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User Guide Rev. A

1. Name Servo Module Icon Country region Sweden 146 123 Area code Phone number Connect using AAA Cancel Servo Module Properties afd ConnectTo Settings Port Settings M Function arrow and ctrl keys act as e Terminal keys T Windows keys Bits per second 5700 y Data bits e y Parity None Stop bits h y Flow control M Backspace key sends CH Del Ctr H Space Ctri H Emulation Auto detect y Telnet terminal ID JANS Backscroll buffer lines 500 Terminal Setup Play sound when connecting or disconnecting Input Translation ASCII Setup Restore Defaults Cancel Servo upgrade module userguide doc Copyright 2010 Page 10 of 30 Select 57600 baud 8 databits 1 stopbit and no flow control Finally go to File menu and select Properties click the ASCII Setup button and tick the checkbox for echoing typed characters locally Power up the drive and you should see a message on screen now type lt ENTER gt and the module should respond with the setup menu Die siel nis P Kp 450 I Ki 18 D Kd 2000 T Ti 1 Y V ff A A FF 0 N Multiplier 1 L N A 1 E Error limit 75 C Max PWM 380 F Error scale 0 Output Offset Y Encoder filter 2 5Mhz Peak error abs N N TE N FE NI N IE IE HE
2. Get Velocity This gets the current motor velocity in encoder counts per servo loop cycle It s presented as a signed value GV lt ENTER gt Velocity 63 4 6 2 GP Get Position This gets the current motor position Currently it s being presented as two 16bit numbers corresponding to the the high and low word of the internal 32bit position register GP lt ENTER gt Pos 3 46259 In the above example the actual motor position is 3765536 46259 242867 encoder counts The 32bit position register is signed 2 s compliment meaning that if the most significant bit is set the number is negative 4 6 3 GT Get Target setpoint This gets the current target position or setpoint GT lt ENTER gt Setpoint 3 46259 As with the GP command the setpoint is preseneted as two 16 bit numbers representing the high and low word of the internal 32bit setpoint register Servo upgrade module i Page 15 of userguide doc Copyright 2010 age 15 of 30 4 6 4 GE Get Error This gets the current error ie Setpoint Position It s presented as a signed value GE lt ENTER gt Error 8 4 6 5 GF Get scaled limit This gets the actual following error trip limit as calculated based on the currently commanded motor velocity the following error trip limit the E parameter and the following error scale value the F parameter GF lt ENTER gt Scaled limit 36 4 6 6 GO Get Output This gets the
3. This bit will be set when an external fault issued thru the external fault input has stopped the operation of the servo loop Bit 7 Data recorder mode This bit will be set when the module is in data redcord mode Servo upgrade module i Page 17 of userguide doc Copyright 2010 age 17 of 30 Bit 8 Data recorder trigged This bit will be set when the module is in data record mode and in process of recording data to the internal buffer Bit 10 PWM Output saturated This bit will be set if the output at one point or another since power up or reset has been saturated When this happens it means that the servo loop no longer have the motor under control It the servo loop would like to apply more power in order to reduce the error but it simply can t because the duty cycle already is at its max which means that error is likely to grow bigger instead of smaller Bit 11 Commanded motor direction This bit will be set when the commanded motor direction is in the negative direction It is being used internally for the data recorder mode Bit 14 UART Receive error This bit will be set if the internal hardware UART has detected an error when receiving data on the serial line like buffer overruns etc This SHOULD never happen Bit 15 UART Transmit error This bit will be set if the internal hardware UART has detected an error when transmitting data on the serial line this could happen if the firmware in the modul
4. 5 24 128 157 Once the trig condition is met the module will start to record the value you ve selected into the buffer Once the buffer is full 128 entries the recording will automatically stop and the data will get sent to the host You can then copy paste them into EXCEL etc To abort the data record mode simply send Z lt ENTER gt The data recorder mode can be used to analyze the step response of the motor and evaluate different tuning settings Activate the data recorder mode with the trig source set to 0 and use the or commands to issue instant relative moves Here s an example EXCEL plot of three such a moves with different PID parameters g because the internal servo loop is not running If the module is issued a soft reset the R command the recording will continue and the data will be sent once the buffer is full If you want to abort the recording simply send Z lt ENTER gt before you Servo upgrade module userguide doc Copyright 2010 Page 26 of 30 4 21 Menu This prints the menu with all showing all changeable settings and their current values 4 22 Relative move Enter 100 to make a move corresponding to 100 encoder counts in the positive direction Enter 75 to make a move corresponding to 75 encoder counts in the negative direction This is an instant or step move no trajectory planning acceleration deceleration are being performed 125 lt ENTER gt
5. External fault reguest RS BEER ES AUG DAE AN TA ONE E Servo abort O command di EDEN Vad oe a EE ya ONE EEN OAK ee es 2 2 6 PWM Duty cycle and output swing The UHU chip limits the output duty cycle or output swing to between 13 and 87 in order to allow the bootstrap capacitors in the bridge drive enough time to refresh their charge By default the modules C parameter is setup to provide the same amount of outpput swing as the UHU Chip However if the hardware on which the module is being used can accept a larger output swing it is possible to increase the it up to 8 92 See the command reference section of this manual for details on the C parameter 2 2 7 Baud rate The original UHU chip uses 34800baud 8N1 for serial communication with the host PC The servo processor upgrade module uses 57600baud 8N1 This means that its not possible to use any terminal software specifically developed for the UHU chip with this module Any general purpose terminal software such as Hyperterminal and Realterm will work if setup for 57600 8N1 See section 3 1 for further details on how to set up the terminal software 2 2 8 Parameter banks The original UHU features several banks to which complete sets of settings can be saved and recalled This module only have one single bank Servo upgrade module userguide doc Copyright 2010 Page 8 of 30 3 Installing the module The module consists of a printed circuit board with pin heade
6. Move 125 The and commands can be useful in conjunction with the data recorder mode to anaylze the step response of the system see the Z command Note If the commanded move is larger than the currently set following error trip limit the E parameter the module will enter fault state immediately The step multiplier setting has no effect on moves issued with the and commands all moves are in direct encoder counts 4 23 Peak Error The peak error shown on the last line in the menu is not a settig or parameter It s simply the largest following error detected since power on or module reset Servo upgrade module userguide doc Copyright 2010 Page 27 of 30 Appendix A Intentionally left blank Servo upgrade module userguide doc Copyright 2010 Page 28 of 30 Appendix B Following error scale The following error scale setting allows the following error trip limit to be scaled proportionaly to the commanded motor velocity Each servo update cycle the commanded velocity is calculated in encoder counts This value is then multiplied by the following error scale value the F parameter and divided by 256 Finally it is added to the value of the E parameter and compared to the current difference between target position and actual motor position ie the following error Let s say your motors rated velocity is 2500rpm and that you have a 4000 counts revolution 1000 lines or cycles encoder mounted
7. e The PWM output saturated flag in the status register is cleared e The detected peak error value is reset e The setpoint register is loaded with the current motor position ie the current motor position becomes the new setpoint and therefor the current error becoms 0 e The Fault output is returned to its normal state high Servo upgrade module userguide doc Copyright 2010 Page 21 of 30 e The Enable output is turned on set high enabling power to the motor on a typical UHU based design R lt ENTER gt Servo RESET 4 15 S Save parameters This saves all parameters to the on board non volatile memory While there are several banks available on the UHU chip the servo processor upgrade module only has one bank S lt ENTER gt Parameters saved g p y p triggers the execution of the servo loop is temporarily turned off as it otherwise can cause coruption of the data being written to the EEPROM memory Because of this the S command is only allowed to execute when the motor is not commanded to 4 16 T Integral time constant Ti The T command is used to set the time constant for the PID filter integrator A value of 1 default means that the I term is updated every time the PID loop is executed A value of 2 means it s updated every second run of the PID loop and so on The frequency at which the PID loop is exectued is controlled by the L parameter T3 lt ENTER gt T Ti 3 Servo upgrade modu
8. or the value to which the encoder filter setting is set which ever is lowest See the Y parameter Servo upgrade module i 23 of userguide doc Copyright 2010 Page 23 of 30 4 19 Y Encoder filter Sets the internal divider ratio for the encoder filter The modules microcontroler have a digital filter incorporated on the encoder input signals which can be setup to provide different amount of filtering There are 7 different settings available YO 2 5Mhz default Y1 1 25Mhz Y2 625kHz Y3 156kHz Y4 78kHz Y5 39kHz Y6 19 5kHz Entering a value higher than 6 will result in the filter getting set to 19 5kHz If your motor is rated 3500rpm and has a 2000counts rev encoder 500 lines the resulting encoder count frequency will be 3500 2000 60 117kHz If filtering is needed set the Y parameter to the nearest higher value which in this case would be 3 156kHz On a properly designed system there should be no need for any filtering If you don t experience any problems that you think is due to noise on the encoder signals you can safely leave the Y parameter at O default Differential signals over twisted pair cables with line drivers and receivers at their respective ends are recommended especially when using any combination of high resolution high speed and long cables Servo upgrade module userguide doc Copyright 2010 Page 24 of 30 4 20 Z Data recorder mode The Z command is
9. to set a value higher than 256 in which case the gains will get scaled UP when the error is within the antidither region if the user sees any application for that Setting the K parameter to 256 resulting in a gain of 1 will efecitvely disable the antidither feature in case it s not needed or desiried Servo upgrade module userguide doc Copyright 2010 Page 19 of 30 4 10 L Servo loop rate Sets the freguency at which the PID loop is ran There are 10 settings ranging from 0 to 9 0 2800Hz 5 1650Hz 1 2450Hz 6 1500Hz Default 2 2200Hz 7 1400Hz 3 1950Hz 8 1300Hz 4 1800Hz 9 1220Hz L7 lt ENTER gt L Loop 7 What the L parameter actually does is setting a ratio between the PWM frequency and the execution of the the servo loop The dividing ration is whatever L is set to plus 7 The PWM frequency is 19 5kHz so with L set to 3 the resulting servo loop rate is 19500 713 1950Hz Setting L to any value above 9 will result in a servo loop rate of 1220Hz 4 11 O Offset This sets the amount of offset applied to the output Normally the internal dutycyle value is 1024 representing 50 when no torque is required from the motor The O parameter offsets this up or down by the amount entered It can be used to compensate for directional unbalance when driving hanging loads like the Z axis on a typical three axis VMC or knee mill The value is entered in signed form ie O 25 lt ENTER gt O O
10. 15 4 7 INTEGRAL GAIN ta a EE ONSE SE GE DE 19 4 8 d ANTIDITHER RE OON A eae ee 19 4 9 K ANTIDITHER SCA CE td 19 41 0 1E SERVO LOOP BATE tddi 20 AAA O AE EE OR OR OE RO ER EO a iaa at 20 4 12 PEPROPORTIONALGAIN 2 00566 es ese SE eg ltd alias 21 AAS QS QUT SERVO SEE EERS SEE ESE A ed eia OE Ge TEN EE Dee Ve RE LE EE ve eed ee deeg 21 4 14 R RESETYIRESTARIT Hi EE Ne ee ee uid Ge de Ge oe Re ee ee ee Gede se Ak 21 4 15 Si SAVE PARAMETERS iese ee so Pe n bee es ee ee SE ee Se bee EE ee oe ge ee geed GEES indecisa 22 4 16 T INTEGRAL TIME CONSTANT Denia dd 22 4 17 V VELOCITY FEED FORWARD GAIN eeue ee ees ees ee ee ee ee ee ee ee ee ee ee ee ee RR ee ee ee ee ee ee ee ee ee ee ee 23 4 18 KESTEPIMULTIPEIERD Ee SE A ee ee ed ee ee ee de ee ee ee ee AA 23 4 19 Y ENCODEREILTER Re ed es SE ee ty Sevens ER Ge Se Oe dans Ge GE Ge EER Ee Se SES ae 24 4 20 Z DATA RECORDER MODE iese ees ee ee ee ees see ee n ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee 25 AR EER EE ER N NE a 27 4 22 4 RELATIVE MOVE cc SR Dee EE De ee encode Sa ee din led 27 Servo upgrade module userguide doc Copyright 2010 Page 2 of 30 4239 PEAK ERROR RE RE ER OE RE ER 27 APPENDDEASE ER EG GR SA tae Re GE Ee ee ies Re Ne ee Ss O 28 APPENDIX B FOLLOWING ERROR SCALE 1 0 0 2 sees ees ees see ee ee ee ee ee ee ee ee ee ee ee ke ee ee ee ee ke ee ee ee ekke 29 DOCUMENT REVISION HISTORY sees a ee ee ee ee ee ee ee e
11. FE IE IE IE IE IE IE N N IE IE HH HHH Actual content of menu may differ Servo upgrade module userguide doc Copyright 2010 Page 11 of 30 4 Command reference This section explains the various settings and commands that are available To change a setting simply type the letter corresponding to the setting you want to change followed by the value to which you want to change it and press lt ENTER gt The module will then respond with a confirmation For example to set the proportional gain you enter P1234 lt ENTER gt and the module responds with P Kp 1234 When all settings are to your liking the S command is used to save them to the on board EEPROM memory Simply send S lt ENTER gt and the module will respond with Parameters saved to EEPROM All settings accepts integer values only some uses signed numbers ie they can be set to negative values by preceeding them with a It is described in this manual when and where negative values are applicable No floating or fixed point numerical values are allowed simply no decimal points 4 1 A Acceleration feed forward Sets the acceleration feed forward gain The acceleration feed forward works like the derivative term of the PID filter but instead of working with the difference of the error between PID updates the acceleration feed forward works on the difference of the commanded velocity ie the acceleration giving the output some extra p
12. current output from the PID filter including velocity and acceleration feedforward but excluding any offset that has been applied with O command The value is presented in signed form GO lt ENTER gt PID Output 12 4 6 7 GD Get Dutycycle This gets the current dutycycle being output by the module The value is presented like it is being written to the internal PWM generator where a value of 1024 means 50 dutycyle GD lt ENTER gt PWM Dutycyle 1214 Servo upgrade module userguide doc Copyright 2010 Page 16 of 30 4 6 8 GS Get Status This gets the current status of the module It s presented as a 16bit binary number with the most significant bit to the left and the least significant bit to the right Bit 0 Fault Bit 8 Data recorder trigged Bit 1 Following error Bit 9 Bit 2 External fault Bit 10 PWM Output saturated Bit 3 Bit 11 Commanded motor direction Bit 4 Bit 12 Bit 5 Bit 13 Bit 6 Bit 14 UART Receive error Bit 7 Data recorder mode Bit 15 UART Transmit error GS lt ENTER gt Status 0000010000000101 The following describes each bit briefly Bit 0 Fault This bit will be set whenever the operation of the servo loop is inhibited ie power to the motor is turned off by making the Enable output low Bit 1 Following error This bit will be set when a following error larger than the E parameter any applied scaling the F paramater stops the servo loop Bit 2 External fault
13. e ee A aa ee ee aa ee ee ee 30 Servo upgrade module userguide doc Copyright 2010 Page 3 of 30 1 About this guide This document is divided into the following chapters Chapter 1 About this document Chapter 2 Introduction Chapter 3 Installing the module and verify that it is working Chapter 4 Command reference describes the modules commands Appendix A Appendix B The following error scale feature explained Appendix C 1 1 Who Should Use It This guide is intended for users of the servo module The user is expected to have a general understanding of how a closed loop servo system operates as well as general electronics and PC knowlege 1 2 Typographical Conventions This document uses the following typographical conventions Angle brackets are used to illustrate a button press such as lt ENTER gt Commands as entered by the user appears in italic like D1234 lt ENTER gt Response from the module as shown in the terminal software window appears in monospace font like D Kd 1234 Servo upgrade module userguide doc Copyright 2010 Page 4 of 30 2 Introduction 2 1 Purpose The purpose of the servo processor module is to be drop in replacement for the popular UHU servo controller chip Simply replacing the UHU chip with servo processor upgrade module allows current hardware to attain higher step rates and or use higher encoder resolutions than previously possible with the UHU c
14. e tried to send data when the UART is already in process of sending This SHOULD never happen Servo upgrade module userguide doc Copyright 2010 Page 18 of 30 4 7 Integral gain Sets the integral gain of PID filter I1105 lt ENTER gt 1 Kis 105 75 The value shown within paranthesis is the gain that will be applied when the error is within the antidither region See the J parameter and the K parameter 4 8 J Antidither region Sets the range or region which within the antidither function is active The antidither function works by scaling the P and D gains by an adjustable factor see the K parameter when the error is within what the J parameter is set to For example if the J parameter is set to 2 the antidither function will be active when the error is within 2 counts See the K parameter regarding what to do if you don t want to use the antidither function 4 9 K Antidither scale Sets the scale factor or gain for the antidither function When the error is within the range specified by the J parameter the normal P and D gains will get scaled by the value of the K parameter This parameter is represented in 1 256 units meaning that if K 128 the three PID gains will be reduced to 50 128 256 0 5 when the error is within the antidither region set by the J parameter With K set to 192 the gains will be reduced to 75 and so on 192 256 0 75 It s perfectly valid
15. hip 2 2 Differences between the module and the UHU chip The module was designed to be pin compatible with v3 0 of the UHU chip With that said there are differences between the two and the following section of this document will try to cover the differences that need to be known before hand 2 2 1 Module pinout The following shows the actual pinout of the module Pin 1 Reset MCLR active low Pin 2 RXD data to module Pin 3 TXD data from module Pin 4 Not used not connected Pin 5 Not used not connected Pin 6 Step input Pin 7 Dir input Pin 8 Not used connected to high Z pin Pin 9 Not used connected to high Z pin Pin 10 GND Vss Pin 11 Not used not connected Pin 12 Encoder input A Pin 13 Encoder input B Pin 14 Fault input active low Pin 15 PWM output locked antiphase Pin 16 Enable output active high Pin 17 Fault output active low Pin 18 Firmware status LED see 2 2 1 Pin 19 Not used not connected Pin 20 5V Vcc Servo upgrade module userguide doc Copyright 2010 Page 5 of 30 2 2 2 Pins 4 amp 5 On the UHU chip pins 4 and 5 are used for the crystal oscillator The module features its own on board oscillator so these pins are not used nor connected to anything on the module You can safely leave the 24MHz crystal for the UHU chip on the servo drive PCB 2 2 0 Pins 8 amp 9 On the module pins 8 and 9 are connected to pins on the modules CPU which as of this wr
16. int Sets the allowed following error in encoder counts Please also see the F parameter E75 lt ENTER gt E Error limit 75 Setting the E parameter to anything above 32767 will effectively disable the trip limit all together Warning Setting the E parameter to very large values or disabling it completely can result in the internal calculations overflowing causing unexpected results like motor reversal and or runaway etc Be careful with this Generally a value of E equal to a couple degrees of motor shaft movement is considered a proper value 4 5 F Following error scale Sets the following error scale value This setting provides a way to scale the allowed following in relative to the currently commanded motor velocity That is the higher the commanded velocity is the larger following error is allowed without faulting F256 lt ENTER gt F Error scale 256 If you don t want to use this feature simply set it to 0 The following error trip limit you specify with the E command will then be what you get no matter what the commanded velocity is For more details about this setting please see Apendix B Servo upgrade module userguide doc Copyright 2010 Page 14 of 30 4 6 G Get parameter The G command is used in conjunction with a second letter to get various internal non changeable parameters and variables that can be useful during set up and tuning 4 6 1 GV
17. iting are not being used and are set to high impedance mode inputs In future firmware versions these pins may be used for other function which would then require rework of the servo drive PCB Several incarnations of the UHU based drives have pin 8 and pin 9 in parallell with pins 12 and 13 of the chip the encoder inputs This seems to come from earlier versions of the original chip while the documentation for v3 0 states that the encoder inputs are on pin 12 and 13 which is where they are on the module As long as your PCB is layed out to have the encoder signals on at least pins 12 and 13 it is OK to leave everything as it is If the encoder signals are available on pins 8 and 9 as well that won t be a problem with this version of the module 2 2 4 Pins 11 amp 18 These pins are not used nor connected to anything on the module 2 2 5 Firmware status LED The operation of the firmware status output differs from that on the original UHU chip On the original UHU chip this output was simply held at a constant low level LED ON when the chip was operating correctly On the module it blinks in certain patterns corresponding to the current state of the module Following error and external fault are two states that can easily be recognised by simply looking at the firmware status LED Normal state KA o TT Following error PALA A A A A e ia is Servo upgrade module userguide doc Copyright 2010 Page 7 of 30
18. k Olsson 2010 C Henri User Guide Rev A Servo processor upgrade module for UHU based drives Preliminary manual work in progress 2010 06 06 Table of Contents 1 ABOUT THIS SUIDE Ee ee eg A evra hy eN ge Ee Dee sd ve egg See ees EE 4 1 1 WHO SHOULDUSE EE RR EE ER OR IE ER ER ER N d 1 2 TYPOGRAPHICAL CONVENTIONS ees ee see ees ee ee see ee ee Ee ee ee Ee ee Re ee ee eek ee ee ee ee ee ee ee d 2 INTRODUCTION EES RE ee ER ed io 5 2 1 PURPOSE EERS DE e os PA eet htt total Occ Et Bi ae eo aos e EE aN oe ig 5 2 2 DIFFERENCES BETWEEN THE MODULE AND THE UHU CHIP eeuse ee ee ee ee ees ee ee ee ee ee ee ee ee ee ee ee ee ee ee 5 3 INSTALLING THE MODULE co acacia illa PR GROS Anne Ween DE PR EEN ee Ede SR EN ae Nege ee ed 9 3 1 SETTING UP THE TERMINAL SOFTWARE cccccssscecceceeseeeeceeesceccesusseeseesunseeceeaueeesesaueceessaneees 10 4 COMMAND REFERENCE spoon ee ees ees ee ee ee ee ee ee ee ee eee ee ee ee ee ee Ee ee ee ede ee ee ee ee ee ee ee 12 4 1 A ACCELERATION FEED FORWARD c 0scccsesccceeceeeeececececenecseueceeeseeecuececsueceeaeceseucessueeeneees 12 42 oo ORE ER RE OE EE EE eaten N 13 4 3 D DIFFERENTIAL GAIN SERS ee og E Pea bead Ub Sud doen ase HE es 13 4 4 E FOLLOWING ERROR LIMIT TRIP POINT eeue ee ees se ee ee ee ee ee ee ee ee ee ee ee ee RR ee ee ee ee ee ee ee ee ee ee 14 4 5 F FOLLOWING ERROR SCALE ie vein ave ee e ee Gee ee ee od ede ee eed a 14 4 6 6 GET PARAMETER Mad aa
19. le userguide doc Copyright 2010 Page 22 of 30 4 17 V Velocity feed forward gain The V command sets the gain for the velocity feed forward The velocity feed forward works by adding a scaled value of the commanded motor velocity to the final PWM output providing some extra push V750 lt ENTER gt Vi VEEL 7150 4 18 X Step multiplier The step multiplier can be used to gear up the speed based on the frequency of the incomming step pulses This can be useful when the step generating source has a limited top frequency while at the same time the motor is equipped with high resolution encoder For each incoming step pulse the internal setpoint register or target position is incremented or decremented depending on the direction signal by 1 Step multiplier setting counts The benefit of using a high resolution encoder even with a slow step signal source is that the higher resolution provides more information per shaft revolution for the PID loop to work with A very small displacement will get noticed and corrected while with a lower resolution encoder that same displacement may not result in even a single encoder count Warning Although it is possible to set the step multiplier to any integer value it s recommended to keep it below 10 In all cases should Step frequency Stepmultiplier 1220 be below 2500 You must also make sure that resulting encoder frequency is kept below 2 5Mhz
20. rs matching the 20 pin dual in line footprint of the original UHU chip Installing the module is a simple matter of removing the UHU chip and mounting the module in its place Depending on how your particular servo drive is designed it is possible that the servo processor module doesn t fit directly in place of the UHU chip as surrounding components may interfere with the larger footprint of the module If this is the case it s advisable to use one or more 20 pin dual in line IC sockets as raisers to get the module above the surrounding components Make sure to secure the module in case the stack is high using some hot melt glue RTV silicone or similar Here s a photo of the module mounted on the HP UHU drive e ge Age AU CSP Ss S N o n uw o Er hy Cc qa A Q Servo upgrade module userguide doc Copyright 2010 Page 9 of 30 3 1 Setting up the terminal software Here we will go thru how to set up Hyperterminal which comes with most versions of Windows to communicate with the module However any terminal emulating software capable of talking to a serial port should work To set up Hyperterminal start a new connection give it a name and click OK Select the appropriate COM port to which you connect your drive and click OK ps ag Y New Connection ey Servo Module Enter a name and choose an icon for the connection Enter details for the phone number that you want to dial
21. to it Assuming the L parameter being set for 1220Hz servo rate this means that at 2500rpm you ll get 2500 4000 60 1220 137 counts per servo update at full speed At stand still you want to have a trip limit of 10 counts 0 9 so you set the E parameter to 10 But at full soeed you may want to allow up to 50 counts 4 5 following error before faulting Calculating the value of the F parameter in this case is simply a matter of taking 50 10 137 256 75 How does it work At motor velocity 0 the trip limit is 10 at motor velocity 137 the trip limit is 10 137 75 256 50 counts At 1250rpm 50 the velocity in encoder counts second is 68 so the trip limit becomes 10 68 75 256 29 or half way between 10 and 50 If you set the F parameter to 0 the value of the E parameter is your following error trip limit at all motor velocities no scaling will be applied Servo upgrade module i Page 29 of userguide doc Copyright 2010 age 29 of 30 Document revision history 2010 06 06 First release of manual Servo upgrade module userguide doc Copyright 2010 Page 30 of 30
22. used to enter amp setup as well as to exit or abort the data recorder mode of the module To activate the data recorder mode send Z followed by a numerical value that is built up of the following three parts The sample rate the trigger source ie when to start recording and the source or data to be recorded Sample rate Trig source Data source Value 1 1 0 1 2 1 1 4 2 1 8 3 1 16 4 1 32 5 1 64 6 1 128 7 Vel cmd gt 0 0 Dir change cmd 8 N U 16 No Trig 24 Following error 0 Motor velocity 32 Velocity cmd 64 PID Output 96 PWM Output 128 Scaled limit 160 N U 192 N U 224 Sample rate is simply how often you want the module to record Maximum sample rate is whatever the servo loop frequency is set to see the L parameter If the L parameter is set to 4 for a servo loop frequency of 1800Hz selection the 1 16 sample rate will sample at 1800 16 112 5Hz The data buffer is 127 entries deep so sampling at 112Hz means 1 1seconds will fit in the buffer Servo upgrade module i Page 25 of userguide doc Copyright 2010 age 25 of 30 Choose one item in each column and add the values for each of them together Example To sample the PWM output at an rate of 1 32 starting on the next servo loop send Z157 lt ENTER gt 38Hz 5 No Trig 24 PWM Output 128
23. ush when accelerating and some extra pull when deccelerating A100 lt ENTER gt A A ff 100 Servo upgrade module userguide doc Copyright 2010 Page 12 of 30 4 2 C Clamp Sets the maximum PWM duty cycle This can be used to limit the effective voltage swing of the servo drive that the module is mounted to By default this is set to 760 which results in an effective output swing of 13 87 which is what the original UHU chip uses C500 lt ENTER gt C Max PWM 500 Internally a dutycycle of 50 resulting in a net current of OA is represented by the value 1024 0 would be 0 and 100 would be 2048 The value of C is simply the maximum amount that the duty cycle value is allowed to swing up or down from 1024 Example If you set C 400 the dutycyle will get clamped to 30 5 69 5 because 100 2048 1024 400 30 5 and 100 2048 1024 400 69 5 The maximum output swing of the module is 8 92 C 860 Setting C to a value higher than 860 is possible but will have no effect 4 3 D Differential gain Sets the differential gain of the PID loop D1100 lt ENTER gt D Kd 1100 900 The value shown within paranthesis is the gain that will be applied when the error is within the antidither region See the J parameter and the K parameter Servo upgrade module userguide doc Copyright 2010 Page 13 of 30 4 4 E Following error limit trip po
24. utput Offset 25 Warning Values above 32767 are treated as negative values two s compliment This means that accidently entering very large values can have undesireable effects Servo upgrade module userguide doc Copyright 2010 Page 20 of 30 4 12 P Proportional gain Sets the proportional gain of the PID filter P1250 lt ENTER gt P Kp 1250 1000 The value shown within paranthesis is the gain that will be applied when the error is within the antidither region See the J parameter and the K parameter 4 13 Q Quit servo This stops the internal execution of the servo loop sets the PWM duty cycle to 50 Offset and pulls the Enable output low effectively disabling the drive signals to the bridge drive circuitry on typical UHU based designs Removes power from the motor and freewheels it Q lt ENTER gt Servo is OFF Use the R command to re activate the module Even though the execution of the servo loop is suspended and the enable signal removed from the bridge drive circuitry the encoder is still being read and the position register updated 4 14 R Reset Restart This performs a soft reset of the module and restart of the servo loop Use this command to recover from a fault or to re enable the drive after it has been disabled with the Q command When the R command is executed the following happens internally e All internal error flags in the status register are cleared

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