axis motion by monitoring NO IN POSITION following error and axis PONE and PEADY position mn 1 Check encoder and encoder wiring 2 Jog past nearest encoder marker W Does axis jog at both high and low speed YES Perform Search Home or Initialize Home from Home position Do GO Home operation Establish
134. f the status block specifies the starting address of the block to transfer to the 1771 M3 controller Be sure that this address specifies the actual starting address of a parameter moveset or command block If it does not check the corresponding address pointer in the parameter block and make necessary corrections Also check that the parameter block I D bits are correctly programmed bits 10 thru 17 word 1 If they are not the 1771 M3 controller does not accept the parameter block 9 Refer to Table 7 D Note that in some cases ladder diagram execution timing can cause illegal bit combinations to be on 10 11 Chapter 10 Troubleshooting Summary 10 12 10 11 unintentionally In such cases monitoring the command block while executing the ladder diagram program can sometimes help isolate the problem With the axis in hardware stop there should be no axis motion and zero following error If there is axis motion or following error assure that someone has correctly integrated the axis Refer to chapter 9 After system power up the axis jogs only at low speed until the 1771 ES expander receives an encoder marker signal If high jog speed is initially selected thru the command block the axis moves at low speed until a marker is detected then accelerates to high jog speed In this chapter we gave you information that should help you troubleshoot your system As you gain experience with your system the process
135. following functions Processor Communication Fault This red indicator turns on when the module detects a fault in the communication between it and the PC processor The I O adapter module or PC processor will not detect this as a fault Expander Communication Fault This red indicator turns on when the module detects a fault in the communication between it and a 1771 ES expander Active This green indicator is normally on It turns off when a hardware fault is detected on a 1771 ES expander it blinks if you have not properly configured the modules There are six indicators on the 1771 ES expander With the PC processor operating in the run mode the indicators have the following functions Module Active This green indicator is on when the module is operating normally Marker This green indicator is on when the channel A channel B and marker signals are true simultaneously Home This green indicator is on when the axis is in the home position Tach Calibrate This green indicator is used in setting the adjustments for loss of feedback detection Hardware Stop This red indicator goes on when the hardware stop input opens It stays on until the input closes and the servo expander module is reset Diagnostic This red indicator goes on when a fault is detected at the servo expander module 5 1 Chapter 5 Hardware Description These indicators are useful troubleshooting aids described fully
136. ft elden or pO Supplied SO equivalent 50ft max Q Q e 15V dc For DAC T 5 Belden 8761 or li equivalent REM eni Se vargas S0ft max To Servo equivalent Motor 50ft max Ce CH A E S 10V XX CHA i I Unused A TTL CH B E Gi ervo Output CHB ES S Return Drive Encoder Marker ESI S upplied 75 Joc rwolll n 5 ER S Drive Disable Joc REV LES High EE S S Low L O S HOME LS f df GHP 5 to 30V de Drive o 9 gt Disable Supply 9 uq Hard STOP Customer ale idu Supplied 1 4 Belden 8761 or NOTES equivalent 50ft max If equipment permits one supply can be used for encoder and input circuits Current requirements depend on hardware configuration In the auto mode the module accepts this input as the hardware start signal figure 6 9 In the auto mode the module accepts this input as the feedrate enable signal figure 6 9 The module generates a hardware done signal at this 15V dc driver output terminal figure 6 12 E Refer to figures 6 10 and 6 11 Refer to figure 6 8 E Refer to figures 6 13 and 6 14 Refer to figure 6 15 12017 6 10 Chapter 6 Installing the Assembly This is a simplified diagram to give you an overall view of how you are to connect these terminals We give you further details in the following sections and their asso
137. g Objectives Programming The previous chapter told you what information to put into and monitor from the data blocks This chapter tells you how to generate a ladder diagram program to transfer these blocks between the data table and the servo positioning assembly The main objectives of a program for the servo positioning assembly are to transfer the status block from the 1771 M3 controller to the data table transfer the parameter moveset and command blocks from the data table to the 1771 M3 controller You can use a block transfer read instruction to continually transfer the status block from the 1771 M3 controller to the data table You can use a single block transfer write instruction to transfer either a parameter moveset or command block from the data table to the 1771 M3 controller Your program must manipulate the address of the block to be transferred by the block transfer write instruction so that the right block gets there at the right time After power up the first block to send is the parameter block In the parameter block you must include address pointers for Figure 8 1 parameter block command block first moveset block for each axis Once it receives this information the 1771 M3 controller can start to request the block it needs by sending its address pointer in the status block After receiving the parameter block the 1771 M3 controller requests the first moveset block for each axis In e
138. g arm as a low true hardware start input signal After completing a halt move the 1771 ES expander will not execute the next move until it receives a start command The start command could come through block transfer of a control block or through the hardware start signal Feedrate Override Enable In the auto mode the module accepts a high to low transition at terminal 9 of the left wiring arm as a low true feedrate override enable signal After setting a feedrate override value for the axis through the command block and enabling external synchronization of feedrate override through the parameter block you can enable the feedrate override through this input Do this by setting bit 16 of word 17 in the parameter block ON Axis 1 Set bit 16 of words 36 and 55 for axis 2 and 3 respectively This allows you to activate a preloaded feedrate override value to change speed on several axes at the same instant Jog Forward In the manual mode the module accepts the signal at terminal 8 of the left wiring arm as a low true jog forward signal When the module receives this signal it moves the axis in the positive direction at the rate established through block transfer External Power Supplies Chapter 5 Hardware Description Jog Reverse In the manual mode the module accepts the signal at terminal 9 of the left wiring arm as a low true jog reverse signal When the module receives this signal it moves the axis in the negative d
139. grammed as continuous A moveset can contain a mix of single step and continuous moves 4 6 4 Positioning with Allen Bradley Figure 4 7 Moveset Profile with all Continuous Moves 1 Move2 e Move3 Rate Position 0 1 2 3 4 5 6 7 8 Move 4 11012 11012 Move Alternatives In place of a move to position in any move block you can select one of the following Dwell Instead of an endpoint and rates you can program a time in seconds in the move block When the 1771 ES expander executes a dwell move block it stops axis motion for the programmed amount of time Preset to Position You can program an axis position preset value in the command block When the 1771 ES expander executes a preset to position it sets its axis position register to the programmed preset value No axis motion occurs Move to Position with Offset The parameter block contains an offset value When the 1771 ES expander executes a move to position with offset it adds this offset value to an offset accumulator For every move it adds the value stored in the accumulator to the programmed endpoint then executes the move Constant Velocity This command clears the position register to zero before moving the axis to the position you specify By repeatedly generating continuous constant velocity moves you can cause uninterrupted motion
140. hapter 7 Formatting and Interpreting Data Blocks Figure 7 31 Moveset Block IDs Showing Allowed Moveset Sequencing Axis 4 Axis 2 Axis 3 010 011 Ros s E s 100 101 110 co y 11015 Bit 13 Escape Move If you turn on this bit the controller identifies this as an escape moveset block Follow these rules when programming an escape moveset block 1 The escape moveset must be the first moveset transferred to the 1771 M3 controller at power up or reset Consequently it must have moveset ID 001 axis 1 010 axis 2 or 011 axis 3 The next moveset pointer must point to a moveset block with ID 100 axis 1 Rate Axis 1 Rate Axis 2 Rate Axis 3 Moveset Block 1 ID 001 Chapter 7 Formatting and Interpreting Data Blocks 101 axis 2 or 110 axis 3 that is the moveset that you want to normally execute first The moveset that contains the escape move must contain no other moves The escape moveset thus contains only one move and a next moveset pointer that identifies the moveset that you want to normally execute first Figure 7 32 Moveset Profiles Showing Alternating Moveset IDs Moveset Block 2 ID 100 Moveset Block 3 ID 001 Position Moveset Block 1 Moveset Block 2 Moveset Block 3 ID 010 ID 101 ID 010 N ut Position Moveset Block 1 Moveset Block 2 Moveset Block 3 ID 110 ID 011 ID 011 N NOTE Moveset block ID i
141. he effect of the disturbances Appendix Glossary Gain The ratio of the magnitude of the output of a system with respect to that of the input Gate A device that blocks or passes a signal depending on the presence or absence of specified input signals Incremental Dimension A dimension expressed with respect to the previous position of the coordinate axis Initialize To cause a program or hardware circuit to return to an original state Instability The state or property of a system where there is an output for which there is no input Instruction A statement that specifies an operation and the values or locations of its operands Integrator A device that integrates an input signal usually with respect to time Jog A control function that provides for the momentary operation of a servo drive for manual control of axis motion Manual Feedrate Override The ability of the operator to manually change the feedrate Millisecond ms One thousandth of a second Noise An extraneous signal in an electrical circuit capable of interfering with the desired signal Open Loop A signal path with feedback Overshoot The amount that a controlled variable exceeds the desired value after a change of input Point to Point Control System A system that controls motion only to reach a given end point but exercises no path control during the transition from one end point to the next A 3 Appendix Glossary
142. he following selections Absolute or incremental positioning In an absolute move the endpoint value specifies a position coordinate relative to the current axis zero position In an incremental move the endpoint value specifies a position coordinate relative to the last programmed endpoint achieved by the axis Global or local values You enter a global final feedrate value and a global accel decel rate value These global rates apply to all moves except those for which you select to specify local rates A local rate applies only to a single move Halt or run After completing a move for which you have selected halt the 1771 ES expander will not execute the next move until it receives a begin or start command After completing a move for which you have selected run the 1771 ES expander will immediately execute the next move without waiting for a start command With halt selected the module executes a single step move With run selected you can select moves to be either single step moves or continuous moves Single step or continuous When the 1771 ES expander executes a single step move it decelerates the axis to zero velocity at the programmed endpoint When it executes a continuous move it attempts to blend the move smoothly with the final feedrate of the next move if the next move is in the same direction The moves in Figure 4 6 are all programmed as single step moves Figure 4 7 shows the same moveset with all moves pro
143. his word if you select global feedrate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 N metric inch Deceleration rate ipm sec or mpm sec meters min sec BCD format 11022 Next Moveset Pointer The final word of the moveset block contains the PC data table address of the next moveset Figure 7 39 Figure 7 39 Next Moveset Block Pointer Word Next Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 YY YO Data table address of next moveset block BCD format 11023 Chapter 7 Formatting and Interpreting Data Blocks You must include a next moveset pointer word if you turn off the end of program bit in the moveset control word When the 1771 M3 controller has transferred the last move of a moveset to the 1771 ES expander the 1771 M3 controller immediately requests transfer of the next moveset using the next moveset pointer Because the time required for status block transfer and moveset block transfer you must be sure that the last two moves of any moveset that is to be followed immediately by another moveset have sufficient execution time to allow the necessary block transfers If you allow insufficient time a momentary decrease in axis velocity or an unintended dwell may occur between continuous moves in two consecutive movesets If the delay is greater than 30ms the
144. ical in certain situations For example operator commands are transmitted to the 1771 M3 controller via command block transfer Depending on when a command is issued up to four block transfers two read two write may occur before the 1771 M3 controller can act on it Another example involves continuous execution of consecutive movesets The 1771 M3 controller stores one moveset block on board It transfers individual moves to the 1771 ES expander one at a time The 1771 ES expander stores two moves on board the current move it is executing and the next move After the 1771 M3 controller transfers the last move of a moveset to the 1771 ES expander it requests transfer of the moveset block from the PC processor This request is transmitted via the status block In the worst case four block transfers two read two write may occur before the 1771 M3 controller can send the next move to the 1772 ES expander If the 1771 ES expander completes execution of the first two moves of a moveset before it receives the next move an unintentional dwell may occur in move execution Factors involved in block transfer timing include System scan time block length system I O configuration the number of enabled block transfer instructions in a given program scan To calculate worst case block transfer times assume maximum block length 64 words write 14 words read and that a block transfer instruction is enabled for each block transfer modu
145. ider in the servo drive place a 27k ohms 1 4 Watt potentiometer between the servo drive and terminal 11 of the 1771 ES expander 4 Set the potentiometer for maximum resistance until you perform the integration procedures chapter 9 6 26 Connecting A B Encoder and Drive Chapter 6 Installing the Assembly 5 Connect the tachometer high signal to terminal 11 6 Connect the tachometer low signal to terminal 12 7 Connect the shields of the cable segments 8 Connect the shield to ground at the I O chassis end Figure 6 1 shows the jumpers in the position in which we place them for shipping the 1771 ES expander to you These channel polarity jumper settings select high true polarity These channel signal mode jumper settings select differential mode This marker logic jumper setting selects the marker to be gated with channel A and channel B If you use the Allen Bradley 845N SJDN4 C encoder leave the jumpers set to the position shown in Figure 6 1 With the jumpers set as shown in figure 1 connect the 845N SJDN 4 C encoder to the 1771 ES expander as shown in Figure 6 16 We show the channel A signal connection reversed with the not channel A connection and the channel B signal connection reversed with the not channel B connection This inversion of the channel A and B polarity allows the marker to be high at a time when both channels A and B are high Use an 8 to 15V dc power supply for the input circuits Connect the plus
146. ier is the gain break speed X 111 x 10 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 11 Axis 1 Word 30 Axis 2 Word 49 Axis 3 This BCD value 99 max times 2 Gain reduction factor is the in position band in increments of feedback resolution Rapid Traverse Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 12 Axis 1 Word 31 Axis 2 Word 50 Axis 3 tri Em E point Multiplier point 001 x 10 This BCD value 0 999 ipm 000 x 10 19 99 mmpm max times the H x 102 multiplier is the rapid traverse rate 110 x 10 111 2x 10 C 3 Appendix C Parameter Block High Jog Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 13 Axis 1 e Word 32 Axis 2 Word 51 Axis 3 E metric ae decimal Multiplier point e This BCD value 0 999 ipm or 010 x 10 19 99 mmpm max times the 100 x 10 multiplier is the high jog rate It must 110 107 not be higher than the rapid traverse 111 2x10 rate Low Jog Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 jode XE PF 18 Word 52 Axis 3 M tric decimal deci E ecimal Multiplier point point 001 x 10 000 x 10 This BCD value 0 999 ipm or 010 x 107 19 99
147. in chapter 9 Inputs Outputs The 1771 M3 controller requires no connections You will make all wiring connections to the 1771 ES expander Figure 5 1 shows the terminals on the 1771 ES expander These terminals provide the connection points for all the inputs and outputs of the servo positioning assembly Limit the cable length to 50 feet for all connections Figure 5 1 Terminals On the 1771 ES Expander Showing Input and Output Signals 5 O GJ el o lle in 1 Input Supply 5to 30V dc 15 IQ 1 Analog Supply 15V dc 2 Channel 2 INS IS 2 Not Used 3 Channel 3 O Q 3 Analog Output gt 4 Channel B 4 IN JIS 4 Analog Return 5 Channel B 5 LIS IS 5 15V DC Common gt 6 Marker 6 Q Q 6 Analog Supply 15V dc 7 Marker 7 S 7 HDW Done gt 8 Jog Forward HDW Star 8 S Q 8 Drive Disable Supply 9 Jog Reverse FDRT 9 IS 169119 Digable Output 10 Home Limit Switch 10 S S 10 Drive Disable Common v 11 Hardware Stop 11 Tachometer 12 5to 3
148. ing assembly begins execution of the next move block immediately after completing the current move block without waiting for a start or begin command If bit 17 is on continuous the moves are blended smoothly If bit 17 is reset single step the axis decelerates to zero velocity before starting the next move Halt If you turn on the run halt bit the servo positioning assembly decelerates the axis to zero velocity at the programmed endpoint then waits for a motion command before executing the next move block regardless of the setting of bit 17 single step or continuous The run halt bit applies to all move blocks including presets and dwells Figure 7 35 shows a moveset profile with examples of various bit 16 bit 17 combinations Table 7 C explains the various combinations with reference to the figure 7 52 7 Formatting and Interpreting Data Blocks Figure 7 35 Moveset Profile Showing Single step Continuous and Run Halt Combinations Refer to Table 7 C 1 Move 1 Move 2 Move 3 Move 4 Move 5 V4 V2 V5 Continuous Run Single Step Run Continuous Run Single Step RuR Distance 0 e End Pos 1 End Pos 2 End Pos 3 End Pos 4 End Pos 5 Halt End Pos 6 V6 Move 6 11019 7 53 Chapter 7 Formatting and Interpreting Data Blocks Table 7 C Single Step Continuous and Run Halt Combinations
149. into word 2 parameter block of the parameter block word 3 command block of the parameter block word 4 initial moveset block axis 1 of the parameter block word 5 initial moveset block axis 2 of the parameter block word 6 initial moveset block axis 3 of the parameter block the last word next moveset block of a moveset block First Status Word Each bit of the first status word Figure 7 4 corresponds to a particular axis condition Chapter 7 Formatting and Interpreting Data Blocks Figure 7 4 First Status Word First Status Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 1 Ak A Excess Error Loss of In Position Feedback Done Insufficient Data fL Ready Travel Limit Hardware start Travel Limit Slide Stop Feed Reduction Jog Feedrate Override Enable Hardware Stop Home Immediate Stop 1 Auto 0 Manual 11053 Bit 0 In Position The 1771 M3 controller turns on this bit when following error is less than twice the in position band value programmed in the parameter block word 11 When the in position bit is on it indicates that the axis has moved to within a specified distance of the programmed end point Bit 1 Done The 1771 M3 con
150. ion command value The difference is the following error which is amplified and converted to an analog velocity command signal This signal directs the axis to move in the right direction the position value moves closer to the position command value The following error is a function of the axis velocity divided by the positioning loop gain K1 The following error is multiplied by the gain 3 3 Chapter 3 Positioning Concepts to generate the velocity command Gain is expressed in ipm mil where 1 mil 0 001 in or mmpm mil where 1 mil 0 001 mm For example with a velocity of 100 ipm and a gain of ipm mil the following error is velocity 100 ipm 2following error gain lipm mil 100 mil When you increase the gain you decrease the following error and decrease the cycle time of the system However the gain that you can use is limited by the drive the motor and the machine a gain that is too large causes instability Feed Forward To decrease the following error without increasing the gain we can add a feed forward component Figure 3 4 Figure 3 4 Velocity Loop Positioning Loop and Feed Forwarding Velocity Command following Error K Axis Feedrate Axis Motion Encoder Feed K Forward S Motor ec 3 2 Position Following i Axis Command Error n ey Feedrat
151. ion values for the move If you turn off this bit the servo positioning assembly uses the global accel decel rate in the parameter block Note that if you select global accel decel then the move uses the single value programmed in the parameter block for both acceleration and deceleration rates For dwells and presets this bit must be off if not error code 21 appears in the status block Use of local accel and decel rates lowers the number of moves you can program in a moveset block Table 7 B You must select either the global accel decel value or a local acceleration and deceleration value for each move even though you may anticipate that the moves will execute in the continuous run mode so that some programmed accelerations and decelerations do not take place This is because the slide stop command in the command block uses the deceleration rate of the current move that is executing Bit 15 Feedrate If you turn on bit 15 you must enter a local feedrate word in the move block If you turn off this bit the move is executed at the global feedrate in the parameter block rapid traverse rate and this move block must not include a local feedrate word For dwells and presets turn off this bit or the programming error bit will go on in the status block Chapter 7 Formatting and Interpreting Data Blocks Use of local feedrates lowers the number of moves you can program in a moveset block Table 7 B Table 7 B Moveset
152. irection at the rate established through block transfer Home The module accepts the signal at terminal 10 of the left wiring arm as a low true home signal The module considers the first marker pulse after the home signal as the home position Hardware Stop The module accepts the signal at terminal 11 of the left wiring arm as a high true hardware stop signal Unless this input is pulled low the module holds the velocity command output signal at zero and disables the servo drive by turning off the drive disable circuit Encoder Inputs Terminals 2 3 4 5 6 and 7 on the left wiring arm provide connection points for input signals from the encoder Through jumpers on the module you can select each channel individually for either single ended or differential and for either high true of low true input signals If you use a single ended encoder limit the input pulse rate to 20k Hz If you use a differential encoder limit the input pulse rate to 250k Hz The 1771 ES expander is compatible with Allen Bradley Incremental Differential Line Driver Encoders cat no 845N SJDN4 C and with other encoders having current sinking 5 30V dc line driver outputs totem pole TTL outputs or open collector outputs You must provide at least two external dc power supplies to provide power for the input and output circuits 5 7 Chapter 5 Hardware Description Compatible Processors 5 8 Input Supply You must connect a 5 30V
153. is 1 Word 34 Axis 2 Word 53 Axis 3 V Most significant digit of excess following error percentage BCD format Maximum D A voltage analog output voltage BCD format For 10 0V program 000 Excess Following Error LSD D A Voltage 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 16 Axis 1 Word 35 Axis 2 Word 54 Axis 3 V YY Least significant digit of excess following error percentage BCD format Maximum D A voltage analog output voltage BCD format For 10 0V program 000 Excess following error percent should be greater than or equal to 6 The value entered here is the percent above rapid traverse following error at which Emergency Stop is to occur 11043 7 31 Chapter 7 Formatting and Interpreting Data Blocks 7 32 Feedrate Reduction When axis following error reaches 106 25 of rapid traverse following error the servo positioning assembly automatically reduces feedrate by 50 of the feedrate value This feedrate reduction provides an opportunity for following error to decrease Feedrate returns to the programmed value when following error is reduced to less than or equal to 106 2596 of rapid traverse following error and the current move is completed Note that if the excess following error value you enter is less than or equal to 6 the axis e
154. is is moving in the positive direction it stops at the programmed endpoint without overshoot Ifthe axis is moving in the negative direction it overshoots the endpoint by 0 001 inch then returns to the programmed endpoint Backlash takeup affects only halt moves that command the axis to stop at a move endpoint For blended moves backlash takeup has no effect Also backlash takeup is active only in auto mode Backlash takeup has no effect on axis motion in the manual mode This parameter has a 4 digit BCD value in the range of 0 0001 to 0 7999 inches or 0 001 to 7 999 mm Offset Word 24 43 62 specifies the value the servo positioning assembly adds to the offset accumulator when the servo positioning assembly executes one of the following 7 37 Chapter 7 Formatting and Interpreting Data Blocks 7 38 position with offset move in a moveset an offset command from the command block This parameter has a 4 digit BCD value that can be in the range 0 0001 to 0 7999 inches or 0 001 to 7 999 mm Figure 7 27 Figure 7 27 Offset Word Offset Word 24 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 43 Axis 2 Word 62 Axis 3 inch metric decimal decimal Sian pent point Offset value inches or 0 9 4 millimeters BCD format 1 11049 Tachometer Conversion Factor The servo positioning assembly uses bits 00 thru 03 of word 25
155. issue the begin command after the escape move is complete the servo positioning assembly executes the first move of the normally executed moveset that follows the escape moveset That is the moveset specified by the next moveset pointer of the escape moveset Bit 2 Preset In the manual mode turn on bit 2 to generate a preset command The axis must be stopped for this command to be executed If a get new preset value command second control word has been previously executed the servo positioning assembly sets its current position value to the current preset position values for the axis in the command block If no get new preset value command has been executed since power up or reset the servo positioning assembly sets its current axis position value to zero In addition execution of a preset command clears the axis offset accumulator setting its value to zero The servo positioning assembly does not request write block transfer of the preset words of the command block unless you issue a get new preset value command Otherwise only the first and second control words for each axis are transferred in the command block Furthermore when you include the preset words in the command block in response to a get new preset value command only the axis requesting the new preset value recognizes its new values Chapter 7 Formatting and Interpreting Data Blocks Bit 3 EOM Stop In the auto mode turn on bit 3 to generate an end of move
156. issue the search home command the servo positioning assembly moves the axis in the direction you specify by bit 7 of the second control word for the axis search home direction and at the speed specified by bit 14 of the second motion control word jog speed select high or low The axis keeps moving until it activates the home limit switch When the axis trips the home limit switch it decelerates to zero then proceeds at the low jog rate to the position at which the first encoder marker occurs If the axis cannot decelerate to zero velocity at the first marker location it decelerates past it stops then returns to the marker location This marker location is the axis home position When the axis reaches its home position the servo positioning assembly assigns the value in the home position words of the parameter block as the current position For a firmware revision F or earlier 1771 ES expander at power up the axis must be positioned at least one encoder revolution away from the home limit switch transition before you issue a search home command so that a marker can be found before the switch transition Otherwise the switch transition will cause a slide stop without establishing a home position For a firmware revision G 1771 ES expander if you issue a search home command while the home limit switch is closed the axis first moves away from the home limit switch until the switch has opened and the first market has been found or one e
157. l excess following detection loss of feedback detection software travel limits backlash takeup offset preset Chapter 2 Introducing the Servo Positioning Assembl Benefit precise closed loop positioning programming flexibility precise positioning at low speed with stability at high speed optimize the machine cycle time over varying loads flexible positioning accuracy flexible manual positioning precise dwell times automatic drive shutdown if the axis following error becomes too large allow automatic drive shutdown during a move if tachometer or encoder feedback is lost guards against axis overtravel compensates for mechanical backlash compensates for a variation in tool length or fixture dimension easy redefinition of axis coordinates 2 5 Chapter 2 Introducing the Servo Positioning Assemb 2 6 Feature optically isolated analog output external hardware start encoder input selectable for high true or low truel synchronized start of feedrate overridel sensing of customer power supply lossl feed forwarding constant velocity moveset overridel diagnostic words in the status blockl l for Benefit guards against noise entering the backplane circuits and limits the potential for damage due to improper connection synchronizes moves with other axes compatibility with a wider range of encoders activates a pre lo
158. l word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Wordi 0 1 0 0 0 0 0 0 A Identifies this as No of Axes a parameter block 0 0 1 1 0 1 1 2 0 Inch 1 1 123 1 Metric Parameter Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 p cma Hc Data table address of parameter block BCD format Word 2 Command Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 g M Data table address of command block BCD format Axis 1 Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Data table address of first moveset block to be transferred for axis 1 BCD format Axis 2 Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 FO J Data table address of first moveset block to be transferred for axis 2 BCD format Axis 3 Moveset Block Pointer 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 3 Word 4 Word 5 Word 6 Data table address of first moveset block to be transferred for axis 3 BCD format Feedback Resolution 17 16 15 14 13 12
159. le in the system in every program scan The following sections describe calculation of worst case block transfer times for PLC 2 30 remote and local systems and for the Mini PLC 2 15 system PLC 2 30 Remote System To find the time between block transfers for a given module in a PLC 2 30 remote system perform the following steps Chapter 8 Find the block transfer times of each block transfer module in the system Determine the sequence of block transfers for the system Sum block transfer times according to the system sequence Block Transfer Time System scan time for a PLC 2 30 remote system is the sum of processor program scan time processor I O scan time and remote I O scan time For worst case calculation assume that the Remote I O Scanner cat no 1771 SD2 can process only one block transfer operation per remote I O scan To calculate worst case block transfer time for a module perform the following steps Write down known facts program length number of chassis number of block transfer modules block lengths W Calculate system values determined by system configuration program scan time in ms PS 5ms K word x program length processor I O scan time in ms PIO 0 5ms chassis x number of chassis remote I O scan time in ms RIO 7ms chassis x number of chassis Calculate individual block transfer times write transfer time in ms TW PS PIO 2 RIO 0 5W 13 read transfe
160. les When the system is powered up the three servo controller indicators all flash on then off If the processor is in the run mode with no fault the active indicator comes back on If the processor is in the program or test mode with no fault the indicators all turn off and stay off until the processor is taken out of the test or program mode Monitoring 1771 ES Expander Indicators Chapter 10 Troubleshooting The 1771 ES expander module has six indicators Figure 10 2 Module active This green indicator is on when the 1771 ES expander is Operating normally Marker This green indicator is on when the 1771 ES expander detects the encoder marker signal Note that this indicator turns on only if the signal from encoder channels A and B are true when the marker signal is true unless you set the marker logic jumper for ungated Home This green indicator is on when the axis is at the home position Tachometer calibrate TACH CAL This green indicator is used in setting up the loss of feedback detection feature see section titled Tachometer Calibration chapter 9 Hardware stop HDW STOP This red indicator goes on when the hardware stop input is on It stays on until the 1771 ES expander is reset Diagnostic DIAG This red indicator goes on when the 1771 ES expander detects a module fault At power up the module active marker home hardware stop and diagnostic indicators all flash on then
161. lish a home position somewhere along the slide travel For example we can place a limit switch near the end of the slide travel The first market pulse after the limit switch is activated could then designate the home position Figure 3 8 Summary Chapter 3 Positioning Concepts Figure 3 8 Marker Pulse Establishing a Home Position Limit Switch Marker Pulse Axis Motion __ gt Home Position 12004 Once we establish a home position we can use it as an absolute reference point for all moves In this chapter we described concepts of closed loop positioning Now you are ready for concepts of position with an Allen Bradley PC This material is covered in chapter 4 3 11 Chapter Objectives Where the Servo Positioning Assembly Fits In Positioning With an Allen Bradley Programmable Controller The previous chapter described concepts of closed loop positioning This chapter describes where the servo positioning assembly fits into a positioning system and how the servo positioning assembly communicates with the PC processor Figure 4 1 shows where the servo positioning assembly and a servo drive fit in the positioning system we described in the previous chapter The servo drive contains the velocity loop summing point and amplifier The servo positioning assembly contains the positioning loop summing point and the feed forward summing point The servo positioning assembly sends
162. lock ID of the moveset block currently being executed unless the diagnostic valid bit bit 6 is on When the programming error bit is on bits 10 thru 12 indicate the block in which the error was detected Bits ot 10 Block 000 Parameter 001 Axis 1 Odd Moveset 010 Axis 2 Odd Moveset 011 Axis 3 Odd Moveset 100 Axis 1 Even Moveset 101 Axis 2 Even Moveset 110 Axis 3 Even Moveset 111 Command Bit 13 Axis Fault The 1771 M3 controller turns on this bit when communication between it and the 1771 ES expander is lost Bit 14 Following Error Valid This bit is on if the next two status block words for this axis contain axis following error Bit 15 Position Valid This bit is on if the next two status block words for this axis contain axis position If the axis position value exceeds the maximum allowable value 999 9999 in or 19999 999 mm the servo positioning assembly turns off both the position valid and following error valid bits bits 15 and 14 and sets the position value in the status block at the maximum value Chapter 7 Formatting and Interpreting Data Blocks Bit 16 Diagnostic Valid When you turn on the select diagnostic bit of axis control word 2 of the command block this bit goes on to indicate that the position or following error words in the status block contain diagnostic information Bit 17 Command Taken When you turn on the new parameter moveset override offset preset or get new pres
163. lots Install it in a pair of slots that make up an I O module group Through switches and jumpers on the 1771 ES expander you can select various aspects of the module s operation To access these switches and jumpers lay the 1771 ES expander on its right side and remove the left cover Locate the switches and jumpers through Figure 6 1 Figure 6 1 1771 ES Expander Switches and Jumpers Riser te Input Resistance WILC Assembly DM T Lr Switch Assembly High True gt Low True CH A Polarity Jumper CH B Polarity Jumper amp Marker Polarity Jumper CH A Signal Mode Jumper e CH B Signal Mode Jumper e Marker Signal Mode Jumper e Single Ended Differential on Not Gated Marker Gated with CH A and CH B 12013 6 3 Chapter 6 Installing the Assembly This publication shows and describes switches as being on or off Printed on the actual switch assemblies are the words ON and OFF or the word OPEN OPEN corresponds to OFF Use a blunt pointed instrument such as a ball point pen to set these switches Never use a pencil graphite could jam the switch Figure 6 2 shows details of a jumper connecting two pins Each jumper connects two of a set of three pins To change a jumper setting follow these steps 1 Pull the jumper straight up 2 Position the jumper over the pins y
164. lt indicators turn on Expander communication fault EXPANDER COMM FAULT This red indicator is normally off It turns on to indicates a communication fault controller between the 1771 ES and the 1771 ES expander If a hardware fault is detected at power up both the processor communication fault and expander communication fault indicators turn on Active This green indicator is normally on It turns off to indicate a hardware fault on a 1771 ES expander The active indicator blinks to indicate one of the following improper module configurations The I O chassis contains 1771 ES expander The I O chassis contains two 1771 ES expanders with the same switch settings for axis identification The I O chassis contains a 1771 ES expander with switches set for axis 2 but no 1771 ES expander for axis 1 If the I O chassis contains only one 1771 ES expander it must be set for axis 1 The I O chassis contains a 1771 ES expander with switches set for axis 3 but no 1771 ES expander for axis 2 The I O chassis contains more than one 1771 M3 controller The I O chassis contains another master slave module combination in addition to the servo positioning assembly Master slave combinations include the Analog Input Module cat no 1771 IF the Analog Output Module cat no 1771 OF the Stepper Controller Module cat no 1771 M1 and the Thermocouple Input Module cat no 1771 IX and their respective slave modu
165. ltage Since analog output voltage is directly proportional to axis speed you can use the vertical axis to represent either variable If gain is relatively high following error will be relatively small because the system will be more sensitive to changes in following error If gain is 7 23 Chapter 7 Formatting and Interpreting Data Blocks low following error becomes relatively larger because the system is not as responsive to changes in following error Choose a gain value to match the capability of your axis drives motors and mechanics and provide adequate system response Figure 7 14 Following Error Vs Speed for Various Gains Analog Output Voltage Axis Speed High Gain Low Gain Following Error High Gain Low Gain Low Following Error High Following Error 11036 Parameter block values for gain and in position band must provide a stable system and maintain desired positioning accuracy If gain is too high the axis may overshoot programmed endpoints and oscillate or hunt about them If gain is too low the axis may stop before it is within the desired in position band You can increase in position band but this decreases positioning accuracy Use bit 15 of this word to select the encoder lines multiplier This encoder lines multiplier you select times the encoder lines value you select in the previous word must match the number of lines per revolution of the encoder Chapter 7 Form
166. ly Override Enable Readout Select 1 Software Travel 0 0 Position Limits Override 1 0 Following Error p 0 1 Diagnostic 1 Return to Position 1 1 Diagnostic 11028 Manual Mode Only Bits 0 thru 6 Axis Feedrate Override Enter the axis feedrate override value into bits 0 6 This specifies the percentage of the programmed feedrate at which moves will be executed if feedrate override is enabled The value can range from 0 through 127 expressed in binary form Two bits must be on for axis feedrate override to affect enabled moves in auto mode bit 7 of the SMCW feedrate override enable for current move only bit 10 of the axis control word 2 axis feedrate override enable In manual mode only bit 10 of axis control word 2 must be on to enable feedrate override for all manual mode axis motion Note that feedrate override affects only the feedrate value for a move not accel decel values For axis motion to occur the feedrate override value must be greater than zero or the axis feedrate override enable bit must be off to disable the feedrate override function You can select the moves to be affected by the feedrate override value by turning on bit 7 of the SMCW If this bit is off feedrate override does not affect the move If you turn on bit 16 of the most significant home position word see section titled External Synchronization of Feedrate Override feedrate 7 73 Chapter 7 Formatting and In
167. mation about fault conditions detected by the servo positioning assembly can be block transferred to the PC processor At the PC processor you can use the ladder diagram program to respond to diagnostic information about fault conditions in any way you feel is appropriate for your application This may include turning off machinery turning on alarms or generating report printouts Furthermore with an Allen Bradley Data Highway network you can send this diagnostic information to a computer or other Allen Bradley PC processors The servo positioning assembly provides specific fault responses if certain critical connections are broken Loss of Feedback The 1771 ES expander continuously monitors the tachometer and encoder feedback If it senses an imbalance between these signals it holds the velocity command output signal at zero and disables the servo drive through the drive disable circuit Therefore if the cable from either the encoder or the tachometer breaks the 1771 ES expander will disable the servo drive Hardware Stop You must connect a set of normally open contacts of your master control relay between the hardware stop input terminal and the input power supply common terminal Normally the master control relay would be energized pulling the hardware stop input low This allows the module to enable the servo drive However if the master control relay de energizes for any reason such as extreme overtravel limit or emergenc
168. mory 2 Block Transfer a transfer of data from the processor data table to an intelligent I O module Status Block Status Block Format Future Use Address Pointer Status Word 1 Axis 1 Status Word 2 Axis 1 MS Position FE Diagnostic Axis 1 LS Position FE Diagnostic Axis 1 Status Word 1 Axis 2 Status Word 2 Axis 2 MS Position FE Diagnostic Axis 2 LS Position FE Diagnostic Axis 2 Status Word 1 Axis 3 Status Word 2 Axis 3 MS Position FE Diagnostic Axis 3 LS Position FE Diagnostic Axis 3 Address Pointer Word 2 The module sends diagnostic information in this word when you request it thru the command block or when the module detects an error in the parameter block immediately after power up 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 aS E I U Address of next block to be write transferred to the 1771 M3 controller BCD format B 1 Appendix Status Block First Status Word Word 3 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 08 02 01 00 Word 7 Axis 2 Word 11 Axis a Excess Error Loss of Feedback Insufficient Data Travel Limit Travel Limit Feed Reduction Hardware Stop ie In Position Done Ready Jog Hardware Start Stop Jog Feedrate Override Enabl
169. n on bit 11 to generate an offset command When on this bit commands the servo positioning assembly to add the offset increment value in the parameter block to an offset accumulator The offset accumulator value is added to each programmed endpoint during move execution The command taken bit in the status block remains on as long Chapter 7 Formatting and Interpreting Data Blocks as this offset bit is on A preset initialize home or reset command clears the offset accumulator Important An offset command has no effect on the two moves already stored on board the 1771 ES expander module Only moves sent to the 1771 ES expander after you issue the offset command are affected The offset command can be executed only when the servo positioning assembly is in the manual mode When the servo positioning assembly is in auto mode use a move to position with offset move block instead of the offset command to increment the offset accumulator Bit 12 New Parameter In the manual mode turn on bit 12 to generate a new parameter command This command is typically used to indicate that the parameter block has been changed and the 1771 M3 controller should request it again through the status block The servo positioning assembly must be in the manual mode and the axes stopped for this command to be acknowledged by turning on the command taken bit If you issue the command while an axis is in motion the status block indicates a programming erro
170. n the command block However you change the feedrate for a particular move only if you had enabled feedrate override in the move block With the bit on you must still enable feedrate override in the command block and move block before feedrate changes However the 1771 ES expander will not change the feedrate until you close the feedrate override enable input This allows you to synchronize the feedrate override of several axes Global Accel Decel Rate Word 19 38 57 specifies the acceleration and deceleration rate the servo positioning assembly uses for all jogs and for moves in movesets for which you do not enter local acceleration and deceleration rates It is also the deceleration value used when executing a slide stop during manual mode operation of an axis or when you issue a reset command during axis motion Figure 7 23 Figure 7 23 Global Accel Decel Rate Word Global Accel Decel Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 19 Axis 1 is Word 38 Axis 2 Word 57 Axis 3 B N inch metric decimal decimal oint point p BCD global accel dec rate 9999 ipm s or 99 99 mpm s max dias Decel Step Rate Word 20 39 58 specifies the deceleration step rate Figure 7 24 This parameter applies to deceleration of axis motion when the servo positioning assembly is in the manual mode At axis feed rates equal to or less than that specified by this
171. n to provide either single step moves or continuous moves Each move requires a minimum of three words a single move control word and two words to define position or dwell time and can include three optional words a rate word an accel word and a decel word for a total of six A moveset control word applies to the entire block If additional moveset blocks are needed you also need a next moveset point word A moveset block can be 64 words long maximum and describe 21 moves maximum To describe 21 moves in a single moveset block all 21 7 3 Chapter 7 Formatting and Interpreting Data Blocks Status Block 7 4 moves would have to use the global accel decel and final rate values from the parameter block Upon request from the status block the PC processor sends a moveset block to the 1771 M3 controller which transfers each move description to the 1771 ES expander one at a time The 1771 ES expander generates the analog voltage to command axis motion as programmed Command Block The command block for a 1 axis system has up to four words a 2 axis system has up to eight words a 3 axis system has up to 12 words This block regularly transfers from the data table to provide commands such as start slide stop search home jog reset and offset for each axis unless the 1771 M3 controller needs a parameter or moveset block You must include the command block address in the parameter block Data Table Allocation You must all
172. n with next Move Commands 11026 7 62 Chapter 7 Formatting and Interpreting Data Blocks Bit 0 Jog In the manual mode turn on bit 0 to generate a jog plus command The axis jogs in the positive direction as long as this bit is on unless the axis reaches the software travel limit Jog speed is either high or low as determined by bit 14 of the second control word for the axis You specify high and low jog speed values in the parameter block The axis accelerates to jog speed and decelerates from it at the rate you specified in the parameter block If you use the decel step velocity parameter block it applies to deceleration from jog rates Bit 1 Start In the auto mode turn on bit 1 to generate a start command When you turn on this bit the servo positioning assembly continues moveset execution starting at the point it was last stopped by completion of a halt move EOM stop or slide stop The start command can also be used to start moveset execution after an escape move is executed This command can start moveset execution at the beginning of the cycle or after the interruption of the moveset The 1771 M3 controller only recognizes a start command when the axis is in position Also refer to the begin command bit 2 Bit 1 Jog In the manual mode turn on bit to generate a jog minus command The axis jogs in the negative direction as long as this bit is on unless the axis reaches the software tra
173. nce you have completed the axis integration procedures never turn this bit off Without loss of feedback detection if encoder or tachometer feedback is lost unexpected axis motion can occur resulting in damage to equipment and or injury to personnel Turn on the tachometer calibrate bit bit 16 of axis control word 2 in the command block Set the tach fine potentiometer on the 1771 ES expander to its fully clockwise position Set the tach coarse potentiometer to its fully clockwise position Figure 9 3 Chapter 9 Integrating Axes Jog the axis in either direction at maximum speed rapid traverse rate with 127 feedrate override If you don t have enough axis travel in which to adjust the potentiometer disconnect the servo motor from the leadscrew as in the open loop procedure see section titled Open loop Procedure in this chapter Set the potentiometer see section titled Connecting the Tachometer in chapter 6 for a 50V maximum tachometer signal at the 1771 ES expander If the tachometer voltage is less than 10V enter a conversion factor in the last word of the parameter block The conversion factor multiplied by the full scale velocity command voltage must be a value less than the tachometer voltage Figure 9 3 1771 ES Expander Test Points and Potentiometers U White Tach Coarse Tach Fine o OOOOOOOOO L Yellow 11066 With power
174. ncoder revolution has been completed Once this occurs the 1771 ES expander decelerates the axis to zero then if the marker was found it executes the search home command by moving the axis toward the limit switch to establish home position However at power up if the home limit switch is open position the axis at least one encoder revolution away from the home limit switch before issuing a search home command so that a marker can be found before the switch transition If while executing a search home command the axis encounters a software travel limit before it reaches the home limit switch the servo positioning assembly 7 67 Chapter 7 Formatting and Interpreting Data Blocks 7 68 commands a slide stop turns on the appropriate travel limit bit and the slide stop bit in the status block sets the current position value to zero You can then issue another search home command You must perform a search home operation after system power up to initialize the axis position scale Also be sure that the home limit switch is in the direction the axis moves when you issue the search home command as you specify in the parameter block Bit 4 Escape In the auto mode turn on bit 4 to generate an escape command This command causes the servo positioning assembly to stop executing the current move and execute the escape move stored on the 1771 ES expander If the escape move endpoint is in the direction of current axis
175. nd current position word values should begin increasing As the axis crosses the zero position while moving in the negative direction the sign bit bit 17 of the most significant axis position word in the status block should change from off positive to on negative and the current position word values should begin increasing If you obtain opposite results interchange the channel A connections with the channel B encoder connections at the left wiring arm of the 1771 ES expander module Repeat steps 20 21 and 22 to ensure that you have corrected the problem This completes the open loop drive procedure Repeat this procedure for all axes being integrated Follow the procedure presented in this section to close the axis positioning loop You must perform this procedure in conjunction with the servo drive manufacturer s instructions This procedure is not independent of the open loop integration procedure You must perform the open loop drive procedure before you can perform the closed loop procedure The following steps are the closed loop integration procedure 1 2 Turn off the axis power and remove drive fuses Disconnect the battery box from the analog output and analog return leads Connect the analog output lead to terminal 3 of the right module wiring arm Connect the analog return lead to terminal 4 10 Chapter 9 Integrating Axes Disconnect the switch from the drive disable terminal and lead Reco
176. next move will not execute until you issue a motion command The insufficient data bit will be on in this condition Important The moveset block specified by the next moveset pointer must have an allowable block ID 7 59 Chapter 7 Formatting and Interpreting Data Blocks Command Block During normal operation the command block is repeatedly transferred to the 1771 M3 controller Unless the 1771 M3 controller requests a moveset block or the parameter block it requests the command block Figure 7 40 Command block size depends on whether there are one two or three axes For each axis the command block contains two control words It may also include two position preset words depending on whether a position preset is programmed The following sections describe the command block words Figure 7 40 Command Block Showing Word Assignments a Single Axis c Three Axis Word Word 1 Control Word 1 1 Control Word 1 Axis 1 2 Control Word 2 2 Control Word 2 Axis 1 3 Position Preset MS Word 3 Control Word 1 Axis 2 4 Position Preset LS Word 4 Control Word 2 Axis 2 5 Control Word 1 Axis 3 6 Control Word 2 Axis 3 7 Position Preset MS Word Axis 1 b Two Axis 8 Position Preset LS WOrd Axis 1 Word Control Word 1 Axis 1 9 Position Preset MS Word Axis 2 2 E Font Word cd 10 Position Preset LS Word Axis 2 3 Control Word 1 Axis 2
177. ng steps 1 Write down known facts Program Length 4K words Number of Chassis 4 Block Length 64 words write 6 words read 3 Chapter 8 Calculate system values Program Scan Time PS 5ms K word 4 K words 20ms Processor I O Scan Time PIO 0 5ms chassis 4 chassis 2ms Remote I O Scan Time RIO 7ms chassis 4 chassis 28ms Calculate Block Transfer Times Write TW PS PIO 2 RIO 5 W 13ms 20 2 2 28 5 64 13ms 123ms Read TR PS PIO 2 RIO 5 W 4ms 20 2 2 28 5 6 4ms 87ms These times apply to all four 1771 M3 controller modules If the system included other block transfer modules separate calculations would be required for each 8 9 Chapter 8 Figure 8 4 PLC 2 30 Remote System Example 8 10
178. nitor Project Name Sample Program 2 Axis Page 3 of 6 Designers Address 509 to 531 Date 2 22 83 AxisNo_1_____ Block DescriptionMOVE SET 2 Data Table Addresg Position File Data Data Table Address Position File Data 0500 8 28 Chapter 8 Figure 8 15 Data Table Form Eample for 2 Exis Program continued ALLEN BRADLEY Programmable Controller february 1983 Hexadecimal Data Monitor Project Name Sample Program 2 Axis Page 4 _of_o_ Designer Address 6000 642 Date_2 22 83 AxsNo l BlockDescripiondove Set 3 1 oli ol uscw Move 1 Move 2 Move 3 Move 4 Move 5 Move rl a 0637 8 clilolo 8 29 Chapter 8 Figure 8 15 Data Table Form Eample for 2 Exis Program continued ALLEN BRADLEY Programmable Controller february 1983 Hexadecimal Data Monitor Project Name Sample Program 2 Axis __ 5 of 6 Designer Address 700 to 7 27 Date 2 22 83 AxisNo 1 BlockDescripionMove Set 1 Data Table Address Position File Data Data Table Address Position File Data 133 34 35 36 8 30 1016 A Page 6 of 6 Address 000_ to eo Lond lt o Data Table Address Position 01000 1 0 2 0 3 MSCW 33 UMEN he La n ram 2 Axi 1 e ALLEN BRADLEY Programmable Controller f
179. nnect the drive disable lead to the drive disable terminal on the right module wiring arm terminal 9 or 10 depending on type of circuit WARNING To guard against injury to personnel and damage to equipment the loop contactor relay must remove the servo motor power when an emergency stop or overtravel limit switch opens Refer to chapter 6 for information about power distribution Ensure that extreme overtravel limit switches are connected in series with the loop contactor relay chapter 6 Re apply servo drive and servo positioning assembly power Verify that there is no axis motion If necessary adjust drive balance at the servo drive so axis following error is zero and no axis motion occurs when the 1771 ES expander is not commanding axis motion analog output voltage is zero volts Turn on bit 15 select readout in the second control word for the axis so the status block provides following error information Jog the axis at a speed below the gain break point Record the following error Calculate to see if the following error equals the feed rate divided by the initial gain If it does not adjust either the gain of the servo drive or the initial gain and the rapid traverse rate to achieve the proper performance Jog the axis in the positive direction at about 1 2 rapid traverse speed and note following error Record the following error Jog the axis in the negative direction at the same rate used for step 9 Again record
180. nt per revolution encoder lines number of lines per revolution feedback multiplier selected as x 1 x2 or x4 3 8 Chapter 3 Positioning Concepts The following equation shows how these factors determine feedback resolution leadscrew pitch feedback resolution encoder lines feedback multiplier You must select the leadscrew pitch encoder lines and feedback multiplier to provide desired feedback resolution and meet other requirements of your application The programming resolution of the servo positioning system is 0 0001 inch or 0 001 millimeter If you select a feedback resolution coarser than that round off your position commands so that the effective programming resolution is no finer than the feedback resolution you chose If you select a feedback resolution finer than the programming resolution positioning can be smoother However the maximum axis speed is directly proportional to the feedback resolution There is always a trade off between feedback resolution and maximum axis speed The maximum encoder input frequency for the servo positioning assembly is 250kHz Therefore to avoid a programming error you must limit the axis speed to conform to this formula programmed 1 5 x 107 axis speed lt 1 28 x feedback res x feedback mult The 1 28 factor allows for a 127 feedrate override value Each encoder line represents a fraction of a revolution of the leadscrew For example consider a 250 line enco
181. o generate a move to position The axis will move to the position specified by the sum of the value in the position words and the value in the offset accumulator register Bits 11 10 06 Set to 001 Constant Velocity Turn bit 11 off bit 10 off and bit 6 on to generate a constant velocity move This command clears the position register to zero before moving the axis to a position specified by the value in the position words By repeatedly generating continuous constant velocity moves you can cause uninterrupted motion that you could apply to conveyors winders coilers and spindle type controls Bits 11 10 06 Set to 010 Move to Position with Offset Turn bit 11 off bit 10 on and bit 06 off to generate a move to position with offset This command first adds the offset value in the parameter block to the offset accumulator register Then the axis moves to the position specified by the sum of the value in the position words and the value in the offset accumulator register The endpoints of all following moves are also modified by the offset value which remains in the offset accumulator If you execute the moveset again the offset accumulator value increments again when the move to position with offset command executes Figure 7 34 shows the effect of position with offset Rate Chapter 7 Formatting and Interpreting Data Blocks Figure 7 34 Moveset Profile Showing Position with Offset Move 1 Move
182. ocate a sufficiently large data table area for the data blocks needed in the block transfer communication Furthermore the parameter block must start at least 63 words before the end of a contiguous data table area Also each moveset block regardless of size must start at least 64 words before the end of a contiguous data table area Fora PLC 2 family processor assign data block addresses of 200 or greater to avoid processor work areas The status block which is the only block transferred from the 1771 M3 controller to the processor contains information about axis and servo positioning assembly status The first block transfer after power up writes a 6 word status block into the data table After that the status block consists of word assignments Figure 7 2 Size of Number of Axes Status Block 1 6 words 2 10 words 3 14 words Chapter 7 Formatting and Interpreting Data Blocks Figure 7 2 Status Block Showing Word Assignments Status Block Format Address Pointer Status Word 1 Axis 1 Status Word 2 Axis 1 MS Position FE Diagnostic Axis 1 LS Position FE Diagnostic Axis 1 Status Word 1 Axis 2 Status Word 2 Axis 2 The module sends diagnostic information in this word when you MS Position FE Diagnostic Axis 2 request it thru the command block or p gt when the module detects an error in LS Position FE Diagnostic Axis 2 the parameter block immediately after power up Status Word 1 Axis
183. of troubleshooting should become easier for you Glossary Absolute Dimension A dimension expressed with respect to the initial Zero point of a coordinate axis Accumulator Register A register that accumulates the axis feed increments to indicate the current commanded position for the axis to follow Adapter Module A module that provides communication between an I O chassis and the PC processor It transmits I O chassis input information to and receives output information from the processor Amplifier A signal gain device whose output is a function of its input Analog An expression of values that can vary continuously between specified limits Axis A principal direction along which a movement of the tool or workpiece occurs Backlash A relative movement between interacting mechanical parts resulting from looseness Binary A base 2 numbering system Binary Coded Decimal BCD A numbering system used to express individual decimal digits 0 thru 9 in four bit binary notation Bit Binary digit The smallest unit of information Represented by the digits 0 and 1 The smallest division of a PC word Block A set of words handled as a unit Clear To erase the contents of a storage device by replacing the contents with zeros 1 Appendix Glossary 2 Closed Loop A signal path in which results are fed back for comparison with desired values to regulate system behavior
184. off They stay off while the module performs power up diagnostics If diagnostics detect no problem the active indicator turns on Figure 10 2 1771 ES Expander Indicators SERVO SERVO ENCODER ENCODER EXPANDER EXPANDER Module Active Green Marker Green Home Green Tach Calibration Green Hardware Stop Red Diagnostic Red an are eooeooooe 10 3 Chapter 10 Troubleshooting Monitoring the Status Block The 3rd and 4th status words for an axis provide either current axis position following error or diagnostic information You can select which status to display by controlling the state of bits 11 and 15 of the axis control word 2 of the command block Turn off bits 11 and 15 to display the current axis position as shown in Figure 10 3 The maximum value is 999 9999 inch or 19999 99 mm If the axis exceeds the maximum it displays the maximum and the position valid bit goes off Turn off bit 11 and turn on bit 15 to display the following error as shown in Figure 10 3 The maximum value is 999 9999 inch or 19999 99 mm If the axis exceeds the maximum it displays the maximum Figure 10 3 Position Following Error Diagnostic Words with Position or Following error Selected Most Significant P
185. om the block pointers you enter into the parameter block or the moveset block The high byte bits 10 thru 17 of the first diagnostic word is the word pointer The word pointer is a BCD number 1 thru 64 that indicates which word is in error within the block Chapter 10 Troubleshooting The low byte bits 00 thru 7 or the first diagnostic word is the error code The error code is a BCD number that references the errors listed in Table 10 A Use the block pointer and word pointer to identify the location of the problem Then use the error code to determine the nature of the problem Table 10 A Diagnostic Code Definitions Invalid block identifier Non BCD number entered 03 Invalid bit setting unused bits must be zero 04 MS metric only bit set in inch format 05 Overflow Converted data is too large for internal registers 06 Can only change feedback multiplier from a power up reset 07 Invalid axes used programmed 08 Invalid write block address pointer 09 Invalid feedback resolution lt 0 00001 in or 0 0001 mm Invalid feedback multiplier bit setting 7 _ 3 27 i Escape move block can only have 1 move declared Invalid escape move block only moveset blocks identified in the parameter block can be escape move blocks Cannot program a preset or dwell as an escape move A valid next moveset pointer could not be found Invalid dwell time must be gt 20ms 10 6
186. onnel clear of the axis In addition have a competent person standing by to press an emergency stop switch if necessary 10 Jog the axis or execute a programmed moveset at low axis speed While the axis is moving disconnect one of the encoder leads terminals 1 thru 7 on the left 1771 ES expander wiring arm Axis motion should stop The status block should indicate both immediate stop and loss of feedback For single ended encoders loss of feedback is not detected if the channel A channel B or MARKER return connection is broken since these 3 connections are common That is all three leads must be disconnected for loss of feedback to be detected For these encoders loss of feedback is detected only when the channel A channel B or marker signal is disconnected 11 Reconnect the encoder leads and reset the system After you have performed all integration procedures for all axes test execution of your intended move profile For these tests do not install tooling or workpieces Use feedrate override at a low value so that you can more easily stop axis motion if necessary When profile execution is verified gradually increase axis speed over successive runs until you are satisfied with profile execution at full speed If you have problems with the servo positioning assembly during or after axis integration refer to chapter 10 for troubleshooting information 9 11 Chapter Objectives Monitoring 1771 M3 Controller Indicators
187. onship 3 8 Command block 7 4 7 60 Compatible Processors 5 8 connection 6 18 constant velocity 4 7 continuous moves 4 6 4 10 D Data blocks 7 1 Data Table allocation 7 4 Decel step rate 7 34 Diagnostic code definitions 7 16 10 6 Done 7 7 Drive disable output 5 12 Index Drive disable Supply 5 8 E Encoder Feedback 3 7 Encoder Input Polarity 6 6 Encoder Input Signal Mode 6 7 Encoder inputs 5 7 Encoder Lines 7 22 Excess Following error 7 31 External Power Supply 5 12 F Fault Responses 5 9 Features 2 4 Feed forward concept 3 4 Feedback Resolution 3 8 Feedrate override enable input 5 6 Feedrate reduction 7 32 Following error 3 3 Function 2 2 G Gain 3 3 Gain break speed 7 25 Gain reduction factor 7 26 Global accel decel rate 7 34 global values 4 6 H halt moves 4 6 4 8 Hardware connection Sart 6 18 Hardware done output 5 4 Hardware Start Input _5 6 Hardware stop connections 6 13 Hardware Stop Input 5 9 hardware stop input 5 7 Home limit switch input 5 7 Home limit switch connection 6 16 Index Home Position Value 7 32 scan 4 2 Illegal Combinations 7 77 In position _7 7 In position band _7 27 in position band 4 8 incremental positioning 4 11 Indicators 5 1 10 1 Initial gain 7 23 inposition 4 8 Input Supply 5 8 Input supply connections 6 12 Integrating Axes 9 1 iscrete Inputs 5 5 J Jog forward conne
188. ontrol bits in accordance with the various steps required to execute the read or write operation The execution time required to complete a read write block transfer depends on factors that include the number of Words of user program active I O channels on the scanner I O chassis entries on the I O chassis scanning sequence list for the channel Chapter 8 O channels on the scanner that contain block transfer modules block transfer modules on the channel if the I O chassis containing a block transfer module appears more than once in the I O chassis scanning sequence list count the module once each time the chassis appears in the list Typical time required for the module to complete a read write bidirectional block transfer depends on the program scan and the I O scan as follows time read write program scan 2 I O scan Program Scan The program scan is approximately 2 5ms per 1K words of user program when using examine on off and block instructions I O Scan The time required for the scanner to complete a read or write block transfer depends on the number of other block transfer modules on the same scanner channel that the program enable simultaneously Use the following procedure to calculate the time required for the PLC 3 processor to perform all block transfers on the channel and be ready to perform the first transfer again Block transfer times typically are similar regardless of the type of blo
189. operator when making on line moveset changes If the bitis on when the 1771 M3 controller receives the moveset the controller does not execute the moveset The controller continues to request the moveset until the data valid bit is off Bits 12 11 10 Moveset ID Bits 12 11 10 tell the 1771 M3 controller whether it is an odd or an even moveset block and also identifies the axis to which the moveset applies Chapter 7 Formatting and Interpreting Data Blocks Odd Moveset Block 001 010 011 These rules apply to moveset block ID assignment Figure 7 31 1 You must identify the first moveset block for axis as odd 001 for axis 1 010 for axis 2 011 for axis 3 2 The next move set pointer of any moveset block may point to the first moveset block for the axis Consequently the first moveset can point to itself 3 Except for rule 2 any moveset block with ID 001 must point to moveset blocks with ID 100 and moveset blocks with ID 100 must point to moveset blocks with ID 001 4 Except for rule 2 moveset blocks with ID 010 must point to moveset blocks with ID 101 and moveset blocks with ID 101 must point to moveset blocks with ID 010 5 Except for rule 2 a moveset block with ID 011 must point to a moveset block with ID 110 and a moveset block with ID 110 must point to a moveset block with ID 011 Consequently the movesets of a series for an axis typically alternate between even and odd IDs Figure 7 32 7 43 C
190. osition or Following Error Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 inch decimal point OO 0o o0 S Most significant digits aoc a BCD position or following error value 999 9999 inch or 19999 999 mm max lt Least Significant Position or Following Error Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Metric decimal poiont N __ Least significant digits 10 4 Chapter 10 Troubleshooting Turn on bit 11 to display the diagnostic status as shown in Figure 10 4 Also this diagnostic status displays automatically when the 1771 M3 controller detects an error in the parameter block immediately after power up or an invalid ID in a command block The diagnostic status displays automatically in that case because the error prevents you from selecting it thru the command block Figure 10 4 Position Following Error Diagnostic Words with Diagnostic Selected First Diagnostic Word Word pointer This BCD Error code This BCD number tells you which number references the word is in error within error listed in Table 10 A the block Second Diagnostic Word Block pointer This BCD number is the address of the block that is in error The second diagnostic word is the block pointer The block pointer is a BCD number that indicates the starting address of the block in error The 1771 M3 controller gets these block pointers fr
191. ou should first consider overall power distribution including the master control relay and loop contactor relay Figure 6 8 Connect a suppression network across each relay coil 6 13 Chapter 6 Installing the Assembly Figure 6 8 Simplified Power Distribution with the Master Control Relay Loop contactor Relay and Hardware Stop F F F u u S S S e e e e e e Ho c Ho Q oM DA H2 Isolation ann BUS 1Step Down tep Down Transformer Transformer EN X1 X2 F F F Extreme 2 Overtravel x Limit Switches Lolo O TIO o To O cru e LCR Mn Servo Drive Use any number of E stop switches series CRM Dynamic y Seats a r A CRM LCR Braking LCR b mS e Resistor LCR E e Pp E 3 RE AE e Backplane ise Power Supply Power Supply for Hardware Analog Output Circuit urs Stop CRM 15V DC Common 15V dc Servo Xformer Power Supply for Thermal Overload i Toa Ec C 1771 ES Expander RPM 5 30V dc Servo Drive CRM Fault x Servo Motor 1 0 Malules To Input Gircuits Thermal Overload LI 5 30V dc 2 Common NOTE El To minimize EM gener
192. ou want to connect 3 Push the jumper straight down If you position the jumper correctly it slides down over the pins easily Figure 6 2 Jumper in the Left Position 12014 6 4 Chapter 6 Installing the Assembly Selecting Discrete Input Resistance Select the resistance between each discrete input terminal and the high side of the input power supply To select 1 2k ohms set the switch on To select 11 2k ohms set the switch off Figure 6 3 Figure 6 3 Discrete input resistance Switch Assembly Jog Forward hardware start Jog Reverse Hardware feed ate habi Home Limit Stop Switch 1 2 3 4 ON ON ON 1 2kQ input OFF pull up resistance ON OFF 11 2kQ input pull up resistance OFF OFF ure zo 12015 With 1 2k ohms your input device must sink 4mA for a 5V power supply to 25mA for a 30V power supply With 11 2k ohms your input device must sink 0 5mA for a 5V power supply to 2 7mA for a 30V power supply Unless your input device cannot sink enough current select 1 2k ohms because it provides better noise immunity than an 11 2k ohms input resistance 6 5 Chapter 6 Installing the Assembly 6 6 Selecting Axis Number Select the axis number as shown in Figure 6 4 Figure 6 4 Axis number Switch Assembly Axis1 Axis 3 Axis 2 2 3
193. position preset word specifies the sign of the preset value O 1 Preset values are in BCD format The maximum value is 999 9999 in or 19999 999 mm Chapter 7 Formatting and Interpreting Data Blocks Figure 7 45 Position Preset Words Most Significant Position Preset Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 0 e inch ppp MENS Most significant digits oc onc 1 3 BCD position preset value 999 9999 inches or 19999 99 mm max Least Significant Position Preset Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 metric seconds Least significant digits 11029 Illegal Combinations Simultaneously setting certain bits in control words 1 and 2 for an axis results in a programming error sometimes with slide stop Table 7 D shows these bit combinations Programming error with slide stop PE Programming error without slide stop ws ET wes s Om E E senos s z E sl or a n Ia ROLE _ weH 2 06 5 p Pose FT L L Ecce States Imi Te IG fe ezi eniu Pla 60 genua a Eo mwj STE ERSTER METER RA E ooo suo
194. program the rapid traverse speed in this word 7 25 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 16 Gain Break Plot Emergency Stop Commanded Axis A Speed Rapid Traverse Speed corresponds to Analog Output Voltage specified in parameter block Gain Break Speed ao Reduced _ Initial Reduction Gain Gain Factor Slope IPM Mil Initial Gain Gain Break A Following Max Following Error Error 50 Feed Suppression Starts at 6 25 above max Following Error Excess Error Determined by Excess Following Error Parameter 11038 Gain Reduction Factor Bits 0 7 of the in position band and gain break factor word Figure 7 17 specify the gain reduction factor The initial gain of the axis is multiplied by this factor to obtain the reduced gain value for axis speeds above the gain break speed 7 26 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 17 In position Band Gain Reduction Factor Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 11 Axis 1 n Word 30 Axis 2 Word 49 Axis 3 Y This BCD value 99 max times 2 is Gain reduction factor the in position band in increments of feedback resolution 10 Gain Reduction Factor Reduced Gain Initial Gain For example if the initial gain is one and you want the reduced gain
195. r The PC processor transfers the entire parameter block to the 1771 M3 controller in response to the new parameter command However only the axis for which the new parameter command was issued receives updated parameter values words 7 thru 25 for axis 1 words 26 thru 44 for axis 2 words 45 thru 63 for axis 3 You cannot use the new parameter command to change the parameter block control word or address pointers This change requires reprogramming of the parameter block and re initialization of the system Bit 12 Moveset Override In the auto mode turn on bit 12 to generate a moveset override command This command provides you with a means of modifying the remaining move blocks of a moveset block while one of its moves is executing When you issue the moveset override command the 1771 M3 controller turns on the command taken bit and requests another transfer of the current moveset block unless the last move is executing After the servo positioning assembly receives the new copy of the moveset block to 7 71 Chapter 7 Formatting and Interpreting Data Blocks 7 72 replace the old copy it continues executing the moveset block starting with the next move block If you had changed the remaining move blocks in the data table before transfer the 1771 ES expander executes the changed move blocks If the current block is completed before the servo positioning assembly receives the new copy of the moveset block the next move
196. r these output according to the module location address you enter These addresses specify bits of the input and output image table bytes that correspond to the 1771 M3 controller location 8 3 Chapter 8 Figure 8 2 Block Transfer Instructions for P 2 30 and Mini PLC 2 15 BLOCK XFER READ DATAADDR 030 MODULE ADDR 100 BLOCK LENGTH 01 FILE 110 110 BLOCK XFER WRITE DATAADDR 030 MODULE ADDR 100 BLOCK LENGTH 01 FILE 110 110 Data Address First possible address in accumulated vaue area of data table Module Address RGS R rack G module group S Slot number This value is stored in the data address word Block Length Number of words to be transferred 00 can be entered for default value or for 64 words File Address of first word in the file This value is stored in the 108bove the data address Enable Bit EN In the output image table word for the module Set on when rung containing the instruction is true Don Bit DN In the input image table word for the module Remains on for 1 scan following successful transfer Figure 8 3 shows an example of data table arrangement for a read block transfer Data table words assigned for block storage must not include reserved processor work areas That is you must ensure that you assign starting addresses for the block so that the words requested by the 1771 M3 controller do not include words in the processor work area If the
197. r time in ms TR PS PIO 2 RIO 0 5 4 These equations are valid for a data transfer rate of 57 6k bits s or 115 2k bits s 8 7 Chapter 8 8 8 For worst case calculations use the longest block transfer time Block Transfer Sequence As stated above the remote I O scanner can process only one block transfer per remote I O scan worst case If a system has N I O chassis with block transfer modules a block transfer for a given chassis occurs once each N system scans If a given chassis contains X block transfer modules block transfer for any one of them occurs once each N x X remote I O scans For example consider a system with 4 I O chassis each of which contains one or more block transfer modules chassis 1 modules A B C chassis 2 modules D E chassis 3 module chassis 4 modules G I The block transfer sequence for this system is ADFEGBEFHCDFIAEFGBDFHCEFI Note that block transfer for modules A B and C occurs once each 12 system scans 4 chassis x 3 modules Block transfer for modules D and E occurs once each 8 system scans 4 chassis x 2 modules and so on Example Calculation Consider the PLC 2 30 remote system of Figure 8 4 This system has four I O chassis each of which holds one 1771 M3 controller module The ladder diagram program is 4K words long Calculate the worst case time between write block transfers for one of the 1771 M3 controller modules in the followi
198. ransfer times TW 0 1ms 0 16ms word 64 words 10 34ms TR 0 1ms 0 16ms word 10 words 1 7ms 4 Calculate time between write transfers TBT 2 PS TR TW 96 10 34 1 7 108 04ms Figure 8 5 shows the formats of block transfer instructions for a PLC 3 processor For each block transfer instruction you must specify O rack O module group within the I O rack I O module slot within the I O module group 8 13 Chapter 8 PLC 3 Block Transfer Timing Figure 8 5 Block transfer Instructions for PLC 3 Controllers BTR BLOCK XFER READ RACK 001 GROUP 1 MODULE 1 HIGH DATA F1001 0005 LENGTH 0 CNTL FB001 0000 BLOCK XFER WRITE RACK 001 GROUP 1 MODULE 1 HIGH DATA FO001 0004 LENGTH 0 CNTL FB001 0000 Block transfer instructions use two files when transferring data and commands between the block transfer module and the PLC 3 processor a data file that contains data being transferred acontrol file that contains control bits module location data table address and length of the data file The I O scanner directs communication between the block transfer module and processor Once the block transfer instruction is enabled the scanner directs the transfer of data to or from the enabled block transfer module according to the information contained in the instruction s control file Once the instruction is enabled the PLC 3 processor automatically sets and resets the c
199. rd 55 Axis 3 inch Sign decimal 0 point 1 Loss of feedback Most significant digits detection External 0 disable synchronization of 1 enable feedrate overide 0 disable BCD home position value 1 enable 999 9999 inches or 19999 99 mm max Home Position Least Significant Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 18 Axis 1 Word 37 Axis 2 Word 56 Axis 3 metric decimal Least significant digits point Global Accel Decel Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 19 Axis 1 P Word 38 Axis 2 Word 57 Axis 3 9 inch metric decimal decimal oint point p BCD global accel dec rate 9999 ipm s or 99 99 mpm s max Decel Step Rate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 20 Axis 1 n Word 39 Axis 2 Word 58 Axis 3 V inch metric decimal decimal Multiplier point point 1 1 A This BCD value 0 999 ipm or 010 x 10 19 99 mmpm max times the 100 x 10 multiplier is the decel step rate n X i 0 During deceleration the axis feed X rate steps directly to zero once the rate drops to this level This only applies to jog and search home C 5 Appendix C Parameter Block Software Travel Limit Word 21 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 40 Axis 2 Word 59 Axis 3 metric inch decimal decimal point point Posi
200. rse Rate Parameters 13 High Jog Rate for Axis 1 14 Low Jog Rate 15 96 Excess Following Error D A Vlotage 16 96 Excess Following Error D A Voltage 17 Home Position MS 18 Home Position LS 19 Global Accel Decel Rates 20 DecelStep Rate 21 Software Travel Limit 22 Software Travel Limit 23 Backlash Take up 24 Offset 25 FEReduction Tach Conversion Factor 26 Words 26 44 specify same parameters Parameters as words 7 25 but for Axis 2 Values for Axis 2 4 4 may be different 45 Words 45 63 specify same parameters Parameters as words 7 25 but for Axis 3 Values for Axis3 63 may be different Y 7 18 Chapter 7 Formatting and Interpreting Data Blocks The size of the parameter block you must provide depends on the number of axes Size of Number of Axes Parameter Block 2 44 words Your program must transfer the parameter block at power up After that the 1771 M3 controller calls for your program to send the parameter block again only when you issue a new parameter or reset command Parameter Control Word The parameter control word Figure 7 9 identifies the block as the parameter lock bits 10 17 specifies the units as either inch or metric bit 7 identifies the number of axes in the system bit 0 1 and 2 Figure 7 9 Parameter Block Control Word Parameter Block Control word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Wordi
201. s bit when you calibrate the tachometer input Also you would not use rungs to control bits 17 16 15 and 14 control word 1 ID of axis control word 2 because you must always have them set to the binary value 1100 Rung 61 Rung 61 performs no logical function in the program However this rung lets you display and enter values for all three moveset blocks for axis 1 You can display all three blocks at the same time on the industrial terminal by using its display function Rung 62 Rung 62 performs no logical function in the program However this rung lets you display the parameter command and status block and enter values for the parameter and command block You can display all three blocks at the same time on the industrial terminal by using its display function Rung 63 Rung 63 performs no logical function in the program However this rung lets you display and enter values for the moveset block for axis 2 You can display the block on the industrial terminal by using its display function Rungs 64 and 65 Rungs 64 and 65 are block transfer timeout rungs If a block transfer is not completed within three seconds bit 15 of TON 0051 goes on causing output 02400 to be latched on This output can be used to turn on a warning device 8 37 Chapter 8 8 38 Planning Data Blocks for PLC 3 With a PLC 3 processor the most straightforward way to arrange the data blocks is to put them all in the same file and use the addr
202. s in bits 12 11 and 10 of moveset control word Position 11016 3 The escape moveset block cannot be executed as part of a sequence of moveset blocks 7 45 Chapter 7 Formatting and Interpreting Data Blocks 7 46 The PC processor transfers the escape moveset block to the 1771 M3 controller at power up and after a reset or escape command is executed When it receives the escape moveset block the 1771 M3 controller immediately transfer the escape moveset block to the 1771 ES expander which stores it on board The escape move is not executed unless you issue an escape command via the command block When you issue the escape command the 1771 ES expander executes the escape move previously stored on board If another move is being executed when you issue the escape command the 1771 ES expander stops executing the current move and starts to execute the escape move Immediately after you issue the escape command the 1771 M3 controller requests transfer of the moveset for that axis controller requests transfer of the moveset for that axis identified in the parameter block If this is still an escape block the 1771 M3 controller transfers it to the 1771 ES expander for storage and requests transfer of another moveset from the PC processor The moveset requested is the one specified by the next moveset pointer of the escape moveset If you issue a command such as start begin or next move after execution of the escape moveset is
203. s situation In Figure 7 43a the axis is able to accelerate to the final rate for the next move and continue moveset execution In Figure 7 43b the axis cannot accelerate to the final rate for the next move but does continue moveset execution In Figure 7 43c the servo positioning assembly moves the axis to the endpoint of the next move using the accel final and decel values for that move then continues moveset execution Note that in all cases the axis attempts to move to the endpoint of the move that follows the EOM stop move 7 65 Chapter 7 Formatting and Interpreting Data Blocks Figure 7 43 Moveset Profiles Showing 3 Possibilities of Jogging After and EOM Stop Move 1 Move 2 Move 3 EOM Stop Command Rate N A Axis attains final rate of next move Start __ __ _ Final Position Command Jog of Move 1 Move 4 Move 1 Move 2 Move 3 EOM Stop commend Rate B Axis does not attain final rate of next move Final Position Start of Move 1 Command Move 4 Move 1 Move 2 Move 3 EOM Stop Command 4 Rate C Axis jogged beyond endpoint of next move E Jog 5E 3 Final Position Final Position of Move 1 ofMove 2 Command x Move 4 11027 7 66 Chapter 7 Formatting and Interpreting Data Blocks Bit 3 Search Home In the manual mode turn on bit 3 to generate a search home command When you
204. s to the error in error within the block listed in Table 7 A Second Diagnostic Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 S Block pointer This BCD number is the address of the block which is in error B 3 Doar o0 12 17 18 19 20 21 22 23 24 25 26 44 45 63 Parameter Block Appendix Parameter Block Control Word Parameter Block Pointer Command Block Pointer Moveset Block Pointer Axis 1 Moveset Block Pointer Axis 2 Moveset Block Pointer Axis 3 Fixed Overhead Feedback Resolution Encoder Lines Feedback Mult Encoder Lines Mult Initial Gain Gain Break Speed In Position Band Gain Reduction Factor Rapid Traverse Rate High Jog Rate Low Jog Rate Excess Following Error D A Vlotage Excess Following Error D A Voltage Home Position MS Home Position LS Global Accel Decel Rates Decel Step Rate Software Travel Limit Software Travel Limit Backlash Take up Offset FE Reduction Tach Conversion Factor Parameters for Axis 1 Words 26 44 specify same parameters as words 7 25 but for Axis 2 Values may be different Parameters for Axis 2 Words 45 63 specify same parameters as words 7 25 but for Axis 3 Values may be different Parameters for Axis 3 C 1 Appendix C Parameter Block Parameter Block Contro
205. se following error resulting in 5096 feedrate reduction but has not necessarily reached the excess error point When axis following error does reach the excess error point the feed reduction bit stays on and the immediate stop status bit goes on Important If the excess error point is less than 106 25 of rapid traverse following error immediate stop occurs before feed reduction Consequently the feedrate reduction bit in the status block does not turn on Bit 13 14 and Travel Limits These bits are on when the axis is at the corresponding software travel limit positions You enter the travel limits in the parameter block Bit 15 Insufficient Data When the servo positioning assembly receives a command to execute axis motion such as start or begin but does not have moveset data to execute a move it turns on the insufficient data bit It also turns on this bit when you issue an escape command even though you had never stored an escape move on the 1771 ES expander This insufficient data bit stays on until the 1771 M3 controller receives a new moveset block and then a start or begin command 7 9 Chapter 7 Formatting and Interpreting Data Blocks 7 10 Bit 16 Loss of Feedback This bit is meaningful only if you enable the loss of feedback detection feature by setting bit 15 of the most significant home position word of the parameter block If loss of feedback is enabled and the servo positioning assembly detects
206. sitioning assembly its specifications and its compatibility with other hardware components you will need for a closed loop positioning system 6 Installing the Assembly installing the servo positioning assembly and interconnecting hardware 7 Formatting and formatting parameter move description Interpreting Data Blocks control data for block transfer to the servo positioning assembly interpreting status and diagnostic data received in block transfer from the servo positioning assembly 8 Programming generating a ladder diagram program to transfer data blocks between the PC data table and the servo positioning assembly 9 Integrating Axes adjusting the servo positioning assembly for optimum operation with the machine axis it is to control 10 Troubleshooting using indicator status and status block information to diagnose and correct problems Chapter Objectives What is the Servo Positioning Assembly Introducing the Servo Positioning Assembly This chapter gives you an overview of the servo positioning assembly its applications functions and features A servo positioning assembly controls the motion of one of your axes It consists of one Servo Controller Module cat no 1771 M3 one Servo Expander Module cat 1771 ES that includes two Field Wiring Arms cat no 1771 WB With a basic servo positioning assembly plus a servo drive motor tachometer and encoder you can control the motion of one
207. t WB055 0000 15 and 05 and the block transfer read request bit WB055 0000 17 assures that the read alternates with the write The data file address for the block transfer read is always the address of the status block The data file address of the block transfer write is controlled by rungs 1 and 2 The control file address must always be in the binary section of the data table In addition to the rungs in Figure 8 17 you need a rung to clear the block transfer control word as shown in Figure 8 10 You also need rungs to perform the logic of rungs 5 thru 60 64 and 65 in Figure 8 16 In this chapter we told you about block transfer instructions and block transfer timing We also described programming examples However you must not run an axis with your program until you first follow the axis integration procedures we give you in chapter 9 Chapter Objectives Open Loop Procedure Integrating Axes You must perform the procedures in this chapter before you have the servo positioning assembly in service that is to help ensure that axes respond correctly to commands from the servo positioning assembly and that adequate feedback is provided to the 1771 ES expander module You must enter the parameter block before you perform these integration procedures In addition the ladder diagram program for the axis must be loaded in the PC Important For these procedures to work servo drives and motors must be capable of controlling
208. t switch causing emergency stop shut power off manually back the axis off the limit switch then issue a reset command thru the command block to re initialize the axis 17 Run the axis at increasing speeds in both directions Check for smooth axis motion There should be no mechanical vibration or cogging If there is take appropriate corrective action 18 Verify that 1 2 maximum servo output voltage 1 2 rapid traverse voltage causes axis motion at approximately 1 2 maximum speed 1 2 rapid traverse speed Check this for both directions of axis motion You may have to adjust the servo drive to satisfy this requirement Refer to the servo drive manufacturer s instructions 19 Turn off bits 11 and 15 of axis control word 2 in the command block This selects current position readout so the last two words of the status block indicate axis position 9 5 Chapter 9 Integrating Axes Closed Loop Procedure 9 6 20 21 22 23 While monitoring axis position in the status block move the axis slowly in both directions When the axis moves in the positive direction axis position should increase in the positive direction When the axis moves in the negative direction axis position should change in the negative direction As the axis crosses the zero position while moving in the positive direction the sign bit bit 17 of the most significant axis position word should change from on negative to off positive a
209. t move starts with the feedrate of the previous move rather than zero Software travel limit values are axis position values Note that if zero is the programmed travel limit value there is no software travel limit The absolute positions of the software travel limit vary with changes in axis position value due to preset or home commands In addition to the software travel limit you must have extreme axis overtravel limit switches wired in the master control relay circuit 7 35 Chapter 7 Formatting and Interpreting Data Blocks CAUTION If programmed values for software travel limits are zero there are no software travel limits To guard against damage to equipment use caution when operating an axis without software travel limits Figure 7 25 Software Travel Limit Words Software Travel Limit Word 21 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 40 Axis 2 Word 59 Axis 3 metric inch decimal decimal point point Positive software travel limit An axis position value in inches or meters BCD format Software Travel Limit Word 22 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 41 Axis 2 Word 60 Axis 3 metric inch decimal decimal point point Negative software travel limit An axis position value in inches or meters BCD format CAUTION If programmed
210. t when the axis feed is done after any command to move to the home position if you have established a home position You establish a home position through an initialize home or search home command This bit turns off when the axis moves away from the home position Bit 7 Auto Manual This bit indicates the current mode of the axis based on the status of the auto manual bit word 1 bit 7 in the command block 1 auto O 2manual Bit 10 Immediate Stop When this bit is on it indicates that the 1771 ES expander is holding its analog output signal at zero and is disabling the servo drive through its drive disable output You can clear this immediate stop condition through a reset command or by cycling I O chassis backplane power off then on Commands and events that can cause the immediate stop condition are Chapter 7 Formatting and Interpreting Data Blocks software stop command hardware stop input open excess following error loss of feedback loss of power firmware or hardware watchdog timeout on 1771 ES expander Bit 11 Hardware Stop The 1771 M3 controller turns on this bit only if the hardware stop input of the 1771 ES expander is open Note that the immediate stop bit bit 10 is also on if this bit is on You can turn off this bit with a reset command or by cycling power to the I O chassis backplane Bit 12 Feed Reduction This bit goes on when axis following error reaches 106 25 of rapid traver
211. terpreting Data Blocks override will not start until you close the feedrate override enable input This allows you to synchronize the feedrate override on several axes Bit 7 Search Home Direction Use bit 7 to specify the direction the axis moves in a search home operation To make the axis move in this direction Then set bit 17 to Negative 0 Positive 1 Bit 10 Axis Feedrate Override Enable Turn on bit 10 to enable feedrate override for the axis If this bit is off feedrate override is disabled for all axis motion If it is on feedrate override is enabled only on those moves for which bit 7 of the SMCW is on Bit 11 15 Readout Select The third and fourth status words for an axis provide either current axis position following error or diagnostic information You can select which status to display by controlling the state of bits 11 and 15 of axis control word 2 Turn off bits 11 and 15 to display the current axis position Turn off bit 11 and turn on bit 15 to display the following error Turn on bit 11 to display the diagnostic status Bit 12 Return to Position In the manual mode turn on bit 12 to generate a return to position command When the servo positioning assembly is in the manual mode and this bit is on the axis jogs at the selected jog rate high or low to the position where the axis was last stopped during execution of a moveset If the axis had stopped in the middle of a move th
212. the bottom position to gate the marker with channel A and channel B This gives the marker signal a level of noise immunity However if you cannot select the polarity so that the marker on your encoder is always true at the same time as the channel A and B signals set the market logic jumper to the top position A package of plastic Keys cat no 1771 RK is provided as standard with each I O chassis When properly installed these keys can guard against the seating of all but a selected type of module in a particular I O chassis module slot Keys also help align the module with the backplane connector 6 7 Chapter 6 Installing the Assembly Each module is slotted at the rear edge Position the keys on the chassis backplane connector to correspond to these slots to allow the seating of the module Insert keys into the upper backplane connectors Position the keys between the numbers at the right of the connectors Refer to Figure 6 5 for the 1771 M3 controller keying position Refer to Figure 6 6 for the 1771 ES expander keying positions Figure 6 5 Keying Diagram for the 1771 M3 Controller Keying Bands 8 C 10 12 Between pins 2 and 4 18 e pins 8 and 10 20 11005 6 8 Inserting the Module Chapter 6 Installing the Assembly Figure 6 6 Keying Diagram for the 1771 ES Expander Upper Left Upper Right Connector Connector C
213. the endpoint programmed for move 4 The axis then immediately begins execution of move 5 at the programmed final rate 3 3 Dashed lines from move 4 or move 5 on figure show execution if move 4 were single step run or halt 2 Compare move 3 for which the final rate of the next move is higher than the final rate for move Continuous Run Because move 6 is in the opposite direction the axis decelerates at the rate programmed for move 5 so it reaches zero velocity at the programmed endpoint Execution of move 6 begins or immediately In this case execution is the same for both continuous and single step commands Single Step Run The axis decelerates at the programmed rate so that it stops at the programmed endpoint When on bit 16 has priority over bit 17 Single step or Continuous has no effect on this move No further axis motion occurs until a command is received in the motion control block Chapter 7 Formatting and Interpreting Data Blocks Bit 17 Single Step Continuous Bit 17 determines how the 1771 ES expander executes moves when the run halt bit is off run mode Single Step If you turn off this bit the move ends with deceleration to zero velocity If you turn off bit 16 run command the axis decelerates to zero velocity then continues moveset execution without waiting for a motion command from the command block If you turn on bit 16 halt command the servo positioning assembly ignores bit
214. through the I O scan the positioning loop is closed on the 1771 ES expander at the positioning loop summing point This allows the 1771 ES expander to provide a servo sample period of 2 4ms independent of I O scan You must describe the axis motion you want in moveset blocks in the data table You can enter a maximum of 21 separate move blocks in a moveset block Figure 4 3 4 Positioning with Allen Bradley Figure 4 3 A Moveset Block is Sent to the 1771 M3 Controller That Sends the Move Blocks Sequentially to the 1771 ES Expander Two Move Block register in the 1771 ES expander Current Move Next Move Move blocks sent in sequence as each current move is started Moveset block in the PC Processor data table Move 1 Move 1 Move 2 A complete moveset 21 Move 2 moves max is sent in a Move 3 single block transfer Move 3 Move 4 Move 4 e e e e e Move 21 Move 21 sj Moveset register in the 1771 M3 controller 12007 The PC processor sends a complete moveset block to the 1771 M3 controller in a single block transfer The 1771 M3 controller can hold a moveset block for each of the three possible axes The 1771 ES expander can hold two move blocks the current move block available for execution and the next move block After the current move is completed and the next move is to
215. tive software travel limit An axis position value in inches or meters BCD format Software Travel Limit Word 22 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 41 Axis 2 Word 60 Axis 3 4 i metric inch decimal decimal point point Negative software travel limit An axis position value in inches or meters BCD format CAUTION If programmed values are zero there are no software travel limits To guard against damage to equipment exercise caution when operating an axis without software travel limits Backlash Takeup Distance Word 23 Axis 1 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 42 Axis 2 Word 61 Axis a i inch metric decimal decimal point o Sign Distance axis overshoots when initial 0 approach to endpoint is from 1 E direction opposite that specified in bit Axis approaches all 17 endpoints moving in the direction specified by the sign bit 17 Offset Word24 Axis 1 47 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 43 Axis 2 Word 62 Axis 3 e um monie point Dont Offset value inches or uat millimeters BCD format 1 FE Reduction Tach Conversion Factor 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
216. to 9990 ipm bit 14 must be 0 for inch values Metric 0 001 to 199900 mmpm For example to program a local feedrate of 100 ipm you program 100 x 10s ipm Figure 7 37 Local Feedrate Word Local Feedrate Word Do not include this word if you select global feedrate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 e e inch metric Multiplier l 001 x 10 This BCD value 0 999 ipm or 000 x 10 19 99 mmpm max times the 010 x 10 multiplier is the local feedrate 100 x 10 110 x 107 111 x 10 1051 Local Accel and Decel Words If you turn on the local accel decel bit in the SMCW you must include local accel and decel words at the end of the move block These words specify acceleration and deceleration rates as 4 digit BCD values Figure 7 38 nch maximum value is 9999 ipm s 7 57 Chapter 7 Formatting and Interpreting Data Blocks 7 58 Metric maximum value is 99 99 mpm s Note that the units for this value are meters minute second not millimeters minute second Figure 7 38 Local Accel Word and Local Decel Word Local Accel Word Do not include this word if you select global feedrate 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 N metric inch Acceleration rate ipm sec or mpm sec meters min sec BCD format Local Decel Word Do not include t
217. to disconnect axis servo motor power if necessary If you hardwired an emergency stop circuit like that of Figure 6 8 the loop contactor relay will disable the servo motor when one of the switches in the E Stop string is opened However you must disconnect the drive disable line for open loop drive operation 9 3 Chapter 9 Integrating Axes 9 4 10 11 12 13 14 Disconnect the analog output and analog return leads from the 1771 ES expander wiring arm Zero the output of the battery box then connect its command output lead to the analog output lead just disconnected from terminal 3 Connect the battery box return lead to the analog return lead just disconnected from terminal 4 Figure 9 2 Leave the wiring arm up connected to the module CAUTION Zero the output of the battery box before connecting it to a servo drive Sudden application of command voltage to the drive could damage equipment Axis speed must increase gradually Disconnect the servo motor from the leadscrew Replace the axis fuses then re apply power to the axis and servo positioning assembly Leave de energized those drives for axes you are not integrating Turn off bit 15 enable loss of feedback detection of the home position value word in the parameter block While leaving the switch to the drive disable line open adjust the battery box output away from zero If you can get the servo motor to rotate there is something wrong with
218. to linear motion is with a leadscrew Figure 3 1 Figure 3 1 Leadscrew Converting Rotory Motor Motion Into Linear Axis Motion Axis Motion Slide z Motor C che 11999 The leadscrew assembly is referred to as the axis A leadscrew assembly consists of a long threaded shaft the leadscrew and slide having an internal thread that matches the leadscrew When the motor rotates the leadscrew clockwise the slide moves forward When the motor rotates the leadscrew counterclockwise the slide moves backward 3 1 Chapter 3 Positioning Concepts 3 2 Velocity Loop Most closed loop servo positioning installations use a dc motor to power the leadscrew To accurately control the velocity of the dc motor we need a velocity loop Figure 3 2 The velocity loop contains a summing point an amplifier and a tachometer A tachometer is a precision generator that produces a voltage signal directly proportional to the angular velocity of the motor shaft The output of the tachometer is the velocity feedback signal which is subtracted from the velocity command signal The difference is the velocity error signal that is amplified to provide power for the motor to run at the commanded velocity Figure 3 2 Velocity Loop Axis Motion lt gt TA gt Tach C Summing Point Amplifier Velocity Velocity Command Error Velocity Feedback
219. troller turns on this bit when the 1771 ES expander has finished feeding the axis for a programmed move or finished a dwell Bit 2 Ready The 1771 M3 controller turns off the ready bit after power up or after you execute the reset command The controller turns on this bit when it receives valid parameter block values When the ready bit is on the 1771 M3 controller is ready to respond to commands you issue through the command block 7 7 Chapter 7 Formatting and Interpreting Data Blocks 7 8 The processor must not transfer the command or moveset blocks to the servo controller until the ready bit is on Bit 3 Hardware Jog Hardware Start The 1771 M3 controller turns on this bit when the 1771 ES expander recognizes a jog plus or hardware start input signal Bit 4 Slide Stop The 1771 M3 controller turns on this bit when it receives a slide stop request from the command block word 1 bit 5 The slide stop status bit stays on even after the slide stop command is no longer present in the command block This bit turns off when you command axis motion or reset A reset command while the axis is in motion will also turn on this bit and cause a slide stop When the axis stops this bit turns off Bit 5 Hardware Jog Feedrate Override Enable The 1771 M3 controller turns on this bit when the 1771 ES expander recognizes a jog minus or feedrate override enable input signal Bit 6 Home The 1771 M3 controller turns on this bi
220. tween consecutive block transfers for a given module is consequently system scan time plus the sum of the individual block transfer times of the modules in the system Time Between Transfers system scan time T2 Tn where T1 T2 Tn are individual block transfer times System scan time for a PLC 2 30 local system is program scan time PS plus processor I O scan time PIO PS z 5ms K word x program length PIO Ims chassis x number of chassis You can calculate individual block transfer times with this formula T 0 1ms 0 075ms word x block length The same formula applies to both read and write transfers As an example consider a PLC 2 30 local system with four I O chassis each of which holds one 1771 M3 controller module and no other block transfer modules User program length is 4k words To calculate the worst case time between consecutive write block transfers for one of the 1771 M3 controllers follow these steps 8 11 Chapter 8 8 12 1 Write down known values program length 4K words number of chassis 4 block length 64 words write 10 words read 2 Calculate system values program scan time PS Sms K word 4K words 20ms processor I O Scan time PIO 1ms chassis 4 Chassis 4ms 3 Calculate individual block transfer times Write TW 0 1ms 0 075ms word 64 words 4 9ms Read TR 0 1ms 0 075ms word 10 words 0 85 ms These tim
221. user supplied machine axis You can add a second 1771 ES expander to control a second axis and a third 1771 ES expander to control a third axis A 1771 I O chassis can accommodate one 1771 M3 controller and a maximum of three 1771 ES expanders The 1771 M3 controller requires one I O chassis slot it requires no wiring figure 2 1a You can install it at any I O slot in the I O chassis The 1771 ES expander requires a pair of slots that make up an I O module group Figure 2 1b You make all wiring connections to the 1771 ES expander 2 1 Chapter 2 Introducing the Servo Positioning Assemb Its Applications Its Function 2 2 Figure 2 1 Servo Positioning Assembly a Servo Controller Module b Servo expander Module cat no 1771 M3 cat no 1771 ES 17954 Typical applications for a servo positioning assembly include positioning for grinding transfer lines material handling drilling riveting rotary indexing V belt cutting glass cutting Figure 2 2 shows a servo system for closed loop axis control The 1771 M3 controller communicates with the 1771 ES expander through I O chassis backplane connections Chapter 2 Introducing the Servo Positioning Assembl
222. value in the position register to see if it is an even multiple of the number of feedback increments per revolution If the value is off the 1771 ES expander will automatically adjust it to the closest even multiple This auto position correction feature corrects position errors caused by noise on the channel A and B encoder feedback signals However the function of this feature assumes a noise free marker signal Although this feature may be able to prevent an accumulation of position error caused by occasional noise on the channel A and B inputs it cannot maintain position accuracy if the environment is excessively noisy or if the cabling and shielding is not proper If the environment is excessively noisy or if the cabling and shielding is not proper this feature will cause the axis to jump or jerk This jump or jerk indicates a problem Note that when the module detects a position error it does not necessarily disable the servo drive Specifications Chapter 5 Hardware Description Because this feature adjusts the position register to the closest even multiple of the number of feedback increments per revolution it is essential that the axis move less than half an encoder revolution per servo sample period 2 4ms Therefore to avoid a programming error you must limit the axis speed to conform to this formula programmed 12 500 exceeds x FR x FM x EL P 1 28 Where FR feedback resolution FM feedback multiplier
223. value without causing axis motion This action effectively shifts the axis position scale Figure 4 11 shows an axis position scale before and after a preset operation Figure 4 11 Axis Position Scale before and after Preset After Preset 1 5 Before Preset 11009 4 12 Summary 4 Positioning with Allen Bradley Initialize Home Through a command block you can generate an initialize home command The initialize home operation assigns the home position value which you specify in the parameter block to the current axis position Its effect is the same as that of the preset operation except that the new position value is the home position value Now that you have been familiarized with the general concepts of how the servo positioning assembly functions in a closed loop positioning system and in a PC system you are ready for specific details of the servo positioning assembly in chapter 5 4 13 Chapter Objectives Indicators Hardware Description The previous chapter described how the servo positioning assembly fits into a positioning system as part of a programmable controller This chapter describes specific hardware of the servo positioning assembly and lists its specifications This chapter also describes other hardware items you need for a positioning system There are three indicators on the 1771 M3 controller With the PC processor operating in the run mode the indicators have the
224. vel limit Jog speed is either high or low as determined by bit 14 of the second control word for this axis You specify high and low jog speed values in the parameter block The axis accelerates to jog speed and decelerates from it at the global rate value you specified in the parameter block If you use the decel step velocity parameter block it applies to deceleration from jog rates Bit 2 Begin In the auto mode turn on bit 2 to generate a begin command This command causes the servo positioning assembly to discontinue executing the current move and start executing the active moveset at its first move block regardless of what move block is executing If the axis is moving and the endpoint of the first move of the moveset is in the same direction as the axis motion then the axis will smoothly 7 63 Chapter 7 Formatting and Interpreting Data Blocks accelerate or decelerate to the final rate for the first move in the current moveset and continue moveset execution If the axis is moving and the endpoint of the first move of the moveset is in the direction opposite that of axis motion the servo positioning assembly 1 executes a slide stop 2 moves the axis to the endpoint of the first move in the current moveset using the values programmed for that move 3 continues moveset execution If the servo positioning assembly is executing an escape move when you issue the begin command it ignores the begin command If you
225. wer supply for the I O chassis backplane the power supply for the analog output circuit Figure 6 18 shows a grounded ac system the low side of the isolation transformer is connected to the central ground bus Figure 6 18 also 6 30 Chapter 6 Installing the Assembly shows connections from the central ground bus to each chassis and to the I O chassis ground bus shown in Figure 6 17 Start up Sequence Figure 6 18 AC Power and Ground Connections Incoming H1lH2 H3 H4 H7 Ha H1 Isolation Transformer Bulletin 1388 120V AC Power X1 4 xil d Transformer X2 round Bus e RN 120V AC ccc ble rf x 2 Y1 Fis 35 5V ac x A3TB1 7 8 9 A2TB1 Li N Li N Li N 11 10 Bulletin 1388 Ge Ge Ge 9 DC Servo Controller Power Power t 15V dc Drive Supply Supply for For DAC for Input Chassis Customer Circuits Backplane Supplied 4 5 Return 6 1 0 Chassis Ground Bus Motor 17966 After properly installing your servo positioning assembly formatting
226. xecutes immediate stop before following error reaches 106 2596 of rapid traverse following error and D A Voltage Bits 00 thru 13 in words 15 and 16 34 and 35 53 and 54 specify the maximum servo output voltage that is available to command rapid traverse feedrate in the positive and negative directions Figure 7 21 Enter values for these parameters in BCD format in the range of 0 01V to 9 99 V Programming 0 causes the D A voltage value to default to 10V Initially set them to the maximum value the servo drive will accept The plus and minus D A voltage values needn t be equal You can enter them as different values to compensate for directional differences in drive performance during axis integration chapter 9 Home Position Value Words 17 and 18 36 and 37 55 and 56 specify the axis home position value Figure 7 22 Bits 0 through 14 of the first word contain the most significant digits Bit 17 of the first word specifies the sign of the home position value When the servo positioning assembly performs a search home or initialize home operation it sets the axis position register to the value you enter for this parameter Chapter 7 Formatting and Interpreting Data Blocks Figure 7 22 Home Position Words Most Significant Home Position 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Word 17 Axis 1 Word 36 Axis 2 b Word 55 Axis 3 iE inch
227. xis feedrate accelerates before reaching the final velocity rate This allows a smooth start up after a hardware stop Do not provide switch contacts in the hardware stop circuit for an operator to turn off the axis motion Opening the hardware stop circuit stops the axis abruptly stressing the servo drive the servo motor and the mechanical linkage just as the CRM would Use the hardware stop input only for backup to inform the 1771 ES expander of a condition that has already stopped the axis so that the expander can provide a controlled start up Connecting Home Limit Switch To connect a home limit switch follow these steps 1 Connect a normally open limit switch between the home limit switch terminal and common 2 Place the limit switch so that it closes as the axis reaches a point approximately one half of an encoder revolution from the point you want to establish as home position 3 Adjust the angular position of the encoder to have the marker pulse occur precisely at the point you want to establish as home position Through the command block transfer you can command a search home function sections titled Axis Control Word and Axis Control Word 2 The 1771 ES expander moves the axis to the limit switch decelerates the axis Chapter 6 Installing the Assembly establishes the point of the next marker pulse following the limit switch as the home position Stops the axis at the home position You
228. y can execute movesets you have programmed according to operator commands such as start begin next move EOM stop escape slide Stop Off Manual Mode In manual mode moveset execution is suspended and the servo positioning assembly can execute jog preset home and other manual mode commands Bit 10 Reset Turn on bit 10 to generate a reset command This command re initializes all axes when the servo positioning assembly is in manual mode Issue this command to recover from an immediate stop condition This command is not recognized and the status block indicates a programming error when this bit is on with the servo positioning assembly in auto mode If an axis is in motion when this command is issued the axis performs a slide stop at the global deceleration rate in the parameter block After the axis stops the 1771 M3 controller acknowledges the command through the status block Important The reset command affects all axes controlled by a 1771 M3 controller Motion of all axes must stop before the reset command is acknowledged The reset command is similar to power up That is all 1771 M3 controller memory is cleared by a reset including presets and accumulated offsets However it is unlike power up in that the actual position is maintained on the 1771 ES expander Of course if an external power supply loss occurs you must perform a search home operation after a reset to re initialize the axis Bit 11 Offset Tur
229. y stop the hardware stop input goes high This forces the module to hold the velocity command output signal at zero and disable the servo drive by turning off the drive disable circuit Therefore if a connection in the hardware stop circuit breaks the 1771 ES expander will disable the servo drive 5 9 Chapter 5 Hardware Description 5 10 Loss of Power The 1771 ES expander holds the velocity command output signal at zero and disables the servo drive by turning off the drive disable circuit if it is unable to sense the specified voltage as the following power supply terminals positive terminal for the input power supply common terminal for the input power supply positive terminal for the analog power supply negative terminal for the analog power supply Therefore if one of these power supplies connected to the 1771 ES expander terminal fails or if one of these connections from these power supply breaks the 1771 ES expander will disable the servo drive The drive disable circuit normally provides current to a sensing circuit on the servo drive to enable it However if the 1771 ES expander detects a fault it cuts off the current in the drive disable circuit thereby disabling the servo drive Therefore if a connection in the drive disable circuit breaks this disconnection will disable the servo drive Auto Position Correction Each time the 1771 ES expander receives a marker pulse it checks the

1771-6.5.25, Servo positioning Assembly User Manual

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