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1. 2 1 General sarira eara ea REL 2 1 Communication Adapter Module 2 2 PTOCOSSO epu ah Geta eh ae oo eee 2 8 YO Chassis capiet aa ccc cece m 2 9 Power Supply sede te vor dor cd res Sas dee a doloe Re 2 10 Cables an CIT 2 13 Other Optional Equipment isses ere e RR ead eae 2 13 Chapter 2 13 Module Installation 3 1 General re a SG TOC OR Ge i Ra a 31 S WILCRI S ELUNGS os Armin na nice Sce ea RISK ER Me ORO p nenn ec RA 31 Sp au and una na are ern 3 7 Installation In Thel O Slot ces Ie 3 8 Cable Connections senene ccc na d an a rennen a G aa 3 9 COMMANGS 4 1 General san ane Renee ma Rav da da PA ERES 4 1 Protected Unpret id o cis vicem na ea hari aora ane a De EC bets 4 3 Write Commands sceau nes ex xor Rp CERE dE 4 4 Bit Write Commands 4 5 Read Command eek m eyed kenne 4 7 Accessible Data Table Locations PLC 2 Processors 4 7 Accessible Data Table Locations PLC 5015 4 9 Accessible Data Table Locations PLC 3 Processors 4 10 Accessible Data Table Locations PLC 4 Microtrol Processors 4 11 Chapter SUMMA ss i3 Chur Seite A arp PR RON REC te 4 15 Commu
2. Figure 10 1 Sample Program Start 011 077 015 02707 6 FIG FIG LI 000 000 000 OFF 013 141 146 02707 c G 16 1 000 000 000 03212 01200 160 030 037 02707 Fl Hess His C 000 000 000 02707 CU 11217 03312 03302 03212 L OFF 03202 11217 03212 1 II u H 03302 03312 f 03302 01000 f LI 03312 ar 03202 01000 r3 4 Uu Header Rung Memory Access Rung gt Communication Zone of Program Command Rungs Delimiter Rung Latch Start Bit Unlatch Start Bit Latch Output Indicator Unlatch Output Indicator 10 1 Chapter 10 Design Aids and Documentation Forms Memory Maps 10 2 The rungs used in this example illustrate the programming principles of chapters 5 through 7 of this manual Of course user application programming may vary widely from this example In any case certain types of support programming should be used in any program for a command at a station Support programming for each command includes START bit LATCH and UNLATCH control REMOTE LOCAL FAULT bit monitoring Each of these parts of the program is shown in Figure 10 1 Forms shown in Figure 10 7 to Figure 10 9 are available for programmer documentation Switch settings Communication Adapter Module cat no 1771 K A2 form 5030 Command Listing From station form 5032 Command Listing To station form 5033 These forms should be a part of
3. 8 5 Chapter SUMMEN aus ac mex ARE RAT ken 8 9 Start up and Troubleshooting 9 1 fl RP T 9 1 Start up and Troubleshooting 5 9 1 Startup Procedures anne are hu aa ee y 9 12 Traubleshoeind ia vsus Muse Rara ea a bios eis 9 18 Chapter SUmlfiBly as aus nah ad Ran a Ex RUE GR RES 9 23 Design Aids and Documentation 10 1 General aussah nahen 10 1 Program 5 2 us aan eR aan 10 1 POMS an a Med Weds ke 10 2 Memory Maps anne det acea true d 10 2 Error Code Listing uia i rx ae A 1 Description Chapter Introduction An Allen Bradley Data Highway extends the capabilities of programmable controllers by letting them exchange data with each other and with other intelligent RS 232 C devices Data Highway integrates individual controllers into a larger automated manufacturing network On a single Data Highway cable as many as 64 separate programmable controllers and computers can be connected over a distance of 10 000 feet 3 048m The unit that interfaces PLC 2 family programmable controllers to this network and makes communication possible is an A B Communication Adapter Module cat no 1771 K A2 See Figure 1 1 It is a Data Highway station interface module and is used with Bulletin 1772 programmable cont
4. Legend EEEEE SetbitEEEEE in remote station data table on FFFFF SetbitFFFFF in remote station data table off This format uses EXAMINE elements that address bits in the remote station processor These elements control remote station data table bits as follows EXAMINE ON This rung element instructs the remote station communication adapter module to turn the addressed bit on EXAMINE OFF This rung element instructs the remote station communication adapter module to turn the addressed bit off Program these elements immediately after the command code Any combination of these elements may make up this type of command rung Where necessary BRANCH START instructions and a BRANCH END instruction can be used to fit these elements into the display area of the programming terminal For practical reasons do not exceed this display area Multiple rungs of this type can be used as necessary Delimiter Rung The delimiter rung ends the communication zone of program With PLC 2 family processors this rung always has the format shown in Figure 5 8 5 11 Chapter 5 Communication Zone Rungs Figure 5 8 Delimiter Rung Chapter Summary 5 12 Chapter 5 was the RUNG chapter it discussed Communication zone rungs Communication zone of program Header rungs Memory access rungs Command rungs Start bit command code and word command format Bit command format with EXAMINE ON EXAMIN
5. In write operations data words are written to a remote station from the local station data table For a write command the first GET element in the command rung lists a beginning address at the remote station Data is to be written into this word and succeeding words from the local station data table The second and third GET elements in this type of rung list starting and ending boundaries for the word or words to be written from the local station data table In a read operation data words are read from a remote station processor into the local station data table The first GET element in the unprotected read command rung lists the beginning address from which data is to be read Remote data table words are read in succession beginning with this address Words are read only into the area of the local data table bounded by the second and third GET elements in the rung Only one set of GET instructions as shown in Figure 5 6 can be programmed in a single command rung Bit Command Format When the command code specifies a protected bit write or unprotected bit write command use the format shown in Figure 5 7 Chapter 5 Communication Zone Rungs Figure 5 7 Bit Command Format Area May Contain Any Legal Combination Of These Instructions LAH HHH Start Command Bit Code N EEEEE FFFFF 66666 027 07 IE E 1 1 1 Branch Start S If Needed 1 Ob ilt E
6. The user program controls the START bit setting it ON to initiate command execution turning it OFF after command completion or after a fault is detected Normally the START bit is turned ON by a LATCH instruction OFF by an UNLATCH instruction The use of retentive LATCH UNLATCH instructions is best suited for the timing relationship of START DONE and FAULT bits and helps to keep programming simple and straightforward To LATCH the START bit the program examines application conditions These may include input output device data values or other information from the controlled process For the most part an application condition used to initiate a command is one of these general types The ON or OFF status of some I O device Transition of some I O device Timed condition To UNLATCH the START bit the program examines the response from the communication adapter module This response may be one of the following DONE bit REMOTE FAULT bit LOCAL FAULT bit Chapter 7 Command Initiation Execution and Monitoring Thus the rung used to UNLATCH the START bit examines these three possible responses in parallel branches of the ladder diagram program Section titled ON OFF Input Status Transition and Timed describe the most commonly used forms of START bit control Each section describes a different method for initiating command execution all examples show how the program uses both DONE and FAULT b
7. Command Communication Response Adapter Scan Time UL Wa Legend 4 Start bit turned on by the program Remote fault or local bit set on by the communication adapter module to indicate that a fault condition has been detected Start bit turned off by program Fault bit turned off by the communication adapter module after it senses that start bit has been turned off GREC 7 3 Chapter 7 Command Initiation Execution and Monitoring Controlling The Start Bit 74 Recall that the START bit is program controlled The REMOTE LOCAL FAULT bits meanwhile are controlled by the 1771 KA2 module The programmer must keep this relationship in mind when planning START bit control and FAULT bit monitoring in the ladder diagram program Note from Figure 7 2 that the FAULT bit once ON remains ON until the START bit is reset turned OFF Only after it has detected that the program controlled START bit is OFF does the communication adapter module then turn the FAULT bit OFF Note also that the DONE bit is not set ON in the event of a fault condition NOTE In the special case where the START bit is turned OFF by the program before the KA2 sets a DONE or FAULT bit attempts to send that command are terminated The LOCAL FAULT bit is pulsed ON for approximately 60 msec in this instance This type of situation may occur for example if some event is programmed to UNLATCH the START bit before command completion
8. 2 11 Power up 9 14 PROC 2 7 9 3 Processor 1 1 PROG 9 3 PROG indicator 2 7 Program panels 9 4 R RCVG 9 2 RCVG indicator 2 6 R DY 9 3 R DY indicator 2 6 REMOTE LOCAL 2 13 S Search functions 9 4 9 5 Specification Summary 2 8 SPECIFICATIONS operating 2 8 START Bit 9 15 START bit controlling 6 2 6 3 7 4 START bit controlling 6 1 Start up 9 1 9 12 Start up Data Highway 9 12 START DONE bit status 7 2 START DONE bit timing 7 2 START DONE word 6 2 Station paired stations 9 13 Station testing 9 13 Switch settings 3 1 3 2 3 5 3 6 Switches 2 7 Station numbers 3 5 T Test rungs 9 9 Testing Receiving station 9 18 Timeout preset value 7 14 Timeout user programmed 7 17 Troubleshooting 9 1 9 15 l 1 U Upload 8 7 8 8 9 1 Using two modules 3 4 5 3 X XMTG 2 6 9 2 2 Zone Control Logic ZCL area 5 1 9 10 Zone Control Logic ZCL areas 5 3 ALLEN B R AD LEY Allen Bradley has been helping its customers improve productivity and quality for 90 years AROCKWELLINTERNATIDNAL COMPANY A B designs manufactures and supports a broad range of control and automation products worldwide They include logic processors power and motion contro devices man machine interfaces and sensors Allen Bradley is a subsidiary of Rockwell International one of the world s leading technology companies With major offices worldwide Algeria Argen
9. Contention between master stations prevents message transmission A 2 Symbols transition bit 7 9 Empty 2 4 2 5 2 11 8 3 9 6 A Acknowledgement message 8 4 C Cable connections 3 9 Cable DH Processor 3 11 Cables 2 13 Chassis 2 9 Codes error A 1 Codes timeout preset 7 16 Commands Bit write 4 5 Comuter 8 5 Diagnostic 8 6 8 7 Privileged 4 2 8 6 Protected 4 3 Protected Unprotected 4 3 Read 4 7 Write 4 4 Communication Adapter Module KA2 1 1 Connections Data Highway Program Interface 2 4 D Data Highway 1 1 1 2 2 1 2 9 3 4 3 6 8 1 8 2 Baud rate switch assembly 3 6 Done bit 6 2 7 2 Download 3 3 8 7 Downloads 8 8 E Error cod storage word 5 4 Error code 6 4 6 5 1 Error code storage 6 4 Error code storage word 6 1 6 5 9 3 9 8 F Fault bits 6 1 6 3 7 1 7 3 7 4 7 10 7 12 9 7 Monitoring 7 10 7 11 Fault word REMOTE LOCAL 6 1 6 2 6 3 6 4 6 5 6 7 Floating master 8 1 8 9 FORCE ON function 9 7 I O chassis 2 9 Indicators 2 6 Industrial terminal 3 10 Industrial terminals 9 4 Input image table 4 8 4 9 Input status ON OFF 7 5 transition 7 7 Mastership 2 6 7 1 8 1 8 2 8 9 Memory access rungs 5 5 Memory maps 10 2 Message priority 8 4 Messages Command Acknowledge Reply 8 3 Module KA2 2 2 0 Optional equipment 2 13 P Polling 8 5 Power Supplies 2 12 Power supply 2 10
10. Priority command designation Automatic disconnection of faulted master Commands that can be sent by computer Central to the interaction of station interface modules is the concept of shared mastership the floating master With this arrangement no single station controls the Data Highway communication link at all times Instead each station vies for mastership based on its need to send messages The advantage of this arrangement is that Data Highway operation can continue even if one or more stations are unable to maintain communication Thus disconnection of a station or a fault at a station processor or communication adapter module does not disable communication between other operating stations This minimizes the need for redundancy in many applications 8 1 Chapter 8 Station Interfacing Mastership A Data Highway cable links as many as 64 stations Because this cable has a single pair of wires only one station can transmit at a ime When a station interface module gains control of this data link to transmit messages that station has mastership When one station interface module is master all other station interface modules assume a slave or receive mode This enables these stations to receive and acknowledge messages sent to them The relationship between the master station interface module and all other stations is shown in Figure 8 1 Figure 8 1 Master Station Functions All Master Other Statio
11. Command reply operation complete The processor based on the program acknowledges completion of the command reply operation transient condition since the communication adapter turns the DONE bit OFF in its next scan 7 2 Start Bit Remote or Local Fault Bit Done Bit On Off On Off On Off Chapter 7 Command Initiation Execution and Monitoring Faulty Operation Certain fault conditions can prevent normal reception and execution of commands by the receiving station To indicate the source of such fault conditions the KA2 controls REMOTE and LOCAL FAULT bits at the station processor In general the LOCAL FAULT bit indicates that the local station cannot confirm delivery of a command to the remote station The REMOTE FAULT bit on the other hand indicates that the intended receiving station communication adapter module has received the command message but is unable to execute the command at its station processor For a quick summary of the distinction between these FAULT types refer to Figure 6 3 The timing relationship of these FAULT bits in command execution is shown in Figure 7 2 In this example the command initiated at the setting of the START bit executed due to some fault condition The communication adapter module detecting this fault condition sets either a LOCAL or REMOTE FAULT bit Figure 7 2 START FAULT Bit Timing Faulted Operation b La
12. Execution and Monitoring Figure 7 3 Status Initiated Command Remote Local Input Fault Fault Start 11111 03312 03302 032 12 e E Done Input Start 03202 11111 03212 1 U Local Fault 03302 J E 1 E Remote Fault 03312 1 c In this example the first rung is programmed to LATCH the START bit when the input bit 11111 is ON provided that both FAULT bits are OFF The second rung is programmed to UNLATCH the START bit based on the response of the communication adapter module In normal operation the START bit is LATCHED by the input 11111 the FAULT bits initially are OFF This causes the command message to be formatted and sent Then when the command is completed the DONE bit is set ON by the communication adapter module Note that the input bit 11111 must also be OFF to UNLATCH the START bit in this example With this arrangement the command message is sent only once input 11111 must be turned OFF then ON again to execute this command a second time In normal operation the START bit after successful command completion remains ON until input 11111 goes OFF Recall from Figure 7 1 that the communication adapter module holds the DONE bit ON until after the START bit is turned OFF Should a fault condition prevent normal execution these rungs provide a programmed re try of the command A REMOTE or LOCAL FAULT bit resets the START bit in the second rung In
13. Refer to Figure 4 1 The write and read commands transfer word data between the data table of the local station processor and the data table of a remote station processor The bit write command controls ON OFF status of one or more memory bits at a remote station processor Figure 4 1 Module Command Summary Data Table at Data Table at Local Station Processor Remote Station Processor J WES SPV ELV SS SS Al Write ll S SS 16 Bit Words ml key Bit Write E Individual Bit y E Read re ET Rp 16 Bit Words T oM Jd nn u Tl Communication Adapter Module 4 1 Chapter 4 Commands Privileged Commands This chapter describes functions of these commands and their access to data table locations at station processors A KA2 module can also receive privileged commands from a computer or another intelligent RS 232 C device through a 1771 KE KF communication controller module These privileged commands and their functions briefly include Diagnostic counters reset resets to zero all diagnostic timers amp counters in the station interface module Diagnostic loop use to check integrity of transmission over communication link Diagnostic read reads up to 244 bytes of data from PROM or RAM of station interface module Diagnostic status reads a block of station information from station interface module re
14. When you connect two communication modules to your PLC 2 family processor forces may or may not be cleared during uploading Use the following cross reference to determine whether forces will be cleared Does uploading take place through a later revision 1771 KA2 module series A revision D or later Does uploading take place through a module directly connected to a 1770 T3 terminal X v forces are not cleared forces are cleared and terminal shows mode select menu forces are cleared and terminal shows mode select menu forces are cleared and terminal shows mode select menu This chapter dealt with interfacing and interaction of a 1771 KA2 with its station and other stations on a Data Highway This chapter covered Floating master format Mastership of a Data Highway Command and reply messages acknowledgements Message priority Data Highway link disconnects Commands from a computer on a Data Highway through a communication controller module 1771 KE KF Diagnostic command summary Chapter 9 discusses start up and troubleshooting monitoring and module replacement 8 9 General Start up and Troubleshooting Aids Chapter Start up and Troubleshooting This chapter outlines an approach to start up and troubleshooting procedures Necessarily exact procedures that would be followed vary from one application to the next However these guidelines provide a u
15. channel and module logic circuitry NOTE The PROGRAM INTERFACE connector need not connect to a programming terminal for the module to operate This connector serves as a programming terminal connection whenever such a device is needed for program entry editing or monitoring Processor Connector The lower connector of the module connects to the station PLC 2 20 or PLC 2 30 processor or Mini processor module Refer to Figure 2 1 and Figure 2 2 A Data Highway Processor cable described in section titled Cables is used for this connection Indicators There are 5 LED indicators on the front of the module as seen in Figure 2 5 These indicators are useful for monitoring module activity and for troubleshooting Three green indicators show module status during normal receiving and transmitting of messages Two red indicators show the status of module diagnostics 2 5 Chapter 2 Station Hardware 2 6 Figure 2 5 Module Indicators Transmitting XMTG Receiving RCVG O Message Ready RDY O Program Status PROG O O Processor Link PROC Status XMTG The green transmitting indicator turns on when the module is current master of the Data Highway When this indicator is on therefore the communication adapter module is transmitting messages on the Data Highway communication link o
16. for instance the local station is the one sending the command A remote station is any station that receives a command from the local station Figure 4 1 illustrates this terminology Each 1771 KA2 module command has a prefix either protected or unprotected This prefix denotes memory access of the command The distinction between these command types is Protected commands can access write into only specified data table areas The program in the receiving station processor controls these areas In that program a memory access rung determines which data table areas will accept protected write or protected bit write commands Rungs are described in chapter 5 The receiving station ignores protected commands that are not defined by the memory access rung Unprotected commands require no memory access rung and they can read or write into any addressable data table word in the receiving station processor The primary distinction between these commands is program restriction of memory access Switch selections can also be made on the module for write protection to enable disable execution of many of these commands Chapter 3 gives switch selections Figure 4 2 summarizes the distinction between protected and unprotected commands 4 3 Chapter 4 Commands Figure 4 2 Protected Unprotected Command Distinction A protected command can access command can 021 only specified access any
17. os 2 Dropline EA 7 Remove trunkline Trunkline med Segments then Trunkline connect them to 2 Segment each other Tee v connector is free Before After 9 22 Chapter 9 Start up and Troubleshooting Chapter Summary Procedures for start up and troubleshooting were discussed in this chapter It detailed General procedures Aids to start up and troubleshooting Significant indicators on the 1771 KA2 in troubleshooting Use of industrial terminals and panels in troubleshooting Search functions Status indication for program instructions FORCE ON function REMOTE LOCAL FAULT bits ERROR CODE storage words The START bit s role in start up and troubleshooting Start up procedures Paired testing of Data Highway stations Steps for testing sending station and setting START bit Monitoring FAULT bits Module replacement Station disconnection In chapter 10 you will read about organizing and writing a program for a KA 2 module program summarization forms and memory maps for PLC 2 family PCs 9 23 General Program Summary Chapter Design Aids and Documentation This chapter provides programmer aids to help in writing organizing and documenting a program for a communication adapter module Figure 10 1 is a sample program that incorporates both a communication zone and the support programming recommended for the single command programmed in this zone
18. 1 to 10 seconds Note that values listed provide nominal values that will vary with activity level in the KA2 Table 7 B Timeout Preset Codes Timeout Interval Sec Code m 011 012 013 014 015 016 017 020 021 022 Cc U FP UC mn c Chapter 7 Command Initiation Execution and Monitoring If it is necessary to use a value other than those provided in Table 7 B compute the 3 digit timeout preset code as follows 1 Select a timeout preset interval This interval must be at least one second For the purpose of computing the code label this number S EXAMPLE desired interval 7 seconds S 2 Compute a decimal base 10 number using the desired interval of step 1 in the following formula S48 EXAMPLE 85 8 15 3 Convert this value to a 3 digit octal base 8 value EXAMPLE 15 602 178 For a brief description of decimal to octal conversion refer to chapter 13 of publication 1772 821 Programming and Operations Manual Mini PLC 2 Programmable Controller You can disable the timeout by using the value 010 User Programmed Timeout Optional The automatic timeout of a 1771 KA2 communication adapter module has a backup function This automatic monitoring routine continuously checks module interaction with other Data Highway stations timing the execution of commands This automatic timeout does not check module communication with its own station processor For a backup
19. A write command can control data table words at any station processor However certain data table areas at each type of processor have a special function and should not be controlled by write commands Sections titled Accessible Data Table Locations PLC 2 Processors and Accessible Data Table Locations PLC Processors cover data table control Bit write commands control the ON OFF status of bits in a remote station data table Unlike read or write commands bit write commands do not transfer data table memory data Instead the programmed command rung itself specifies which bits are to be set on or off when the command is executed Refer to chapter 5 There are 2 types of bit write commands that can be sent from a communication adapter module Protected bit write Unprotected bit write The distinction between these commands is their memory access Protected bit write commands are not executed by the receiving station unless a memory access rung defining the appropriate memory area is programmed at that station and switch is set Because this write protection feature allows added control over command execution use of protected commands is recommended A bit write command can control data table areas at any station processor However certain data table words at each type of processor have a special function and should not be controlled by bit write commands Data table control is the subject of sections titled Accessi
20. Data Highway testing limit the size of the group of stations being tested Initially start up testing is done with only 2 stations communicating at a time all other stations are OFF Then after each station has been tested in this manner the testing of more than 2 stations at a time can begin Finally after comprehensive testing of all stations station processors can begin normal operation To begin one station is selected as a starting point For the purpose of this description this station is labeled A Any station to which station A sends a command can then be selected as station B The first testing is then carried out between stations A and B with all other station interface modules disconnected Each command from A to B is tested and monitored to verify proper operation Then station B is checked for any commands that it received from station A and for any commands that it sends to station A Once testing between these two stations has been completed station B is disconnected and another station C is selected again based on its being addressed by a command from station A Since station A has already been tested for several functions problems with station C can be more readily located and corrected Paired testing continues in this manner until all commands programmed at station A have been tested Then commands from station B are tested with other stations This procedure continues with pairs of stations being tested each tim
21. Station Interfacing corresponding reply message The command code is described in chapter 5 Priority commands are executed ahead of normal commands throughout the command reply message cycle For this reason a command should be given priority designation only when special handling of specific data is required Using an excessive number of priority commands defeats the purpose of this feature and could delay or inhibit the transmission of normal messages When a station communication adapter module has a priority command or reply message ready for transmission the module responds to the next priority poll to gain mastership Polling No single station is permanent master of the Data Highway communication link Each station bids for mastership when it needs to send a message The station interface module at the current master station conducts a poll to select the next master station A poll is an orderly systematic method to determine which stations have messages to send and to select one of these stations as master The mechanics of the polling algorithm are essentially transparent to you This is because the communication modules handle this automatically However the polling algorithm does lead to the following basic rules that you should follow to optimize Data Highway performance Number your stations sequentially whenever possible and Keep the number of high priority messages as low as possible Large numbers of hig
22. addresses This means that PLC 3 input files with an 8 or 9 in their addresses are not used for read write access by a PLC PLC 2 station The only exception to these rules is that station number 000 is assigned input file I008 Accessible Data Table Locations PLC 4 Microtrol Processors Chapter 4 Commands The PLC PLC 2 station can use either protected or unprotected commands to access its assigned PLC 3 file Note however that the PLC PLC 2 station cannot access its assigned file until you create and allocate that file To create a PLC 3 file use the CREATE command described in the PLC 3 Programming Manual publication 1775 6 4 1 Programmable controllers can send the following non privileged commands to a 1773 KA interface module unprotected read unprotected write unprotected bit write protected write protected bit write A 1773 KA module accepts non privileged commands like other Data Highway interface modules with one exception the 1773 KA module does not have memory protection rungs Instead you set switches that allow or disallow the module to receive protected and unprotected commands The PLC 4 Microtrol controller uses a four digit address for its input output flags store timer and counter bits Timer and Counter status bits require an additional two digits When you issue a command from another programmable controller or computer do not enter these addresses instead enter an address code I
23. and indicators Specs of a 1771 KA2 Wherea KA2 resides and how it is connected to its station Optional equipment possibilities at a Data Highway station In chapter 3 you will read about KA2 switches and installation 2 13 General Switch Settings Chapter Module Installation This chapter outlines procedures for preparation installation and connection of a 1771 K A2 module Before performing these procedures you should check component compatibility and the station set up recommendations in chapter 2 There are 3 sets of switches a 1771 K A2 circuit board Write option switch assembly Station no switch group Data Highway baud rate switch assembly Refer to Figure 3 1 The switches at each station communication adapter module must be set as the programmer specifies To access these switches loosen the two screws that hold the small cover plate to the side of the module Then rotate this cover plate to expose the switches Figure 3 1 Module Switches La Ln La 2 F 2 f ma 0123456 01 2 01 2 3 01 2 3 01 2 dien N N N Data Highway Switch Assembly 2 Baud Rate B E E E Switch Assembly A J Station Number Switch Group mE 3 1 Chapter 3 Module Installation Us
24. and the input words of controller 1 send one command to read the store area and a second command to read the input words 2 Do not address more than one controller at a time For example if you want to read the store area of both controller 1 and controller 2 send two separate read commands 3 Do not send a command to a controller that is in program mode controller in program mode is not an active member of the loop because its data table is not being updated Chapter 4 Commands Chapter Summary This chapter told you about the 1771 KA2 s Station terminology Commands protected and unprotected reads amp writes Processors input image table addresses locations In chapter 5 you will learn about rungs codes and more commands 4 15 General Chapter Communication Zone Rungs At the beginning of the ladder diagram program you enter a special set of rungs that dictate communication adapter module activity The KA2 scans this set of rungs at power up for operating information WARNING Do not make on line edits of the communication zone Since the module scans the communication zone only when it powers up or when the processor changes state from program to run the changes will not affect module operation until you cycle power to the 1771 KA2 module or change the operating mode of the processor Attempting such edits may cause unexpected communication on the Data Highway Communication zone run
25. be connected to a Data Highway with power off A powered up module that is disconnected from the Data Highway will be in the polling state and cause a highway fault if it is re connected This is the same as connecting two active highway segments which also should not be done Data Highway Connection The module connects to the Data Highway communication link by means of a user assembled dropline This dropline connects to the trunkline of the Data Highway at a 1770 SC station connector Figure 3 6 or a 1770 XG tee connector 3 9 Chapter 3 Module Installation Figure 3 6 Data Highway Cable Connection Trunkline 1770 SC Station Connector C ee Dropline 100 feet maximum zb fe 5 LLLI Communication Adapter Module cat no 1771 KA2 Program Panel Interconnect Cable Connection The center connector of the communication adapter module is labeled PROGRAM INTERFACE When the module is installed and connected to the processor this socket connects an industrial terminal system cat no 1770 T1 T3 To connect with any of these terminals use the program panel interconnect cable cat no 1772 TC Figure 3 7 shows the programming terminal connections to the communication adapter module When an industrial terminal is connected this way you can perform all terminal functions except cassette loads or dumps You must disconnect the KA2 perform t
26. bit write command address only bits within a byte that is set aside exclusively for control by these commands The unprotected read command transfers word data from a remote station processor to the local station data table A single unprotected read command can access from 1 to 122 consecutive data table words The unprotected read command is not restricted by user programming This command can read data table words from any remote station processor regardless of either memory access rung programming or module switch settings Because this command controls data table words at its local station processor the rules for data table control apply when using this command Data table control is the subject of sections titled Accessible Data Table Locations PLC 2 Processors and Accessible Data Table Locations PLC Processor When it executes a read write or bit write command the communication adapter module controls data table locations at a station processor This section outlines the recommendations for control of data table locations in PLC 2 family processors A KA2 module executes read write or bit write commands to control any accessible data table words in any of these processors It also controls user selected status words in the data table of these processors Status words are described in chapter 6 A KA2 can access most data table words However certain memory areas in these processors have special functions that prevent
27. control of these areas by the module The following are data table areas with a special function in these processors 4 Chapter 4 Commands 4 8 Processor work areas Input image table Word 027 Later paragraphs describe the limitations in controlling each of these areas Access to all other data table areas is subject to the requirements of the programmer Processor Work Areas The processor work areas for PLC 2 family processors are addresses 000 007 and 100 107 These areas are used for specific processor functions and are not accessible to commands from a station communication adapter module The processor prevents an attempt to write data into this area from a remote station KA2 Note also that an attempt to read data from this area causes all 0 s to be read Only privileged commands from a computer can write into or read from this area of the data table Input Image Table The input image table areas for these processors are addressed as follows PLC 2 processor 110 127 PLC 2 30 processor 110 177 PLC 2 20 processor 110 177 Mini PLC 2 processor module 110 117 Mini PLC 2 05 processor 110 117 Mini PLC 2 15 processor 110 117 Please see appropriate processor manuals Table 1 B for details This area of memory is updated each input scan Any data written into it will be cleared on the next input scan This limits use of the input image table as a storage area for values or bits Note ho
28. for any station processor may vary significantly from those shown in Figure 5 1 The length of this program area is a function of the number of remote stations processors with which the local station processor communicates and the number of transmissions of data with these remote stations Figure 5 1 Communication Zone Format general Start Header 011 07 015 02707 Rund 6 1 16 1 16 1 OFF 020 070 076 017 02 02 02707 Wemay Te Ile 1 16 17 16 1 6 1 161 C Access Rung 017 063 065 010 060 062 16 16 Fco 16 FIG Command Rungs 03210 02000 016 022 024 02707 Read 1 lt iG HiG HIG Write Bit 03211 01702 12000 12001 12002 12003 02707 Wi El Et 12004 12005 12006 12007 EJ tat EA 12010 12011 13511 12600 Frm E amp 02707 Delimiter CU Run pu Header and delimiter rungs required for each station processor Memory access and command rungs 5 2 are programmed as needed Header Rungs Chapter 5 Communication Zone Rungs The order of these communication zone rungs is as follows 1 Header rung 2 Memory access rung s as needed 3 Command rung s as needed 4 Delimiter rung These rungs must always appear in this order at the beginning of the ladder diagram program If you are using two KA2 modules or a combination of KA2 and KG modules with the same processor enter one immediately after the other As a minimum requirement each st
29. not Chapter 7 Command Initiation Execution and Monitoring executed but also point to the general type of fault condition that prevented command completion The user program must monitor the REMOTE and LOCAL FAULT bits for each command The recommendations of this section describe two methods for monitoring FAULT bits and using these bits to signal a fault condition Diagnostic FAULT Rungs The purpose of monitoring REMOTE LOCAL FAULT bits is to control one or more output indicators to signal a fault condition Fault indicators controlled for this purpose may be as simple as a warning light or an annunciator or as complex as a line printer or CRT terminal used to display a fault message By controlling the fault indicator device the user program can alert user personnel to the nature and location of a fault condition To monitor the REMOTE and LOCAL FAULT bits a programmer must understand their timing relationship to the corresponding START bit Figure 7 2 summarizes this relationship The section titled Controlling the Start Bit showed how the FAULT bit can be programmed to UNLATCH the START bit in a fault situation and thus provide automatic re tries through the program When used in this manner however a FAULT bit will be rapidly cycled ON and OFF if a fault is detected Because the fault bit can be constantly changing state at a rapid rate the program must use some method of detecting this transient state of any
30. of status indicator On this terminal an LED indicator is labeled STATUS When the displayed instruction is logically TRUE this STATUS indicator illuminates Again this STATUS indicator is provided in both RUN and TEST modes The status indication is useful in monitoring the ON OFF status of START DONE and REMOTE LOCAL FAULT bits Chapter 9 Start up and Troubleshooting FORCE ON Function The FORCE ON function available with each of the 3 programming terminals can be a useful troubleshooting tool When used in conjunction with the optional test rungs of section titled Test Rungs Optional this function controls the initiation of each command programmed at a station An advantage of this programming terminal function is that it can be used only when the programming terminal is connected to the processor or in this case to the PROGRAM INTERFACE socket of the communication adapter module When the programming terminal is disconnected the FORCE function is removed A FORCE function can be entered in either the TEST or RUN mode On the industrial terminal and the PLC program panel the cursor must point to the instruction for a FORCE function to be entered On the PLC 2 program panel an instruction must be displayed for a FORCE function to be entered On the industrial terminal use the following key sequence for the FORCE ON function To initiate FORCE ON INSERT To remove FORCE ON REMOVE REMOTE LOCAL FAUL
31. of the ladder diagram program in the station processor Completed forms giving the following information Communication adapter module switch settings Listing of commands sent by the station Listing of commands received by the station 9 11 Chapter 9 Start up and Troubleshooting Start up Procedures 9 12 A ladder diagram printout can be generated on a compatible data terminal such as a teletype or other line printer Forms for programmer documentation are described in chapter 10 A careful start up procedure is essential to proper Data Highway operation With a methodical start up procedure cabling connections module set up and support programming for module communication can be tested at each station Start up of a newly installed Data Highway requires the combined efforts of maintenance personnel the programmable controller programmer and in many cases the computer programmer Because applications may vary widely the recommendations in this section are general Specific start up procedures will depend on the exact nature of the individual application For the procedures in this chapter the following preparation is assumed Station assembled using compatible components as described in chapter 2 Communication adapter module properly installed as described in chapter 3 Programming at the station processor includes the communication zone and the necessary support programming for initiating and m
32. preset value of this programmed TON instruction is not critical For this type of backup monitoring the programmed preset must exceed the timeout preset interval entered as a code in the header rung Remember that the automatic timeout of the module gives a LOCAL FAULT response to a command which would indicate normal module processor communication but faulted communication with some other station As with automatic timeout preset monitoring a user programmed timeout is useful as a backup to the other monitoring functions of the 7 18 Chapter Summary Chapter 7 Command Initiation Execution and Monitoring communication adapter module REMOTE and LOCAL FAULT bits at other stations indicate the same types of faults that can be detected using a user programmed timeout A programmed timeout would not be necessary for each command from a station Instead a single command at each station can be monitored in this manner Select a command that is sent regularly for this type of monitoring There may be other instances where program monitoring of commands is useful In some cases a user programmed timeout may be used to monitor the execution time of critical commands An application may require that a critical message such as a priority command be sent within a certain limited amount of time A programmed TON instruction can be used for this purpose here however its preset interval will generally be shorter than the interval ent
33. related fault either between stations or between the remote station communication adapter module and its station processor Figure 6 2 summarizes the significance of these bits Figure 6 2 REMOTE LOCAL FAULT Bit Significance Processor Local Fault i Possible Sources e e Disconnected data highway cable m Power off at receiving station a interface module B Unused remote staiton no address Al e Station interface moduel at local 4 or remote station has disconnected SSF itself as a result of link monitoring B Automatic timeout at sending e station fa Sending _ Station P Remote Fault Possible Sources sso Processor jj 0 U nl Remote station processor in program load or prog mode Command not executed due to module switch setting at receiving station Fault at remote station processor Power off at remote station processor Disconnected data highway processor cable p Error detected in communication zone of P loe e e program at remote station proccessor Receiving Remote Station 10866 1 6 3 Chapter 6 Status Words 6 4 REMOTE FAULT bits in the upper byt
34. the Data Highway communication link Figure 3 4 Data Highway Baud Rate Switch Assembly Both switches ON for 57 6K Baud Rate Keying Chapter 3 Module Installation The module is shipped with these switches set for 57 6K baud Both switches are set ON for this communication rate This baud rate is the intended Data Highway communication rate CAUTION Do not set these switches for any other baud rate Incorrect setting of these switches may cause faulted data transmission on the Data Highway communication link This may disable Data Highway operation until the switch setting is corrected After rechecking all switch settings replace the cover plate on the module The I O slot designated for the 1771 K A2 communication adapter module should be keyed to admit only that module Plastic keying bands shipped with the I O chassis accomplish this purpose These keying bands provide for only one type of module in a slot On the rear edge of the communication adapter module are 2 slots Position the keying bands on the backplane connector to align with these slots For the communication adapter module position keying bands on the upper backplane connector between these numbers printed on the backplane 4and6 22 and 24 Refer to Figure 3 5 Use needle nose pliers to insert or remove keying bands 3 7 Chapter 3 Module Installation Figure 3 5
35. the command and prepares a reply message A reply message is sent for each type of command The remote station communication adapter module responds to a poll for mastership then transmits its reply message to the local sending station Refer to chapter 8 for a description of mastership and polling When the local station communication adapter module receives the reply it sets the done bit on at the local station processor The DONE bit in turn is examined in the user program to turn OFF the START bit After the START bit has been turned OFF unlatched the communication adapter module resets the DONE bit 7 1 Chapter 7 Command Initiation Execution and Monitoring Figure 7 1 shows the timing of START and DONE bits for a command The significance of START DONE bit status is summarized in Table 7 A Figure 7 1 START DONE Bit Timing Normal Operation 2 5 vl E gt Processor Communication Command Scan Adapter Scan bs Response Done y Bit T Legend Start bit turned on by the program Done bit set on by the 1771 KA2 communication adapter module to indicate that a command has been completed 5 Start bit turned off by the program Done bit set off by the 1771 KA2 communication adapter module after it senses thatthe start bit has been set off 9 Table 7 A START DONE Bit Status Significance Idle Command initiated or in progress
36. turns ON when the module is current master of the Data Highway As described in chapter 8 mastership means that the module is sending messages on the Data Highway communication link This may be a command reply or polling message RCVG The green receiving indicator labeled RCVG turns ON when the module is receiving a message addressed to it When both this indicator and the XMTG indicator are ON the module is polling Chapter 9 Start up and Troubleshooting RDY The green message ready indicator labeled RDY turns ON when the module has messages that it is ready to transmit With this indicator on the module is ready to assume mastership when it is polled PROG The red program status indicator labeled PROG indicates the status of module checks on the communication zone rungs of program These rungs are described in chapter 5 A 1771 KA2 module checks the communication zone rungs of program at power up and whenever the mode select switch on the processor is turned from PROG to TEST or RUN It also checks these rungs after any received privileged write command is executed or whenever the Data Highway Processor cable is reconnected between the module and its station processor During this initializing procedure the PROG indicator turns on After the module has checked these communication zone rungs and if it has found no errors in programming format for these rungs the module turns the PROG indicator off However sho
37. 0 The following paragraphs describe settings for these switches RECEIVE PROTECTED COMMAND SWITCH Switch no 1 of the write options switch assembly determines whether the module is enabled to receive and execute protected write and bit write commands from other stations Set this switch as follows 32 Chapter 3 Module Installation ON Enables execution of received protected commands OFF Disables received protected commands Note that both an ON setting of this switch and a memory access rung are required to allow execution of received protected commands Memory Access rungs are described in chapter 5 This switch does not prevent the module from receiving and executing unprotected commands from another station A separate switch described subsequently enables or disables execution of received unprotected commands EXECUTE UNPROTECTED WRITE COMMANDS SWITCH Switch 2 determines whether the module can receive and execute unprotected write and bit write commands from other stations Set this switch as follows ON Enables received unprotected write and bit write commands to be executed OFF Disables the module from executing received unprotected write and bit write commands Note that this switch does not disable unprotected read commands from being received and executed by the module SHUTDOWN AUTOMATIC RESTART SWITCH On modules before revision D switch 3 presents the option after a hard error
38. 0 9 0 9 0 9 ERROR CODES be grouped as follows Codes 01 29 generally indicate that some programming error has been detected in the communication zone of program These codes are intended to indicate errors or processor communication faults detected at power up The program status indicator PROG may be on if one of these codes is displayed Codes 30 99 generally indicate that some programming or hardware related fault has been detected during attempts at communication between stations Codes 30 99 serve as diagnostic indicators after the initial power up checks of program have been completed A code in this 30 99 group is displayed whenever a REMOTE or LOCAL FAULT bit is set ON 6 5 Chapter 6 Status Words 6 6 The upper byte of the ERROR CODE storage word bits 10 17 stores a 2 digit BCD value This value gives supplemental error or fault information depending on the type of ERROR CODE displayed It may have one of two meanings a Reference number a Counter For ERROR CODES 01 29 the upper byte stores a 2 digit reference number This number points to the location of a programming error within the communication zone of program This error may be an incorrect instruction or an improper address entered within a rung of the communication zone In this numbering scheme the header rung of the communication zone of program is designated as 00 Subsequent communication zone rungs are numbered sequential
39. 077 17 Shipped 100 00 or 73 8 ree na Default Data Table 10 00 Expanded Image Tab M mage Table i 88 16 g 127 17 Additional Inputs 130 00 256 or Timer Counter Words Preset Values PR 104 16 Or Bit Word Storage 147 00 1 0 Timer C ounter 9 a Preset Values PR Or Bit Word Storage Y 128 24 17 17 Timer Counter 200 00 Accumulated Values AC Y 12 6 Or Storage 277 17 Timer Counter 300r 00 Preset Values PR Or Storage Y 256 64 37 1 User Program instructions 2048 1792 User Program 4096 2048 Instructions User Program 6144 2048 Pa Instructions P d User Program Instructions 8192 2048 Messages 10 3 Chapter 10 Design Aids and Documentation Figure 10 3 Mini PLC 2 15 Memory Organization i Word Bit Total pou Address Address Decimal Per Words Area 000 00 Processor Work Area No 1 e 8 007 1 010 00 Output Image Table Y 18 E Quy 020 00 Bit Word Storage 2026 17 24 8 Reserved o _ Timer Count 030 00 imer Counter Ve 7 e or Bit Word Storage NN aon e 100 00 Can be P Area P s 0 12 8 0107 17 110 00 Input Image Table Y is 8 120 00 Bit Word St Storage El B er 8 127 17 130 00 Timer Counter 7 Preset Values PR Z or Bit Word Storage Y 128 40 177 17 200 00 Expanded Data Table ri and or User Program Y an 1320 End of Memory 3777 May not be used for accumulated values Not avail
40. 1 No 2 No 1 No 2 No 3 OFF OFF 0 OFF OFF OFF 0 OFF ON 1 OFF OFF ON 1 ON OFF 2 OFF ON OFF 2 ON ON 3 OFF ON ON 3 ON OFF OFF 4 a First Digit ON OFF ON 5 ON ON OFF 6 ON ON ON 7 b Second and Third Digits 12331 3 5 Chapter 3 Module Installation 3 6 In this binary coded octal numbering arrangement each switch has an associated binary value 1 2 or 4 if set ON 0 if set OFF The value of each individual digit of the station number is the sum of the binary values in its corresponding switch assembly Table 3 A gives an example for the settings of this switch group Table 3 A Switch Setting Example Station No 037 STATION NO DIGITS SWITCH NO SWITCH SETTING Note that the switches allow a range of station numbers from 000g to 377g 256 possible numbers However there are practical reasons for using the the range 010g 077g and 110g 376g These station numbers are addressable from any station using an industrial terminal PLC 2 family programmable controllers cannot address 000g to 007g or 100g to 107g Also station 377g is an illegal address on the Data Highway To optimize response times use consecutive station numbers beginning with 010g Data Highway Baud Rate Switch Assembly The switch assembly labeled SW5 on the module circuit board is the data highway baud rate switch assembly Refer to Figure 3 4 The switches in this assembly must be set for the baud rate being used on
41. 306 033 05 03304 03303 03302 03301 033 00 055 00 IF A IFA 1 9 1 9 IFA 1 Remote Fault Rung 2 Status 03317 03316 03315 03314 03313 03312 03311 03310 055 01 1 eH I a eee Rung 3 Local Fault Status 05500 030 IE TOF 4 0 1 PR 020 Remote Fault Status 055 01 AC 000 IH JAL Rung 4 T naicator b E 010 00 This example shows the FAULT bit monitoring for 8 commands The 8 LOCAL FAULT bits are monitored in rung 1 As long as all 8 bits are OFF status bit 05500 remains ON However should any LOCAL FAULT bit be ON status bit 05500 is de energized In rung 2 the 8 REMOTE FAULT bits are monitored in the same manner to control status bit 05501 The status bits controlled by rungs 1 and 2 are in turn used to control an OFF DELAY timer in rung 3 The OFF DELAY timer begins to time when either of the status bits goes from OFF to ON that is when rung conditions go from TRUE to FALSE Bit 03015 the timed bit of the timer controls the output indicator As soon as the conditions of the timer in rung 3 are TRUE this bit is set ON causing the indicator to be energized Once ON this bit remains on as long as the timer is timing that is for at least as long as the preset interval In the example of Figure 7 7 this preset is set at 2 seconds This value is not critical but should exceed 0 5 seconds for practical purposes 7 13 Chapter 7 Command Initiation Execution and Monitoring Timeout Pres
42. 8064 Expansion 1000 words maximum 640 128 3 1177 1200 User Program Storage 027 Bits in this word are used User Program Begins by the processor for battery After End of Last low condition message Data Table Expansion generation and data highway 125 and 126 These words are used to indicate remote rack End of Program fault status a remote 1 0 system Report generation messages Unis Message Storage can be stored in memory 8192 17717 locations not used by data table or user program 10 5 Chapter 10 Design Aids and Documentation Figure 10 5 Mini PLC 2 Memory Organization Octal Decimal Words Address le Word 7 Total Decimal Words Used 17 116 115 114 13 112 11 110 07 06 05 04 03 02 01 00 000 00 Processor Work Area Y 8 8 No 1 00 17 0 0 0 0 1 1 1 0 1 0 0 1 1 0 0 0 010 00 16 Data Bit Word Output 16 8 Image Table 07 17 020 00 Bit Word Storage Y 026 17 24 8 Not Available for Word Storage 027 030 00 Timer Counter un or Bit Word Storage 64 40 07 17 100 00 DATA Processor Work Area TABLE No 2 72 8 107 17 110 00 Input Image Table 80 8 120 00 Bit Word Storage 88 8 p 17 130 00 Timer Counter ee PR 128 40 or Bit Word Storage 7 200 00 7 User Program A 512 384 End of Memory Optional second E Area 1024 512 Ba 10 6 To
43. Allen Bradley 1771 KA2 Communication Adapter Module User s Manual Important User Information Because of the variety of uses for the solid state equipment described herein and because of the differences between it and electromechanical equipment you must satisfy yourself as to its acceptability for each of your applications In no event will Allen Bradley Company be responsible or liable for indirect or consequential damages that may result from installation or use of this equipment The illustrations charts and layout examples shown in this manual are intended solely to help you understand the text not to guarantee operation Because of the many variables and requirements associated with any particular installation Allen Bradley Company will not assume responsibility for actual use based upon illustrations of applications No patent liability is assumed by Allen Bradley Company with respect to use of information circuits equipment or software described in this text Reproduction of any part of this manual without written permission of Allen Bradley Company is prohibited 1985 Allen Bradley Company PLC is a registered trademark of Allen Bradley Company Table of Contents INITOQUCHON ereignete 1 1 Description 11 About This Man al un cech RR EO CR ER E s 1 3 OTGANIZAUON EP 1 5 Chapter SUMMA rear 1 5 Station
44. DRESS ES 010 WRITE 023 025 TEMP VALUES REMOTE STATION SENDING COMMAND COMMAND DATA WRITTEN COMMENTS STATION NO TYPE TO ADDRESS ES 10 10 Chapter 10 Design Aids and Documentation We have tried to present information on the KA2 module in a way that will be most helpful to you Obviously we don t try to make errors and omissions but they crop up If you feel there s a way we could be of greater assistance please contact us at Allen Bradley Industrial Computer Group Publication Department 747 Alpha Drive Highland Heights Ohio 44143 Many thanks 10 11 Appendix Error Code Listing STS Byte of Reply Message Meaning in Hex No Error Processor communications problem May be processor fault No memory in communication adapter module for START bit file MEMORY ACCESS RUNG FORMAT First GET instruction incorrectly entered Invalid station number Second GET instruction incorrectly entered Third GET instruction incorrectly entered Third GET address less than second GET address improper access boundary definition Invalid end of access branch BRANCH END instruction must be inserted Invalid end of access rung Beginning of next rung invalid Refers to any rung after a memory access rung Or BRANCH START instruction missing COMMAND RUNG FORMAT START bit in lower byte START bit must be selected from upper
45. E OFF elements In chapter 6 you will read about bit storage fault words and error codes General Chapter Status Words A 1771 KA2 communication adapter module controls certain data table words specified in the local station processor by the programmer These data table words indicate the status of command execution and provide various types of diagnostic information for start up and troubleshooting These locations are or more pairs of adjacent words for START DONE and REMOTE LOCAL FAULT bit storage An ERROR CODE storage word Refer to Figure 6 1 The programmer specifies the locations of these status words when entering the communication zone rungs as described in chapter 5 Two START DONE and REMOTE LOCAL FAULT bit storage words are defined by selection of the START bit in a command rung You specify the ERROR CODE storage word in the header rung Figure 6 1 Adjacent Status Word Start Bit 03210 02707 A Command Rung Selection of Start Bit Automatically Desig nates Bits in Two Adjacent Words Start Bits Done Bits Word 032 i 2 i VW Ltt BN Program Communication Controlled Adapter Controlled mE Word 033 A 4 Remote Fault Bits Local Fault Bits UA Bits for Command Rung Shown B Start Done and Remote Local Fault Words 6 1 Chapter 6 S
46. ERNATIONAL COMPANY En ALLEN BRADLEY DATA HIGHWAY SWITCH SETTINGS COMMUNICATIONS ADAPTER MODULE CAT NO 1771 KA Publication 5030 October 1980 STATION NO INSTRUCTIONS USE APENCILTO NO 5 SEND DARKEN SWITCHES TO SHOW PROPER UNPROTECTED SETTINGS AS SHOWN KEEP THIS COMMANDS FORM WHERE IT CAN BE EASILY W ON ENABLED REFERENCED NO 2 RECEIVE W OFF DISABLED Dl EXAMPLE W ON ENABLED OFF W OFF DISABLED PROTECTED WON ENABLED W FIRST SECOND THIRD W Opra DISABLED Y Y DIGIT DIGIT DIGIT 0 1 2 O 1 2 3 0 1 2 3 01 2 N N N N 0 F F F F F F F ON 121 4121 14211 NO 3 UNUSED OFF olo 0100 00 0 MAY BE ON OR OFF BOTH ON FOR 57 6 BAUD RATE NO 4 RECEIVE SWITCH LOCATIONS PRIVILEGED WRITE W ON ENABLED W OFF DISABLED NO 6 PROCESSOR LINK BAUD RATE W ON PLC 2 20 PROCESSOR OR MINI PROCESSOR E COVER MODULE PLATE w OFF PLC 2 U PROCESSOR 2 B SWITCH Cmo LOCATION P 10 8 Chapter 10 Design Aids and Documentation Figure 10 8 Sample Form publication 5032 for Command Listing From Station ALLEN BRADLEY QQ ROCKWELL INTERNATIONAL COMPANY BY ALLEN BRADLEY DATA HI
47. FAULT bit and of controlling the output device based on this state Figure 7 6 shows a simple method for the control of a fault indicator Here either the REMOTE or LOCAL FAULT bit can LATCH the output indicator ON The indicator remains ON until the DONE bit is energized This then UNLATCHES the output indicator in the second rung of Figure 7 6 This example allows for the transience of the FAULT bits since the first rung need only be TRUE once for the output indicator to be latched 7 11 Chapter 7 Command Initiation Execution and Monitoring Figure 7 6 FAULT Bit Diagnostic Rungs Single Command Example Output Remote Fault Indicator 03310 01000 L OFF Local Fault 033 00 lL JL Output Done Indicator 03200 010 00 j E u The method of Figure 7 6 can be extended to monitor multiple commands from a station controlling multiple output indicators as necessary However where more than one command is being sent from a station the use of multiple output indicators may not be practical In this instance a single output indicator can be used to signal all REMOTE or LOCAL FAULT conditions for commands from that station Figure 7 7 shows a method for fault indicator control assuming multiple commands 7 12 Chapter 7 Command Initiation Execution and Monitoring Figure 7 7 FAULT Bit Diagnostic Rungs Multiple Commands Example Rung 1 Local Fault Status 03307 03
48. Fault Output Status Indicator 055 00 010 00 J F L OFF 05501 Instruction intensified Thus Local 1 Fault Status Bit 05500 is OFF Instruction normal intensity Thus this bitis ON d Local Fault Status 03200 03201 03202 03203 03204 03205 03206 03207 055 00 Ji 4 1 9 1 4 1 4 1911 o Start Command Bit Code 03112 02300 052 020 022 027 07 Hehehe Co 000 000 000 1 Using the SEARCH functions display the rung of program that controls the external FAULT indicator device Determine whether a status bit indicates that either a REMOTE or LOCAL FAULT bit is set ON 2 Using the SEARCH functions display the rung of program that examines either the REMOTE or the LOCAL FAULT bits and controls a status bit or bits based on FAULT bit states 3 Observe the individual instructions of this rung to detect any change in FAULT bit status When you use the rungs recommended in Figure 7 6 EXAMINE OFF instructions address each fault bit When these instructions are displayed 9 19 Chapter 9 Start up and Troubleshooting 9 20 on the program panel or industrial terminal observe the status indicators of the terminal carefully Due to CRT delay time the intensity of an EXAMINE OFF instruction which shows its status may not change as rapidly as does the actual ON OFF status of the FAULT bit Recall that programming re tries caused the FAULT bit to be continuously turned ON and OFE Thus it may
49. GHWAY COMMAND LISTING FROM STATION Publication 5032 October 1980 STATION NO EXAMPLE REMOTE AREAS CONTROLLED START COMMAND PRIORITY STATION NO COMMENTS ATLOCAL AT REMOTE BITS TYPE NORMAL ADDRESSED STATION STATION 04010 WRITE N 022 060 062 051 053 PARTS COUNT as REMOTE AREAS CONTROLLED START COMMAND PRIORITY STATION NO COMMENTS STATION m un NORMAL ATLOCAL AT REMOTE STATION STATION ENTER INFORMATION AS SHOWN START BIT DONE BIT Rue ADDRESSES STATUS WORDS 17 16 15 14 13 12 H 10 07 06 05 04 03 02 01 00 DARKEN USED START DONE ADJACENT Lan __ REMOTE LOCAL men REFERENCE ipd REMOTE FAULT LOCAL FAULT BITS BITS NOTE WHEN A START BIT IS SELECTED A DONE A REMOTE FAULT BIT AND A LOCAL ASSIGNED REFER TO USER S MANUAL COMMUNICATION 10 9 Chapter 10 Design Aids and Documentation Figure 10 9 Sample Form publication 5033 for Command Listing To Station ALLEN BRADLEY WINE AROCKWELLINTERNATIONAL COMPANY BY ALLEN BRADLEY DATA HIGHWAY COMMAND LISTING TO STATION Publication 5033 October 1980 STATION NO DIRECTIONS USE THIS FORM TO DOCUMENT COMMANDS RECEIVED AT THIS STATION FROM OTHER STATIONS EXAMPLE REMOTE STATION SENDING COMMAND COMMAND DATA WRITTEN COMMENTS STATION NO TYPE TO AD
50. However at the computer programmer s option privileged write commands can also be used to change data table values during a download of program Refer to publications 1771 6 5 8 and 1771 6 5 15 Diagnostic commands affect only the communication adapter module at a station not the station processor These commands access the read write memory of the communication adapter module They provide a check of module activity and permit computer control of specific aspects of communication adapter module behavior A summary of diagnostic commands and their functions is given in Table 8 A Chapter 8 Station Interfacing Table 8 A Diagnostic Command Summary Diagnostic loop Echoes transmitted data back in reply message Diagnostic read Copies up to 245 bytes of data from module memory Diagnostic counters Resets all diagnostic error counters n the module reset Diagnostic status Allows access to 28 bytes of processor and module status information Other commands are available for communication with other processors but will return an error code if sent to a PLC 2 family processor Indications of Upload Download Earlier revisions If you are using a revision of the 1771 K A2 module before revision D or a revision of the 1770 T3 terminal before revision G and are uploading or downloading the 1770 T3 terminal will display a mode select menu and a communication fault message clear all force instructions Later R
51. Keying Band Position N Ln 2 4 LAL 6 8 post 10 12 Keyin 14 Bands 18 20 26 28 30 J 32 34 36 Installation In The I O Slot Follow these procedures to install the module 1 Turn VO chassis power off This refers to the power supply that connects to the I O chassis at its backplane CAUTION To avoid module damage always be certain that power to the I O chassis is off before insertion or removal of the KA2 2 Insert the keying bands as described in section titled Keying 3 Insert the module into its designated slot Plastic tracks on the top and bottom of the slot guide the module into position Do not force the module into its backplane connectors Rather apply a firm even pressure to seat the module in its slot 4 Snap the plastic chassis latch over the module This secures the module firmly in the I O chassis 3 8 Cable Connections Chapter 3 Module Installation The following cable connections are made to a communication adapter module Data Highway cable Program panel interconnect cable cat no 1772 TC Data Highway Processor cable cat 1771 CR CO CN At set up all cable connections to the module can be made with power on After the program is up and running however it is safer to make connections with power off because of the possibility of noise that connecting will make Also again after the program is running a module should only
52. P LC 2 05 1772 830 1772 6 6 6 Assembly and Installation 1772 831 1772 6 8 6 Programming and Operations Mini PLC 2 15 1772 803 1772 6 6 1 Assembly and Installation Program Cont 1772 804 1774 6 8 2 Programming and Operations PLC 2 20 1772 807 1772 6 6 2 Assembly and Installation Program Cont 1772 802 1772 6 8 1 Programming and Operations PLC 2 30 1772 807 1772 6 6 2 Assembly and Installation Program Cont 1772 806 1772 6 8 3 Programming and Operations PLC 1774 812 1774 6 6 2 Assembly and Installation Program Cont 1774 800 1774 6 8 1 Programming and Operations PLC 3 1775 800 1775 6 7 1 Installation and Operations Program Cont 1775 801 1775 6 41 Programming PLC 4 Microtrol 1773 800 1773 6 5 1 Product Guide To use this manual 1772 6 5 1 knowledge of the particular progammable controller being used in your application is essential Because you connect the communication adapter module to an operating programmable controller you must have a good understanding of programmable controller operation installation memory structure and programming Publications are available for each Allen Bradley programmable controller All publications in Table 1 A and Table 1 B are available from an A B sales office or from Allen Bradley Publications 6100 Industrial Court Greendale WI 53129 Features of a 1772 KA2 Here are some of the KA2 s features New commands have been added to the 1771 K A2 that simplify upload and download p
53. Start 02000 03312 03302 03212 Rung 3 4191 1 L OFF Done Start 03202 03212 Rung 4 I U 4 Local Fault 03302 1 E J E Remote Fault 03312 Done Transition 03202 02000 Rung 5 I uU 1 7 8 Chapter 7 Command Initiation Execution and Monitoring In this example a storage bit called the transition bit is manipulated to control the sending of the command This bitis LATCHED whenever a transition of input 11111 is detected UNLATCHED only when the DONE bit is set ON A compare bit 01111 in this example is used to manipulate the transition bit In rung 2 the compare bit is controlled to match the ON OFF status of the input Because the input and the compare bit are programmed to have matching states both ON or both OFF the conditions of RUNG 1 can be TRUE only when the input has just changed from ON to OFF or from OFF to ON Thus rung 1 conditions set up a one shot TRUE only long enough to LATCH the transition bit Note that these rung conditions are FALSE as soon as the processor scans rung 2 The order of these rungs is important for this reason With the transition bit LATCHED the START bit in turn is LATCHED in rung 3 This initiates the command In normal operation the DONE bit UNLATCHES the START bit in rung 4 and then UNLATCHES the transition bit in rung 5 In faulted operation however rungs 3 and 4 repeatedly re try the command in much the same manner as in the example of Figu
54. T Bits The REMOTE and LOCAL FAULT bits provide the chief indicator of a hardware related fault that prevents normal communication As recommended in chapter 7 these bits must be programmed to control some output device to alert plant personnel of a fault condition When this output device signals a fault condition a programming terminal can then be used to display the ON OFF status of any REMOTE or LOCAL FAULT bit station processor Figure 9 3 summarizes the significance of both REMOTE FAULT bits 9 7 Chapter 9 Start up and Troubleshooting Processor Figure 9 3 REMOTE LOCAL FAULT Bit Significance Local Fault 1 Possible Sources e Disconnected data highway cable Power off at receiving station interface module Unused remote staiton no address Station interface moduel at local or remote station has disconnected po itself as a result of link monitoring Automatic timeout at sending station Sendin _ Staton D 7 Ga mane 1 DOC Remote Fault Possible Sources 530 Processor Remote station processor in program load or prog mode Command not executed due to module switch setting at receiving station Fault at remote station processor Power off at remote stat
55. WRITE 1 UNPROTECTED READ 2 PROTECTED BIT WRITE 3 UNPROTECTED WRITE 4 UNPROTECTED BIT WRITE After the command code the command rung then lists the memory areas affected by the command The format of this area varies based upon the type of memory area controlled by the command The length of the communication zone in PLC 2 family PCs is limited by the memory available inside the communication module Very few applications approach this limit but if you program too many command rungs the value 26 will appear in the error code word when you place the processor in RUN or RUN PROGRAM mode Each command rung ends with an OUTPUT ENERGIZE 02707 element This instruction is used solely for the purpose of fitting the command rung into the proper display format The output instruction of the command rung has no significance in program logic Examine START Bit Each command rung has a unique START bit in a memory word selected by the programmer Refer to section titled START DONE Word chapter 6 The START bits are examined by the communication adapter module When a START bit is on the communication adapter module carries out the programmed command Chapter 5 Communication Zone Rungs The START bit is controlled by the program This allows a command to be initiated only when necessary Programming methods for START bit control are given in chapter 7 Command Code The second element in a command rung the co
56. able for bit word storage Bits in this word are used by the processor for battery low condition message generation EPROM transfer and data highway Unused timer counter memory words can reduce data table size and increase user program area E May not be used for preset values Do not use word 127 for block transfer data storage 10 4 Chapter 10 Design Aids and Documentation Figure 10 4 PLC 2 30 Memory Organization Octal Total Decimal Word Address Decimal Words Words PerArea 000 Processor Work Area 8 8 Nod 007 Rack 1 010 017 010 Rack 020 027 Output Image Table Rack3 030 037 for a areas at are no Rack 4 040 047 configured as output Rack 5 050 057 table become available for Rack 6 060 067 accumulated values or 64 56 Rack 7 070 077 7 word bit storage Processor Work Area 100 72 8 No 2 107 Rack 1 110 117 110 Rack 2 120 127 Input Image Table Rack address areas Rack 3 130 137 that are not E configured as input Ba table become Rack 5 150 157 aval D for timer counter preset Rack 6 160 167 values or word bit 128 56 Rack 7 170 177 177 storage Timer Counter ACC Values or 200 Internal Storage 277 Timer Counter Preset Values or 300 256 128 Internal Storage 377 Expansion 100 Data table can be expanded 384 128 1 577 128 ph increments 600 unused sections are PATRE utilized for user program 512 128 111 storage to
57. also See A B PD sheet 1770 953 Replace the SC cover Figure 9 8 illustrates station connections with a 1770 SC connector and a tee connector 9 21 Chapter 9 Start up and Troubleshooting Figure 9 8 Disconnecting a Station Trunkline In Trunkline Out I 1 7 I 1 Cable Wiring 1770 SC O Station Connector Cable Blue Clear Shield Trunkline 1 3 2 o D Dropline 6 8 7 BE P S U lo x 15 Pin Connector Ground Wire Pin 6 Blue im Green Pin 7 Shield Pin 8 Clear to Earth Ground Dropline Cable B Notes To Data Highway Module BH Twist trunkline wires of same color before securing to screw clamp terminals 1 2 and 3 WA For dropline cable ten feet or less isolate the dropline shield from the enclosure El For dropline cables greater than ten feet attach the dropline drain wire to terminal 7 When the station is first or laston a trunkline attach a 150W resistor to terminals 1 and 3 Tee Connector Trunkline Segment Tee Connector me fd R OE n Ei 1 89 H HZ
58. ammable Controller Mini Computer 1220 The terms communication adapter module and 1771 K A2 and KA are interchanged throughout the manual Chapter 1 Introduction This manual describes installation operation and programming necessary to use the KA2 communication adapter module Use this manual with the other manuals and publications pertinent to your system Table 1 A lists other available Data Highway manuals and Table 1 B lists PC manuals Table 1 A Data Highway Documentation Old New Publication Publication Number Number 1774 819 1774 6 5 8 User s Manual Communication Adapter Module cat no 1771 KA 1771 822 1771 6 5 15 User s Manual Communication Controller Module cat no 1771 KE KF 1771 823 1771 6 5 16 User s Manual PROVOX system Interface Module cat no 1771 KX1 1773 801 1773 6 5 2 User s Manual PLC 4 Microtrol Communication Interface Module cat no 1773 KA 1775 802 1775 6 5 1 User s Manual Communication Adapter Module cat no 1775 KA 1771 81 1771 6 5 8 User s Manual PLC 2 Family RS 232 C Interface Module cat no 1771 KG 1770 810 1770 6 2 1 Data Highway Cable Installation Manual 1 3 Chapter 1 Introduction Table 1 B Manuals for Allen Bradley Programmable Controllers Old Controller Number Manual Tltle Mini PLC 2 1772 820 1772 6 6 3 Assembly and Installa Program Cont 1772 821 1772 6 8 4 Programming and Dua on Mini
59. an be done easily for each START bit at a station processor no special procedure for command initiation is necessary However it may not always be practical to simulate application conditions for the purpose of command testing In this case a special set of test rungs can be added at the end of the user program Using these rungs the programmer control command initiation directly from the programming terminal CAUTION Do not alter the application program for troubleshooting purposes This can cause undesired machine operation since the program may no longer operate as had been intended The optional test rungs described here are recommended with this caution in mind The specific format of these rungs allows control of commands without altering the main body of the application program Because these tests rungs are within a ZCL area the output instructions of these rungs are executed only under strict programmer controlled conditions and only when the programming terminal is connected Except where intentionally activated by the proper key sequence these rungs are ignored by program logic in normal operation 9 9 Chapter 9 Start up and Troubleshooting 9 10 Rung 1 Rung 2 Rung 3 Rung 4 Optional test rungs are shown in Figure 9 5 Within this ZCL area the START bit is unconditionally LATCHED ON rung 2 and UNLATCHED when the DONE bit is ON rung 3 In rung 1 a single input image table bit is the condition for t
60. area of data fable lt 022 gt areas determined memeory at a 023 by memory access receiving station f 2 rung in receiving processor station of memory Branch Start ae Instruction Table gt VA EM uo n 16 1 16 1 16 Access Definition b Memory Access Branch typical 10866 1 NOTE For most write and bit write operations between station processors protected commands should be used Because memory access must be allowed by the program at the receiving station processor protected commands allow programmed write protection which gives the programmer an added degree of control over command execution Unprotected commands provide the same functions in transferring data but without this write protection at the receiving station Write Commands A write command transfers word data from the local station processor to a remote station A single write command can send from 1 to 121 consecutive data table words There are 2 types of write commands that can be sent from a station communication adapter module Protected write Unprotected write The distinction between these types of commands is their memory access Protected write commands are not executed by the receiving station unless a memory access rung is programmed at that station and switch 1 on write options is set Because this allows added control over data transfer use of protected commands is recommended 4 4 Bit Write Commands Chapter 4 Commands
61. ation processor must have a header rung and a delimiter rung This provides the advantage of an ERROR CODE storage word controlled by the module as a diagnostic indicator If you are using two communication modules with the same processor possible with 1771 KA2 and 1771 KG series B modules only you must program a separate and complete communication zone for each module Modules must have different station numbers The figures in this chapter show 3 digit addresses above most GET instructions but not the 3 digit data value displayed below the GET symbol This convention is used for clarity since for the most part only the 3 digit GET address is significant when entering a program In entering communication zone rungs you needn t program any data into GET instructions A header rung as shown in Figure 5 2 indicates the beginning of the communication zone For the communication adapter module cat no 1771 KA2 the output position of this rung is always the LATCH 02707 instruction 5 3 Chapter 5 Communication Zone Rungs Figure 5 2 Header Rung Local Address of Timeout Station Error Code Preset Number Storage Word Code 011 077 015 02707 G 6 6 CL 000 000 000 OFF The 3 GET instructions in the header rung list the following Local station number Address of ERROR CODE storage word Timeout preset code The local station number is a 3 digit number switch selected on the 1771 KA2 module Th
62. ble Data Table Locations PLC 2 Processors and Accessible Data Table Locations PLC Processors On each 1771 KA2 communication adapter module the sending and receiving of write messages can be enabled or disabled by switch settings Refer to chapter 3 Bit Write Access The bit write command can be used to control any accessible data table bit However this command must not be used to control the following Any bit whose status is controlled by a programmed output instruction Any bit in a byte that also contains program controlled bits 4 5 Chapter 4 Commands This first restriction simply states that no bit should be directly controlled that is addressed by both an output instruction at its local station processor and a bit write command from some remote station processor Bit write commands are generally used to set storage bits in a station processor data table These storage bits may then be examined in the user program as conditions to energize an output bit This indirect programming technique allows control using bit write commands but helps to prevent the confusion that can result if an individual bit is controlled from both an OUTPUT ENERGIZE instruction and a bit write command Figure 4 3 gives an example of an indirect programming technique used to control bit 01001 which is addressed by an output instruction with a bit write command Here storage bit 12104 is controlled by the bit write command Th
63. byte bits 10 17 Second EXAMINE element incorrectly entered Invalid command code Invalid remote station number in command code Invalid element in bit write rung First GET incorrectly entered word command format Second GET incorrectly entered word command format Third GET incorrectly entered word command format End of rung incorrectly entered word command format Beginning of new command rung invalid or memory access rung programmed following command rung REMOTE LOCAL FAULT word not in data table START DONE word incorrectly chosen Unprotected command not allowed by switch setting at local station Same start bit used in more than one command rung Excessive number of command rungs more than 256 Timeout setting too large Valid timeout settings are 011 to 407 A setting of 010 disables the timeout Bad address in command rung Bad size in read write command 1 Appendix A Error Code Listing STS Byte of Reply Message in Hex COMMUNICATIONS ERRORS MAY BE DISPLAYED IN CONJUNCTION WITH REMOTE LOCAL FAULT BITS Processor memory discrepancy Controller communications problem May be processor fault Improper command message size Invalid command code Invalid station number Attempt to send unprotected command invalid Command execution aborted by sending station processor Command execution aborted Execution time exceeds timeout preset value Local processor entered the program mode Processor
64. ce in start up and troubleshooting Figure 9 1 shows the significance of various combinations of energized indicators Three green indicators show module status in normal message transfer Two red indicators show the status of module tests of the program and module communication with its station processor 9 1 Chapter 9 Start up and Troubleshooting 9 2 Figure 9 1 Module Indicator Combinations Ready to Station Address Transmitting a Receiving a Send is 377 Message Message Message Illegal i H m COMM comm Transmitting ADAPTER ADAPTER ADAPTER On Receiving On Off On Ready gt On Off Program Status Bot Flashing Processor Link Status Alternately coun coum coum coun com ADAPTER ADAPTER ADAPTER ADAPTER ADAPTER On On On OnorOff On On Both momentary continuous On Flashing Polling to Communication Program Processor Fault in Module Relinquish Zone of Fault in Communication Memory Circuitry Mastership Program Communication Fault Detected at Being Checked Zone Power up 12361 The following paragraphs describe each indicator and its significance to the troubleshooter XMTG The green transmitting indicator labeled XMTG
65. ch Controller Controller 5 V on Loop Controller 6 32 Flags V X101 X132 Controller 7 V Controller 8 5101 5199 Controller 1 s Stores Timer Counter 1 Value N 16 15 Controller 1 s N Counters Sy pes alue N13 31 S Timer Counter 32 Your Program N Sequencer Tables Each time you enter a non privileged command you must enter an address code This code designates what part of the controller s memory the command will affect Note that this is a code and not a true memory address A memory address code is a 3 4 digit code that represents a word 16 bits in the data table of a PLC 4 Microtrol controller The right most digit of an address code represents the controller ID number in octal For example 4 13 Chapter 4 Commands 4 14 address code 010 addresses the first controller controller 1 while address code 011 addresses the second controller controller 2 A PLC 4 Microtrol uses a decimal addressing scheme Table 4 A The PLC 2 family of programmable controllers use an octal addressing scheme Thus you must convert the PLC 4 Microtrol s decimal addresses to octal Address codes are divided into four sets 1 store words N input output and flag words Oe input output and flag area A timer counter words When using these address codes observe these restrictions 1 Do not address more than one set at a time For example if you want to read both the store
66. check on module processor communication an optional programmed ON DELAY timer instruction TON can be used With proper module processor communication the module sets either a DONE bit or a REMOTE or LOCAL FAULT bit as a response to a command However in the event of faulted module processor communication or faulted module operation a response bit might not be set Instead the START bit would remain on in this instance until the fault situation was corrected Several programming methods can be used 7 17 Chapter 7 Command Initiation Execution and Monitoring to detect such a condition the simplest of these methods uses an ON DELAY timer Figure 7 9 shows typical rungs that can be programmed for this purpose Figure 7 9 Typical User Programmed Timeout Start Done 03212 032 02 060 nes TON 0 1 Remote F ault n 03312 1 1 Local Fault 033 02 1 1 Output Timed Bit Indicator 060 15 01002 u E In the first rung of this figure timer 060 times the interval between the setting of the START bit for a command and the DONE LOCAL FAULT or REMOTE FAULT response of the module If no response is received within the preset interval of this timer here 10 seconds a fault may be indicated and bit 06015 set ON The second rung examines this bit to turn on a warning indicator Depending on the individual application this bit could also be used to enable or disable various parts of the program The
67. communications problem May be processor fault Invalid transparent word in reply message No communication zone rungs in program Reply not expected Reply received but START bitis OFF Processor memory not in format for communication Invalid reply Reply received but communication zone rungs are incorrectly entered Or reply received when processor mode select keylock switch is in the PROGRAM LOAD POSITION Program status indicator PROG may be ON to indicate this type of error condition May mean memory access rung missing for received protected command Incorrect sequence number in reply Refers to transparent word in message format Reply message is of incorrect size Illegal command Station processor communication problem Remote station processor faulted or OFF 1 0 fault at remote station processor Transmitted command disallowed by switch setting or memory access rung programming at remote station Transmitted command disallowed by switch setting at remote station Remote station processor in PROG or PROGRAM LOAD mode Communication zone invalid at remote station processor Program status indicator PROG may be ON atthat station Remote station communication adapter module unable to buffer received command in memory Remote station is in download mode or error in download command or operation not allowed in upload or download mode or operation not allowed when not in download mode Destination station fails to respond
68. dule cat no 1771 KA2 zi S S Data Highway Processor Cable cat no 1771 CR 12326 2 1 Chapter 2 Station Hardware Figure 2 2 Typical Station Configuration Mini PLC 2 Mini PLC 2 05 and Mini PLC 2 15 Controllers Data Highway Cable Trunkline y Station Mini Processor Module cat no 1772 LV LS LSP a 1772 LN1 LN2 LN3 U xdi System Power Supply Connection for n g Programming Terminal Communication Adapter Data Highway Module cat no 1771 KA Processor Cable cat no 1771 CN CO 12327 As these figures illustrate the term station combines both the communication adapter module and its connected programmable controller processor When specifying only the individual processor or communication adapter module at a station the terms station processor or station communication adapter module are used The following sections describe the functions and compatibility of each station hardware component Communication Adapter Module A communication adapter module cat no 1772 KA2 provides the interface between all PLC 2 family PCs and other stations on the Data Highway Refer to Figure 2 3 The module has sockets for cable 2 2 Chapter 2 Station Hardware connection switches for enabling or disabling specific module operations and indicators to aid in monitoring module behav
69. e KA2 module can communicate with as many as 63 other Data Highway stations Module transmitting and receiving circuitry on this channel are transformer coupled to the Data Highway link This design permits differential transmission of data with high common mode noise immunity Electrically transformer coupling provides isolation between module logic circuitry and the Data Highway cable Program Interface Connector The middle outlet on the module connects to an industrial terminal system cat 1770 T1 T3 or to a second KA2 or to a 1771 KG series B module 2 4 Chapter 2 Station Hardware To connect any programming terminal to the PROGRAM INTERFACE connector use a program panel interconnect cable cat no 1772 TC With a 1772 K A2 module installed the PROGRAM INTERFACE connector substitutes for the PROGRAM PANEL connector on PLC 2 20 or PLC 2 30 processors or the INTERFACE socket on the Mini PLC 2 Mini PLC 2 05 or Mini PLC 2 15 This means that all interaction between the processor and the programming terminal is controlled through the communication adapter module This interaction includes program entry and any functions that involve peripheral devices except cassette loads including report generation contact histograms and generation of program copies on paper or on punched tape The communication rate over this channel is 9600 baud Optical electrical isolation is provided between receiving circuitry on this
70. e application program that are affected by data transferred from the sending station To identify areas of the program that are affected by transferred data refer to Form 5033 which is recommended programmer documentation for each station 2 Observe that the data at these locations matches the data in the proper locations at the sending station processor For write or read commands observe instructions that address transferred words in the program at the receiving station processor These instructions include GET PUT TON TOF RTO CTU and CTD For bit write commands observe the ON OFF status indicator for instructions that examine those bits in the program The same tools and procedures used in start up of a station containing a communication adapter module can be used for troubleshooting This section outlines procedures that can be used in addition to the start up procedures of section titled Start up Procedures Chapter 9 Start up and Troubleshooting REMOTE LOCAL FAULT Indicator ON As recommended in chapter 7 some indicator must be controlled by the status of the REMOTE and LOCAL FAULT bits at each station processor Should this indicator go ON connect and initialize a programming terminal and follow these procedures to isolate the source of the fault condition The steps of this procedure are outlined in the example of Figure 9 7 Figure 9 7 REMOTE LOCAL FAULT Troubleshooting Example Local
71. e of this word A REMOTE FAULT bit is set ON when a command is received at a remote station but cannot be executed by the remote station This may mean one of the following Remote station processor has detected a fault in its own operation or has shut down Remote station processor has power OFF Remote station processor has mode select switch in PROGRAM LOAD or PROG mode Cable between remote station adapter and processor is disconnected or faulty Module switch setting prevents execution of the received command Error has been detected in communication zone of program at remote station processor PROG indicator may be ON A REMOTE FAUL bit indicates that the remote station communication adapter or controller module received a message but could not communicate with its station processor to execute that command LOCAL FAULT bits are in the lower byte of this word bits 00 07 A LOCAL FAULT bit is set when the local station cannot confirm delivery of the message to the remote station This may mean one of the following Automatic timeout of command completion by communication adapter module Disconnection of the local or remote station interface module from the Data Highway cable Loss of power to the remote station communication adapter module Unused station number addressed by the command Excessive noise along the Data Highway cable caused by other equipment in the industrial environment At the sam
72. e reason for selection of this bit Rung2 In the LATCH instruction enter the START bit address for the command being monitored Rung 3 Enter the address of the DONE bit for the EXAMINE ON instruction Enter the address of the START bit for the LATCH instruction Check that the format of these test rungs resembles the one shown in Figure 9 5 With these rungs entered a command can now be initiated To do this use the FORCE ON function of the programming terminal Perform the following steps 4 Turn the processor mode select switch to the TEST position 5 Position the cursor on the EXAMINE ON instruction of Rung 1 On the PLC 2 program panel display this instruction 6 On the programming terminal press the key sequence for the FORCE ON function With an industrial terminal press these keys FORCE ON INSERT With program panels press these keys SELECT FORCE ON INSERT The START bit is now LATCHED ON Under normal operation this bit is being LATCHED and UNLATCHED as the processor executes its scan and the command is sent continuously Chapter 9 Start up and Troubleshooting With the START bit energized proceed to the monitoring checks of the paragraph entitled Monitoring DONE and REMOTE LOCAL FAULT Bits Once these checks have been completed the next START DONE bit addresses can be entered in the test rung for testing of the next command The FORCE ON function can be removed using the prog
73. e the tip of a ball point or other pointed instrument to set these switches Do not use a pencil as lead could jam the switch For troubleshooting purposes we recommend that the programmer document the required switch settings for each 1771 KA2 Use form 5030 in chapter 10 to record switch settings for the module at each station That way should replacement of the module be required switches on the replacements can be set quickly Write Option Switch Assembly The first rocker switch assembly from the left is the write option switch assembly Refer to Figure 3 2 In this assembly switches numbered 1 through 5 enable or disable different types of write and bit write commands from being received by or sent from the communication adapter module Note that the unprotected read command is not affected by any of these switch settings Switch no 6 enables and disables daisy chain operation See FIRST SECOND MODULE at end of this section Figure 3 2 Write Option Switch Assembly Shutdown Auto Restart Execute Unprotected e On Shutdown Write Commands e Off Auto Restart Receive Protected Received Priviledged Commands Write O1 2 3 4 5 N N F i Enable Disable Send Unprotected e On First Module Commands e Off Second Module After revision D the name and function of switch changed to Execute download in RUN program 1233
74. e time it sets a REMOTE or LOCAL FAULT bit ON the KA2 enters a 2 digit ERROR CODE into the ERROR CODE storage word The ERROR CODE storage word is described in the following section By monitoring these bits in the program operators can be alerted to hardware conditions that prevent normal transmission and execution of commands Programming techniques for monitoring FAULT bits are described in chapter 7 Error Code Storage Word Chapter 6 Status Words When a command cannot be carried out due to a user programming error or a discrepancy in data handled by the communication adapter module an ERROR CODE may be written into a data table memory word The programmer selects the error code storage word and lists it in the header rung of the communication zone of program This word stores the most recent error code written by the KA2 Figure 6 3 shows the structure of the ERROR CODE storage word The lower byte of this word bits 00 07 stores any ERROR CODE entered by the module In this byte the ERROR CODE is represented as a 2 digit binary coded decimal BCD number from 00 99 Table A 1 Appendix A lists and describes these ERROR CODES Figure 6 3 ERROR CODE Word Format 2 Digit Value Reference Number Error Codes 00 99 for codes 01 26 in BCD Format Counter for codes 30 99 Refer to Table 6 A mii XE 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 9
75. e until all commands sent on the Data Highway have been checked in this manner By following this procedure you test each command for proper execution by the station interface modules at each station This testing also checks the support programming done at each station to initiate and monitor commands including REMOTE LOCAL FAULT monitoring The procedures of sections titled Testing the Sending Station and Testing the Receiving Station are used for paired testing of stations For a station sending a command carry out the procedures of section titled Testing the Sending Station At the receiving station carry out the procedures of section titled Start up Procedures 9 13 Chapter 9 Start up and Troubleshooting 9 14 Increasing the Group Size Once paired testing has been completed execution of each command has been verified At this point the size of the tested group of stations is increased and station interaction of this larger group can be monitored For this phase of testing the same checks outlined in sections titled Testing the Sending Station and Testing the Receiving Station can be made but without the need to test each individual command At this time all station processors remain in the TEST mode In this procedure gradually increase the size of the tested group until all stations are communicating Operation Once the interaction of all station interface modules has been ch
76. eceiving station as described in section titled Testing the Receiving Station Then check any other commands as necessary using the applicable procedures of sections titled Power up Testing the Sending Station and Testing the Receiving Station 9 17 Chapter 9 Start up and Troubleshooting Troubleshooting 9 18 Testing the Receiving Station The receiving station is checked with the sending station for one purpose verification of data transfer Although this procedure may be time consuming it is essential in initial start up testing and for testing whenever a command is added at a station The station communication adapter module upon receiving a command message executes the command at its station processor and formats and transmits a reply message back to the sending station START DONE and REMOTE LOCAL FAULT bits indicate proper execution of this procedure The checks performed in testing the sending station therefore can indicate and help to isolate the source of a problem that prevents the command from being executed The checks at the receiving station help to verify that program addressing and station number switch selection is correct and that data are being sent to the intended station When a command has been initiated and tested at its sending station perform the following procedures at the receiving station 1 the programming terminal at that station display the instructions for th
77. ecked the station processors can be put into operation one at a time You must determine which controller you intent to put in the RUN mode initially and in what order other stations are to be added in the RUN mode Monitoring of station interaction can continue during these procedures By adding stations one at a time you can exercise maximum control over the application and monitor controller behavior Power Up Only the 2 stations being examined in the first phase of start up should be ON Follow these steps in powering up each of these stations 1 the processor mode select switch to PROG position 2 Turn power ON at the station processor and communication adapter module Observe power supply and processor indicators for proper status 3 While observing the indicators of the communication adapter module turn the mode select switch to TEST position Within a short time the PROG indicator on the module should turn ON briefly then OFF This indicates that the module has checked the communication zone rungs of program If this indicator remains on an error may have been detected in these rungs Should this be the case check the ERROR CODE storage word as described in step 4 If this indicator does not turn on the communication zone of program may be incorrectly entered Check this zone if necessary The indicator labeled PROC should be OFF If this indicator is ON check for a processor fault indication or poor Da
78. ered as the timeout preset for the module This chapter dovetailed with chapter 6 It discussed command initiation execution and monitoring and their association with START DONE bit timing Normal operation START DONE bit status Faulty operation Control of START bit ON OFF input status Transition of an input device from ON to OFF and OFF to ON Timed start bits Diagnostic FAULT rungs Timeout preset values Programming a preset code Optional user programmed timeouts Chapter 8 discusses interfacing a KA2 with other modules on a Data Highway mastership of the highway and Data Highway computer commands 7 19 General Floating Master Chapter Station Interfacing To execute commands a 1771 K A2 communication adapter module at one station interacts with all other stations interface modules on the Data Highway This chapter describes this interaction of station interface modules Because much of this interaction is transparent to user programming the information given here is largely for background However an understanding of station interaction is useful in optimizing use of each individual communication adapter module and of the Data Highway as a whole Specifically the information aids in an understanding of the following Floating master operation and polling Message types Sequence of messages for command execution Acknowledgements Re tries of transmitted messages
79. escribes station interface module interaction along the Data Highway Chapter 9 describes start up and troubleshooting tools and procedures Chapter 10 provides aids to design and documentation of a Data Highway that uses a communication adapter module This chapter discussed Features of a 1771 KA2 Communication Adapter Module How the module fits into an A B Data Highway system What a 1771 K A2 does and the A B PLC data processor it works with Publications available for Data Highway and PLC 2 family PCs In chapter 2 you will learn about a Data Highway station and the KA2 s role in station function 1 5 General Chapter Station Hardware The following components make up a Data Highway station with a PLC 2 family PC Communication Adapter Module Processor PLC 2 I O adapter module for PLC 2 20 and PLC 2 30 processors Bulletin 1771 I O chassis Power supply Data Highway Processor cable Data Highway cable dropline Figure 2 1 shows the configuration of a typical Data Highway station for PLC 2 20 and PLC 2 30 processors Figure 2 2 shows a typical configuration for the mini processor module Figure 2 1 Typical Station Configuration PLC 2 20 and PLC 2 30 Processors Data Highway Cable Trunkline Station 1 Processor Station gt Chassis Dropline 5 100 feet maximum Communication Adapter D 0 F Mo
80. et Value 7 14 The OFF DELAY timer is useful in this application because it is continually reset when its rung conditions go TRUE This means that the timed bit 03015 remains on for as long as any FAULT bit is changing state during programmed re tries This keeps the output indicator on until after the DONE bit indicates command completion NOTE Using the rungs of Figure 7 7 the indicator goes ON automatically at power up or whenever the mode select switch on the processor is changed from the PROGRAM LOAD or PROG mode to any other mode However the indicator only remains on initially for the preset interval after this time the indicator is valid for fault conditions Rungs 1 and 2 examine all 8 FAULT bits of each type Should fewer than 8 command rungs be programmed at a station processor fewer bits need be examined Then should command rungs be added subsequently the appropriate bits could be addressed in rungs 1 and 2 Conversely if more than 8 command rungs were programmed at a station additional rungs would be needed to examine both REMOTE and LOCAL FAULT bits for the additional commands Status bits controlled by these additional rungs could then be examined in branches of rung 3 parallel to those shown Of course other methods can be used to monitor REMOTE and LOCAL FAULT bits Such factors as availability of output terminals memory space and type of application dictate the specifics of FAULT bit monitoring and program
81. evisions When you connect a 1770 T3 terminal revision G or later to a 1771 KA2 module series A revision D or later and perform program uploads with the 1770 T3 terminal in the PLC 2 mode the terminal does the following Uploads 1 Displays the prompt UPLOAD IN PROGRESS PLEASE WAIT FOR COMPLETION 2 disables the PLC 2 mode 3 displays the prompt UPLOAD COMPLETED PRESS ANY KEY TO CONTINUE 4 re enables the PLC 2 mode and forces are maintained after you press any key 8 7 Chapter 8 Station Interfacing 8 8 Downloads For program downloads with the 1770 T3 terminal in the PLC 2 mode the terminal 1 displays the prompt DOWNLOAD IN PROGRESS ALL FORCES CLEARED 2 displays a mode select menu 3 displays the prompt DOWNLOAD COMPLETED ALL FORCES CLEARED 4 displays a mode select menu When you connect a 1770 T3 terminal revision G to a 1771 KA2 module series A revision D and perform program uploads when the 1770 T3 terminal is not in PLC 2 mode the terminal displays a mode select menu and the following prompts 1 UPLOAD IN PROGRESS PLEASE WAIT FOR COMPLETION 2 UPLOAD COMPLETED If you perform program downloads when the terminal is not in PLC 2 mode the terminal displays a mode select menu and the following prompts 1 DOWNLOAD IN PROGRESS PLEASE WAIT FOR COMPLETION 2 DOWNLOAD COMPLETED Chapter Summary Chapter 8 Station Interfacing Using Two Communication Modules
82. g station is operating and has received the message and it indicates that the received command or reply message is in intelligible format Should the proper acknowledgment not be received a fault in the receiving module may be indicated In this event the master station communication adapter module re tries transmission of the message The communication adapter module attempts several re tries for a command or reply message Re tries are automatic transparent to the user program If re tries are unsuccessful a LOCAL FAULT bit may be set ON at the local sending station processor LOCAL FAULT bits are described in chapter 6 Acknowledgements are sent only by a station that is in the receive mode not the current master station Message Priority Each message transmitted over the Data Highway communication link has one of these priority levels normal and priority These priority levels determine the order in which stations obtain mastership and the order in which messages are transmitted Priority messages of a given type either command reply or polling will always be transmitted before normal messages of the same type The programmer designates a priority level for each command message The command code an element in each command rung specifies the priority level of the command message The station that receives a command message automatically establishes the same priority level for its Commands From A Computer Chapter 8
83. gs use the standard controller instruction set However the meaning of these instructions and addresses differs significantly from their meaning in standard ladder diagram programming For this reason each programmed element in a communication zone rung must be understood as it is described in this chapter not as it would normally be understood in a ladder diagram logic context In several instances the 3 or 5 digit number entered above the communication zone rung element has no relation to an actual data table address This chapter specifically identifies this type of number as either a station number or code Where one of these designations is given the actual data table bit or word at that address is not affected by KA2 module operation and may be used in the balance of the user program For the purpose of this description the reference point is termed the local station All other stations are then considered remote stations These rungs are entered at the local station so that it can send commands to or receive commands from a remote station Obviously this reference point is not fixed Each station as it is being programmed is considered the local station at that time 5 1 Chapter 5 Communication Zone Rungs Overall Format The overall format for the communication zone of program is shown in Figure 5 1 This figure shows each type of rung that can be entered in this Zone The actual communication zone rungs
84. h does not prevent unprotected read commands from being sent by a communication adapter module FIRST SECOND MODULE Use switch 6 for first second module selection Set switch ON Use this setting when connected directly to any compatible processor except PLC 2 1772 LR OFF Use this setting when the KA2 module is connected to a PLC 2 1772 LR a 1771 KG series B module or another KA2 module Station No Switch Group You must designate a unique station number for each communication adapter module on a Data Highway This designation is made by the programmer and switch selected on the station number switch group of the module Chap Module Installation ter 3 The station number switch group comprises 3 switch assemblies SW2 SW3 SW4 on the module circuit board as Figure 3 3 indicates These switches determine the station number of each communication adapter module The station number is a 3 digit octal number from 0108 077g or 110g 376g Each of the 3 switch assemblies in this group is set to represent an individual digit of this station number Figure 3 3 shows the combination of switch settings for each digit Figure 3 3 Station Number Switch Settings OFF 2 N ON ON Il E OFF OFF F Ld SW SW3 SWA SWITCH SETTING DIGIT SWITCH SETTING DIGIT No
85. h priority messages slow all traffic on the network In general you should limit the number of high priority messages to less than 146 of the total traffic on the Data Highway A communication adapter module can execute commands from a computer connected through a communication controller module cat no 1771 KE or KF The command set of the computer includes the command set of the 1771 K A2 module a Protected write a Protected bit write Unprotected read Unprotected write 8 5 Chapter 8 Station Interfacing 8 6 Unprotected bit write These commands have the same execution sequence and memory access as the same commands from a communication adapter module In addition to these commands the command set from the computer includes the following which can be executed by a PLC 2 family processor Privileged read Privileged write Diagnostic loop Enter download mode Enter upload mode New for 1771 KA2 Exit upload download mode Diagnostic read Diagnostic counters reset Set data table size New for 1771 K A2 Diagnostic Status Privileged commands give the computer the capability to read from or write into the entire processor memory This includes both data commands and user program areas Privileged commands are used chiefly to load programs from a computer to a station processor on the Data Highway During program downloading outputs are held in their last state by the processor
86. he communication adapter module The command rung lists the type of command and the memory areas affected and allows command execution to be initiated in the user program There are 2 basic command rung formats that differ only in terms of the unit of memory which they control The basic command rung formats are Word command format Bit command format Use the word command format for commands that transfer one or more data table words between stations These are unprotected write read and protected write commands Use the bit command format for commands that control from one station one or more data table bits at another station processor These are unprotected bit write and protected bit write commands In both formats the command rung begins in a similar manner Refer to Figure 5 5 The first rung element is an EXAMINE ON instruction addressing the START bit The second rung element termed the command code tells the remote station number type and priority of the command Section titled Message Priority chapter 8 describes command priority For most commands normal priority is preferred 5 7 Chapter 5 Communication Zone Rungs Start Command Bit Code AAAPX Figure 5 5 Command Rung Format 02707 5 8 E REFERTOFIGURES b 5 6 AND 5 7 AAA REMOTE STATION NO P PRIORITY INDICATOR 1 PRIORITY MESSAGE 0 NORMAL MESSAGE X COMMAND TYPE 0 PROTECTED
87. he START bit as the input condition to a counter as shown in Figure 9 6 Using this optional counter you can verify that the command is being executed continuously To use this optional counter insert this additional rung within the ZCL area between rungs 3 and 4 Figure 9 6 Optional Test Counter Increments to show continuous sending of tested command message Start Bit 03210 057 lE CTU Insert between optional test rungs 3 and 4 if needed Note that the counter value shown on the programming terminal may not display the actual number of times a command has been sent due to CRT delay time However the purpose of the counter is to provide an indication to the troubleshooter that the command is being continuously executed rather than to give an actual count of the number of times it is executed Again the use of these test rungs is optional subject to the discretion of the programmer An advantage of these rungs is that they may be kept at the end of the user program after start up is completed This enables use of these rungs in subsequent troubleshooting or later testing as when a command rung is subsequently added to the communication zone of program Of course these rungs can be removed after start up is completed at the programmer s option Recommended Documentation For testing and troubleshooting command execution the following documentation should be available at each station processor Copy
88. he ZCL area Figure 9 5 Optional Test Rungs Input address for Force On manipulation Input address which is always turned OFF by 1 0 scan 111 00 f zcl Start Bit 03210 Rungs may L 7 be left in program for subsequent Done Bit Start Bit EE 032 00 03210 shooting E U ZCL The input image table bit examined in rung 1 must always be turned OFF by the processor I O scan This bit can be any unused input image table bit For this purpose choose a bit that is not usable because its corresponding I O chassis slot contains an output module Because the processor turns this bit OFF on each I O scan the ZCL area is disabled unless both of these conditions are met The programming terminal is connected to the processor that is to the communication adapter module PROGRAM INTERFACE socket The addressed input image table bit is FORCED ON When both of these conditions are met the commands programmed at a station processor can be initiated and monitored To test individual commands the addresses of the corresponding START and DONE bit are entered into rungs 2 and 3 In this manner each command can be tested individually Chapter 9 Start up and Troubleshooting These rungs send the command continuously as long as the ZCL area is enabled As a quick check of this continuous command execution and completion another rung can be added to the test rungs within the ZCL area This rung examines t
89. hese functions 3 10 Chapter 3 Module Installation Figure 3 7 Industrial Terminal Connection Kos E Q i gms ig key US q f TI Channel A Program Panel Interconnect Cable cat no 1772 TC 10219a I Data Highway Processor Cable Connector The bottom connector of a 1771 K A2 module is labeled PROCESSOR The communication module communicates with the station processor through this connector The Data Highway Processor cable cat no 1771 CN CO CR connects from this socket to a socket on the fact of the station processor On a PLC 2 20 or PLC 2 30 this is the connector labeled PROGRAM PANEL on a Mini PLC 2 or Mini PLC 2 15 the connector is labeled INTERFACE Refer to Figure 3 8 and on a Mini PLC 2 05 the socket is labeled INTFC 3 11 Chapter 3 Module Installation Figure 3 8 Data Highway Processor Cable Connection PLC 2 20 Communication Adapter Processor Module cat no 1771 KA2 Bi A e e d D Fonnector
90. hown in Figure 5 3 A In this format a BRANCH START precedes a group of 3 GET instructions The first GET instruction address is the station number of a remote station The next 2 GET addresses define the word boundaries of the accessible data table area in the local station processor The specified remote station may control any bit or word within three boundaries through protected commands Figure 5 3 B illustrates the memory area that is now accessible to protected commands from remote station 010 due to the memory access branch of Figure 5 3 A Multiple memory access branches can be listed in a single memory access rung Each group of 3 GET instructions must be preceded by a BRANCH START instruction This is true in all cases even when only one memory access branch is defined BRANCH END instructions can be used to fit the memory access rung into the ladder diagram display format Use output instruction OUTPUT ENERGIZE 02707 to fit the memory access rung into the proper display format This output instruction has no significance in memory access rung logic 5 5 Chapter 5 Communication Zone Rungs 5 6 Figure 5 3 Memory Access Example Memory Access Boundaries in Local Station Data Table a WM Protected Commands From Remote Station No 010 7 2 Words Branch Start Instruction Branch End Instruction Remote Startin i Station No Addis Adress B a 020 me 023
91. in Appendix A Chapter 7 continues discussion about command initiation control bits fault words and monitoring 6 7 General START DONE Bit Timing Chapter Command Initiation Execution and Monitoring This chapter describes the support programming for commands at each station processor This programming uses the START DONE and REMOTE LOCAL FAULT bits described in chapter 6 to initiate and monitor command execution Using these recommended techniques the programmer coordinates communication zone programming with his application program The START bit that initiates a command is program controlled the DONE bit which indicates command completion is communication adapter module controlled The timing relationship of START and DONE bits is used by the programmer to initiate and terminate commands The following sections describe this relationship in normal operation and describe the automatic responses that result from faulted operation Normal Operation Command execution begins when the user program turns a START bit ON normally with a LATCH instruction The 1771 KA2 communication adapter module detects the ON state of this bit and then begins the operations necessary to format and transmit a command message When the remote station communication adapter module receives the command message it acknowledges it Then while normal Data Highway operation continues the remote station communication adapter module executes
92. ion adapter module monitors the status of START bits and executes the corresponding command when its START bit is set ON The DONE bit as its name implies indicates command completion This bit controlled by the KA2 is set ON when a command is executed Each command rung examines a unique START bit Thus one pair of START DONE and REMOTE LOCAL FAULT words has enough bits for up to 8 command rungs Should more command rungs be programmed select additional word pairs as necessary To optimize memory use and minimize the time required by the communication adapter module to scan START bits use all 8 START bits in one word pair before using another START DONE word For the same reason when programming communication zone rungs group in sequential fashion command rungs that use the same START DONE word REMOTE LOCAL FAULT Word Chapter 6 Status Words As Figure 6 1 shows the selection of a START bit in the program not only causes a corresponding DONE bit to be controlled in the same word but also causes REMOTE and LOCAL FAULT bits to be controlled in the next data table word A REMOTE FAULT and LOCAL FAULT bit are controlled for each command For a command the position of each of these FAULT bits within their respective bytes corresponds directly to the position of START and DONE bits for that command The KA2 controls REMOTE and LOCAL FAULT bits The module sets a FAULT bit ON when a command cannot be executed due to a hardware
93. ion processor Disconnected data highway processor cable Error detected in communication zone of program at remote station proccessor Receiving Remote Station 9 8 10866 1 ERROR CODE Storage Word The ERROR CODE storage word is especially useful for station start up The codes displayed in the lower 2 digits of the ERROR CODE word may indicate an error in programming switch setting or certain other conditions that prevent normal communication adapter module operation The ERROR CODE storage word is addressed by the second GET instruction in the header rung Refer to Figure 9 4 This is the first rung of the communication zone of program Local Station No N 011 Chapter 9 Start up and Troubleshooting Appendix A lists each ERROR CODE and its meaning Figure 9 4 Header Rung Error Code Storage Word Location Timeout oa Code 077 015 02707 6 16 Test Rungs Optional For start up and troubleshooting testing you must have some means for control of each START bit To execute a command during testing you can energize the START bit for each command Here s the way it happens The START bit is controlled by a rung of the user application program The most direct way to control this bit in troubleshooting therefore is to manipulate the conditions of the rung to energize the START bit If this c
94. ior and in troubleshooting Subsequent sections describe each of these parts of the module and other aspects of module hardware that are significant in its set up and installation Each communication adapter module in a Data Highway installation must have a unique station number This station number is used to address commands to the module from other stations Figure 2 3 Communication Adapter Module cat no 1771 KA2 Side view Indicator Connectors A 10862 1 Switch Cover Connectors The front of a 1772 KA2 module has 3 cable connectors labeled DATA HIGHWAY PROGRAM INTERFACE PROCESSOR See Figure 2 4 2 3 Chapter 2 Station Hardware Figure 2 4 Module Connection Summary Data Highway Cable User Assembled Program Panel Interconnect Cable Cat no 1772 TC OOCO m Program Panel or Interface Socket on Processor E Y E d mEE EET Q 3 Data Highway m Processor Cable UL ES AT cat no 1771 CN CO CR Industrial Terminal System cat no 1770 T1 and T2 10863 1 Data Highway Connector The upper connector of the module accepts the 15 pin Data Highway dropline cable Through this connection a singl
95. is bit is then examined by the program to control the status of bit 01001 The output bit 01001 cannot be directly addressed by the bit write command However by controlling the storage bit and examining it in the program the same effect is achieved Figure 4 3 Bit Control Use example Control of this output desired However bit already addressed by Input output intructions E Output 11113 d Fa a Original Rung Input Output 11113 4 IF Storage Bit 12104 Nee Control bit through bit write command to I control output 01001 b Recommended Technique 4 6 Read Command Accessible Data Table Locations PLC 2 Processors Chapter 4 Commands The second restriction listed above applies when the destination station is a PLC 2 family PC For these processors when the station communication adapter module receives a bit write command it manipulates the 8 bit byte of the 16 bit memory word in which the addressed bit is located This may be the low byte containing bits 00 07 or the high byte containing bits 10 17 Should program instructions control other bits within the same byte there is a slight possibility that the communication adapter module may write over programmed status for these program controlled bits This would occur only if the program caused a bit to be altered during the time the communication adapter module was executing a received bit write command Therefore when using the
96. is is an octal number from 010g to 077g or from 110g to 376g The ERROR CODE storage word is a status word in the data table of the local station processor controlled by the communication adapter Section titled Error Code Storage Word chapter 6 describes the significance of the ERROR CODE storage word The timeout preset code gives a programmed timeout interval for command completion Based on the 3 digit value entered in the address field of this GET instruction the communication adapter module monitors command execution for all commands sent from a station In the examples in this publication the number 015 is entered as the timeout preset code This value which designates a 5 second timeout preset is suitable for most applications The significance of this preset code its computation and timeout considerations are described in section titled Timeout Preset Value chapter7 Memory Access Rungs The memory access rung defines data table words that you can access with the following commands a Protect write a Protect bit write Protected commands received from a remote station may control only those local station processor memory areas listed in memory access rungs 5 4 Chapter 5 Communication Zone Rungs Note that memory access rungs are not needed to allow unprotected commands only protected commands require a memory access rung A memory access rung is composed of one or more memory access branches as s
97. its to UNLATCH the START bit An important assumption underlies the examples outlined in sections titled ON OFF Input Status Transition and Timed and shown in Figures 7 3 through 7 5 Here the program automatically re tries transmission of a command in the event of a fault Only the DONE bit terminates attempts at command execution a LOCAL or REMOTE FAULT bit response causes the program to re initiate command execution This type of programmed re try is not to be confused with the re try procedure of the 1771 KA2 module itself transparent to user programming the module automatically attempts several re tries of a message before it sets a FAULT bit Section titled Floating Master in chapter 8 describes these automatic re tries of the module Programmed re try has distinct advantages As the communication adapter module continuously tries to send the command message any data content of the message for a write command is continuously updated As soon as the fault condition is corrected the message is sent with the latest data In addition once the command is completed the program automatically UNLATCHES the START bit This eliminates the need for a manual reset of the START bit when a fault condition is corrected ON OFF Input Status The ON or OFF status of an input device can be used to LATCH the START bit Figure 7 3 shows rungs for this type of command initiation 7 5 Chapter 7 Command Initiation
98. ly Note that ERROR CODES 01 29 are intended as aids in start up debugging of the communication zone of program Thus the reference number stored in this word can be a valuable tool for debugging purposes For ERROR CODES 30 99 the upper byte stores a 2 digit counter This counter shows the number of ERROR CODES 30 99 written into the storage word by the communication adapter module The counter increments each time a different ERROR CODE storage word These codes are generally to be displayed on a programming terminal rather than used in application programming They have special value in station start up when programming errors are detected in the communication zone of program By viewing the header rung of the communication zone the programmer can examine a displayed ERROR CODE and the least significant digit of the counter in this word Section titled Header Rung chapter 5 describes a header rung In some instances however it may be preferable to display the 2 digit error code using a 7 segment BCD numerical display controlled from output modules of the controller This 7 segment display mounted at an operator s station can provide a useful troubleshooting aid for quickly locating fault conditions Chapter Summary Chapter 6 Status Words This was the WORD and CODE chapter and it discussed START DONE REMOTE LOCAL FAULT bit storage REMOTE LOCAL fault word Error code storage word Error code list is
99. mand Initiation Execution and Monitoring 7 16 Timeout preset monitoring is intended as a backup for the other communication monitoring functions of the module It is designed to signal any condition where the module has not completed its communication with another station or detected some fault condition within a short time Because this timer is primarily intended as a backup for some LOCAL FAULT type of situation its preset value is not critical In the examples in this manual a nominal value of 5 seconds coded 015 is programmed as the timeout preset value This value is appropriate for most applications Programming the Preset Code The timeout preset code for Data Highway communication is entered in the header rung of the communication zone of program The address field of the third GET instructions in this rung is used for the timeout preset code Figure 7 8 shows the position of this rung element The 3 digit address of a GET instruction is an octal base 8 number Because only octal values can be entered in this address field the timeout preset value is a code computed as outlined in this section As section titled Timeout Preset Value points out the timeout preset is not a critical value For most applications a 5 second present is acceptable The code for this timeout preset is 015 However there may be instance where another timeout preset interval is desired Table 7 B lists the 3 digit codes for intervals from
100. mmand code identifies the following Remote station number Priority status of the command priority or normal Type of command NOTE The command code uses the address of an EXAMINE ON instruction but does not examine or control any bit in the data table of the local station processor Figure 5 5 shows the coding for this rung element Word Command Format When the command code specifies a protected write read or unprotected write command use the format shown in Figure 5 6 Figure 5 6 Word Command Format Local Station Processor Start Command Data Table Boundaries Bit Code 2 03210 02000 BBB 02707 ke 6 6 Remote Station Processor Data Table Address Legend AAA Beginning word address of remote station processor for write read operation BBB Beginning Word Address of local station processor for write read operation CCC Ending Word Address at local station processor for write read operation 5 9 Chapter 5 Communication Zone Rungs 5 10 This format uses 3 GET statements The address position of the first GET statement lists a remote station data table word The specified command operation begins at this memory location The second and third GET statements define the starting and ending boundaries of the data table words in the local station processor These words are the beginning and ending data table locations for the words to be transferred in the write or read operation
101. n Stations A A 1 Send Command Reply Messages ee Acknowledgment 2 Send Polling Message Sequence Signal if Ready Ion 12360 As master a communication adapter module can send the following types of messages Command Reply Polling Chapter 8 Station Interfacing The function of both command and reply messages is the transfer of data between stations As soon as the communication module attains mastership it sends its command and reply messages up to a maximum number 16 for the 1771 KA2 After the module sends its command and reply messages it transmits a sequence of polling messages By this sequence it selects the next station to be master of the Data Highway communication link Command Messages A command message from the master communication adapter module instructs another station interface module to execute a command In general a command from a communication adapter module can do one of the following Write data table data to another station Write bit status to another station Request data table data from another station through a read command The command rung entered in the communication zone of user program instructs the communication adapter module to format a command message Once this message is sent execution of the command begins Command
102. nication Zone 5 1 CP 5 1 Header Rings sua xn 5 3 Memory Access RUNGS 5 4 Command RUNES 5 7 DelimiterRUng t on a d On don dota brated E 5 11 Chapter SUMMAN siciusaaeeiasximecevadee canes water 5 12 Table of Contents Status WOrdS 2 25b aaci ads dew Vndc des Seed 6 1 General Sosa am UA v Vet TUTUP E MEE Eds E 6 1 STARTIDONE WO en ch tn bbb wed der oo e cb we 6 2 REMOTE LOGAL FAULT 6 3 Error Code Storage Word sus axe sat d REOR GRAUE OE RH Hur 6 5 aj Wer MEC 6 7 Command Initiation Execution and Monitoring 7 1 sip ana VEL 7 1 STARTDONE BIETMING 24424054 rata OD ho or ac c ur 7 1 Controlling The 7 4 REMOTE LOCAL FAULT 7 10 Timeout Preset 7 14 Chapter SUMMAT deese us cane lm eoa cp OH a CON weaned bas 1 19 Station 8 1 Soc eisernen nee 8 1 Floating Master ies Rica tee Rr cen pu a wae Re ace eee 8 1 Commands From Computer
103. of restarting the 1771 KA2 or shutting it down ON Shuts down the module OFF Automatically restarts itself When a hard error occurs it normally indicates fairly severe communication problems that should be corrected before starting Such errors usually involve bad cabling or noise REVISION D The third switch in the Write Option Switch assembly on the 1771 KA2 module formerly the Shutdown Automatic Restart Switch will change function for revision D and become the Execute Download in Run Program switch 3 3 Chapter 3 Module Installation 3 4 RECEIVE PRIVILEGED WRITE SWITCH Switch 4 determines whether the module can execute received privileged write commands These commands can be issued only from a computer connected through a communication controller module cat no 1771 KE KF These commands give the computer the capability to alter the user program memory of the station processor Set this switch as follows ON Enables a 1771 KA2 to execute received privileged write commands OFF Disables the 1771 K A2 from executing received privileged write commands SEND UNPROTECTED COMMANDS SWITCH Switch 5 determines whether the module can send unprotected write or bit write commands to another station Set this switch as follows ON Enables the module to send unprotected write and bit write commands OFF Disables the module from sending unprotected write and bit write commands This switc
104. om the input module each I O scan Note that this restriction does not prevent any word of the input image table from being written to another station This control restriction applies only when attempting to write data into input image table locations Word 377 Word 377 has special status functions within the PLC processor For this reason the communication adapter module must not execute write or bit write commands into this word A read command from a local station can address word 377 at a remote station PLC processor 4 9 Chapter 4 Commands Accessible Data Table Locations PLC 3 Processors 4 10 Word 000 Reserve word 000 of the PLC processor output image table when using a KA2 This means that commands from another station must not be programmed to control word 000 or any of its bits Each PLC PLC 2 station on a Data Highway can read from or write to only one specific buffer file at a PLC 3 station That is the PLC 3 input file with a number that corresponds to the station number of the PLC PLC 2 station For example the read write files assigned to PLC PLC 2 stations 1 to 100 octal would be as follows PLC PLC 2 Station Assigned PLC 3 Input File Number octal for Read Write Access 001 1001 002 1002 003 1003 004 1004 005 1005 006 1006 007 1007 1008 1009 Not assigned 010 1010 011 1011 012 1012 0770 1077 100 1100 PLC PLC 2 station numbers are octal while PLC 3 input files have decimal
105. onitoring user commands as described in chapters 5 and 7 That your application program is fully tested The last point is very important Testing your application program at each station is essential for proper operation This means that the application program must be tested before the Data Highway is tested You must test the program that controls output devices including those parts of the program that use data transferred from other stations In a new installation you must complete all start up procedures of the controller before attempting to test Data Highway operation This includes complete testing of I O devices I O wiring and program sequencing Procedures for start up of a new controller are covered in other publications A lists of these publications appears in chapter 1 In many cases Data Highway capability is added to an existing controller installation Here the application program may be only slightly modified to use data from other stations However any editing or change of the program must be tested at the controller so that errors can be corrected before the program is put into full operation Chapter 9 Start up and Troubleshooting Overall Approach In start up testing it is best to limit the number of things happening at one time By carefully limiting the scope of start up testing to a small number of variables the source of a problem is more readily detected Paired Testing In the early stages of
106. ould the 1771 KA2 module detect an error in data transmission with the processor it turns the PROC indicator on This may mean one of the following Disconnection of the Data Highway Processor cable between the communication adapter and the processor Fault in processor operation ncorrect selection of processor link communication rate on the module Refer to section titled Write Option Switch Assembly chapter 3 The section titled Module Indicators in chapter 9 describes the use of indicators in troubleshooting Switches There are 3 sets of switches on the 1771 K A2 module circuit board These switches are beneath the small switch cover plate on the component side cover of the module Refer to Figure 2 3 The programmer selects the settings of these switches for each communication adapter module based upon such variables as station number command capabilities and type of station processor Switch settings are a part of module installation described in chapter 3 2 7 Chapter 2 Station Hardware Processor 2 8 Module Specification Summary Table 2 A lists operating specifications for a 1771 K A2 module Table 2 A Operating Specifications Function e Interface entire PLC 2 family programmable controller to the Data Highway Location e Bulletin 1771 1 0 Chassis any slot except furthest left Communication Channels e To Data Highway e programming terminal or second module in dai
107. ply includes station information in module s data field Enter download mode puts PLC 2 family processor into download mode Use before sending physical write commands to station Enter upload mode new on KA2 module puts PLC 2 family processor into upload mode Use before sending physical reads to station Exit download upload mode takes PLC 2 family processor out of upload download mode Use to restart processor after uploading or downloading Physical read reads bytes of data from PC data table or program memory Use the upload contents of PLC 2 family processor memory to computer Physical write writes bytes of data into PC data table or program memory Use to download computer contents to PLC 2 family processor memory Set data table size sets data table size for PLC 2 family processor Use before physical writes on PLC 2 family processor All PLC 2 family data tables are configurable but some have wider ranges than others Check the appropriate manual for the processor in your application Later chapters cover the following Command programming chapter 5 Command status bits chapter 6 Command initiation and execution monitoring chapter 7 4 2 Protected Unprotected Chapter 4 Commands Terminology Remote Local Station In this and later chapters we use the terms remote station or local station The local station is the point of reference When describing the commands
108. program panel CRT this status indication is similar With these terminals an instruction symbol is intensified when the instruction is logically TRUE For an input instruction this means that the condition specified by the instruction has been met For an output instruction this means that the instruction is being carried out An EXAMINE ON instruction for example is intensified when the corresponding input device is ON This means that the memory bit addressed by the instruction is ON Conversely an EXAMINE OFF instruction is intensified when the memory bit it addresses is OFF 9 5 Chapter 9 Start up and Troubleshooting For A RUN For B 9 6 Note that this status indication is provided in both RUN and TEST modes In the PROGRAM LOAD or PROG mode however intensity of a displayed instruction indicates cursor position Figure 9 2 illustrates the significance of an intensified instruction for both the industrial terminal and the PLC program panel Figure 9 2 Meaning of Intensified CRT Display Intensified insturction indicates cursor Editing changes to be made at this point in the rung H JE A Cursor Note In run or test modes blinking indicates cursor position PROG Intensified instruction indicates specified condition true H an B Normal Normal intensity indicates specified condition false The PLC 2 program panel meanwhile has a different type
109. r 9 Start up and Troubleshooting 4 Liftthe plastic lever on the module to break its backplane connection 5 Firmly grasp the sides of the module and pull it gently from the I O chassis slot Installing the Replacement Module 1 Setmodule switches to proper positions then replace the switch cover 2 Insert the replacement module in the I O chassis Snap down the latch on the top of the chassis and re connect the cables to module sockets Module power up is described in section titled Power up Station Disconnection For most troubleshooting and startup purposes a station can be disconnected from the Data Highway communication link simply by disconnecting the station dropline from the DATA HIGHWAY socket of the module However should a station be disconnected for an extended period or should a dropline no longer be needed at any point along the Data Highway cable the station should be disconnected at the 1770 XG tee connector or the 1770 SC station connector whichever one was used To disconnect a station joined by a tee connector remove the station dropline from the connector Then remove the male and female truckline cables from the tee and connect them to each other To disconnect a station joined by a 1770 SC connector remove the SC s cover then disconnect the wires from terminals 6 and 8 If the dropline cable was longer than 10 ft and the drain wire was connected to terminal 7 disconnect that one
110. r it is polling RCVG The receiving indicator turns on when the module is receiving a message addressed to it Otherwise RCVG is off When both the RCVG and XMTG indicators are on the module is current master of the Data Highway and is polling The section titled Polling in chapter 8 describes polling procedure RDY The green message ready indicator turns on when the module has messages ready to transmit With this indicator on the module is ready to assume mastership when it is polled Chapter 2 Station Hardware PROG The red program status indicator tells you the status of module checks on the communication zone rungs of the user program The section titled Overall Format chapter 5 describes these rungs The module first checks these rungs at power up When it locates the header rung of this zone the module turns the PROG indicator on After it checks the rungs provided no errors are found the module turns the PROG indicator OFF However if the module detects any programming error in the communication zone of the program this indicator remains ON In this event the module cannot function You must check the communication zone of the program and correct any errors Start up procedures are described in chapter 9 PROC The red processor link status indicator gives the status of error checking diagnostics for communication adapter processor communication The PROC indicator is normally off Sh
111. ramming terminal On the industrial terminal position the cursor on the FORCED instruction and press the following keys FORCE ON REMOVE On the program panels press the following keys to remove a FORCE ON function SELECT FORCE ON REMOVE The FORCE ON function is also removed when the programming terminal is disconnected from the station Monitoring REMOTE LOCAL FAULT Bits This second step in command checking requires that the status indicator of the programming terminals be monitored for FAULT bits Use the following steps to observe the instructions that examine the FAULT bits 1 Tum the processor mode select switch to TEST position 2 Use the SEARCH functions of the programming terminal to locate instructions that examine FAULT bits SEARCH functions are described in section titled Programming Terminals 3 Observe the ON OFF status indicator of the programming terminal for each DONE and FAULT bit corresponding to the command These ON OFF status indicators are described in section titled Programming Terminals Either a DONE bit FAULT bit will turn on for each command If the REMOTE or LOCAL FAULT bit turns ON for the command sent some hardware related fault or programming error can be suspected Check the connections and equipment indicated in Figure 9 3 If the DONE bit turns on the command has been executed properly by the sending station After checking a command in this manner check the r
112. re 2 1 and Figure 2 2 show the connections made with these cables You can order Data Highway Processor cables in 3 lengths 1 5 ft cat no 1771 CN 3 5 ft cat no 1771 CO 10 5 ft cat no 1771 CR The 2 shorter cables are intended for connection to a Mini PLC 2 Mini PLC 2 05 or Mini PLC 2 15 module A 10 5 ft cable is used with PLC 2 PLC 2 20 or PLC 2 30 processors You must assemble and install your own Data Highway cable dropline and trunkline segments A separate publication Data Highway Cable Assembly and Installation Manual publication 1770 6 2 1 gives information on layout make up and installation of the cable In addition to the components shown in Figure 2 1 and Figure 2 2 you can install your own equipment at or near the Data Highway station The chief purpose of additional components is to provide diagnostic or monitoring information Such devices as alarms displays and indicators can be controlled from output modules of the programmable controller to provide operating or fault information to plant personnel Minimally a single indicator should be installed to alert your personnel to a REMOTE or LOCAL FAULT condition that prevents normal message transfer The significance of REMOTE LOCAL FAULT bits and the recommended programming to monitor these bits is described in chapter 7 This chapter told you the Components of an A B Data Highway system Role of a 1771 KA2 its connectors switches
113. re 7 3 Timed The START bit may be LATCHED periodically to send a command at a user determined time interval Figure 7 5 shows example rungs for this type of command initiation 7 9 Chapter 7 Command Initiation Execution and Monitoring Figure 7 5 Timer Initiated Command REMOTE LOCAL FAULT Bit Monitoring 7 10 Done 032 02 046 1 TON 10 PR 010 AC 000 Timed Bit Start 046 15 032 12 f L Done Start 032 02 032 12 F U Local Fault 033 02 F Remote Fault 033 12 In this example timed bit 04615 is used to initiate the command at every preset interval 10 seconds This bit is examined to LATCH the START bit The DONE LOCAL FAULT and REMOTE FAULT bit are examined in parallel branches to UNLATCH the START bit In normal operation after the command is executed the DONE bit is set ON by the communication adapter module This causes the program to UNLATCH the START bit The timer then begins timing again once the DONE bit is set OFF As Figure 7 1 shows the DONE bit is reset only after the START bit is reset Note that this programming causes continuous re try of a command in the event of faulted operation When it cannot execute a command the Communication adapter module sets a REMOTE or LOCAL FAULT bit ON These bits in the data table of the station processor are located in the word immediately following the START DONE bit word They indicate not only that a command was
114. response Use of FAULT bits in start up and troubleshooting procedures is described in chapter 9 In addition to its REMOTE LOCAL FAULT bit control a 1771 KA2 module also provides an automatic timer for monitoring command completion While it functions automatically during module operation the timer uses a preset value entered in the user program This feature enables the module to monitor command execution time without using timer TON instructions in the user program Figure 7 8 shows the significance of the timeout preset interval From the time the START bit is set ON the module must set either a DONE bit or a REMOTE or LOCAL FAULT bit within the timeout preset interval Should the module detect no DONE or FAULT bit response within the preset interval some type of fault is assumed As a response to this type of timeout situation the module sets the LOCAL FAULT bit ON and Chapter 7 Command Initiation Execution and Monitoring enters the value 37 in the lower byte of the ERROR CODE storage word of the header rung Figure 7 8 Timeout Preset Significance Header Rung Code Representation ei ION In ns 6 6 6 uy X37 Code 37 Entered Timeout Preset Interval if Timeout Occurs Within this Period Done or Fault Bit Expected NN DD i Off Done Bit Of On Penge au Bit Off Local Fault re On et an a imeout Occurs UYU Bit Off Time 7 15 Chapter 7 Com
115. rocedures A 2 lets you to change remotely the size of the PC data table New with 1772 KA2 module thas second module or daisy chain capability New with 1772 KA 2 module Uses ladder diagram instructions for ease of programming Offers memory write protection through programming and switch selection 1 4 Organization Chapter Summary Chapter 1 Introduction Controls communication without need for a host computer Has automatic error checking of data it receives Has self checking diagnostics Shows status and diagnostics with LED indicators and error codes Controls DONE and REMOTE LOCAL FAULT memory bits as status and diagnostic indicators Automatically re tries messages Automatically recovers from master station fault condition Has selectable priority levels for commands Is compatible with industrial terminal system Installs easily The chapters in this manual are organized as follows and each chapter closes with a summary Chapter 2 describes the hardware components that make up a Data Highway station Chapter 3 outlines procedures for module installation Chapter 4 describes programmed commands and memory access Chapter 5 describes programming of the communication zone of program Chapter 6 describes status words that are controlled by the module at its station processor Chapter 7 outlines programming that is necessary to initiate and monitor command execution Chapter 8 d
116. rogram F 2 AC FUSE N 34 Processor J E Connector pio e G 5 LT Data Highway Processor cafe 1771 CR a Connection to PLC 2 20 or PLC 2 30 Processor T unication Adapter Mini PLC 275 2 1 f e e Connector u hway Proce Wc Labeled Cae Interface 2 i A Processor E 5 Connector LT b Connection to Mini PLC 2 Mini PLC 2 05 and Mini PLC 2 15 10865 A Second Link To provide a second communication link at a data highway station you can connect a KA2 module to another KA2 or to an A B 1771 KG series B interface module to provide an RS 232 C link and a Data Highway link These links enable communication with say a PLC 2 family processor on the highway and a stand alone computer In such a scheme the 1771 KG module can be connected directly to the PLC 2 family processor and the KA2 connected to the PROGRAM INTERFACE connector of the 1771 KG or vice versa 3 12 General Commands The primary function of a KA2 module is to transfer data to and from its station processor The module is instructed to transfer specific units of data by user programmed commands The communication adapter module transmits and receives the following set of non privileged commands Protected write Protected bit write Unprotected write Unprotected bit write Read These commands are of three general types write bit write and read
117. roller processors These processors are a PLC 2 Processor cat 1772 LR a PLC 2 20 Processor cat no 1772 LP1 LP2 a PLC 2 30 Processor cat no 1772 LP3 Figure 1 1 Communication Adapter Module cat no 1771 KA2 10862 1 a Mini PLC 2 Processor cat 1772 LN1 LN2 LN3 a Mini PLC 2 05 cat no 1772 LS LSP 1 1 Chapter 1 Introduction Mini PLC 2 Mini P LC 2 05 or Mini P LC 2 15 Programmable Con troller m About This Manual 1 2 a Mini PLC 2 15 cat no 1772 LV This module enables communication of memory data between these processors and from any of these processors to other processors on the Data Highway via communication adapter modules A typical Data Highway configuration is shown in Figure 1 2 Figure 1 2 Representative Data Highway Configuration 10 000 feet 3 048 meters maximum IL Cable Droplines 30 5 meters Data Highway Cable Trunkline ap 17 apse Station Connector 100 feet maximum 1 0 Rack Communication Controller Module cat no 1771 KE KF 0 Communication Adapter Module cat no 1771 2 Communication Adapter Module f cat no 1775 H e S H PLC 2 Family PLC 3 Progr
118. s 16 Required Required a Memory Access Branch b Local Station Processor 020 Branch 070 Data Table Figure 5 4 shows a memory access rung with multiple branches This rung lists the remote station that may control specific data table words with protected commands as follows Station no 020 can control words 070 076 Station no 017 can control words 063 065 and word 022 Station no 010 can control words 060 062 As shown in Figure 5 4 a single remote station processor may be identified in more than one memory access rung branch Figure 5 4 Memory Access Rung typical Use Branch End Instructions 076 017 02 02 d as Needed 02707 G 000 NO Start Instructions Begin Each 017 G 000 063 Le HiG 16 16 1 2 000 000 000 000 Instruction Must 065 010 060 062 Precede Output Branch G 000 G 000 6 WIG 1 16 1 16 1 Instruction 000 000 000 000 Command Rungs Chapter 5 Communication Zone Rungs For practical reasons do not exceed the display area of the programming terminal when entering these rungs You can program more than one memory access rung if needed Note however that should multiple memory access rungs be required you must enter them in succession in the communication zone immediately following the header rung and before any command rung The command rungs direct the data transfer operations of t
119. s may have power on for these procedures There are 2 steps for testing of each command from a sending station 1 Setthe START bit 2 Monitor the DONE and REMOTE LOCAL FAULT bits Each of these steps is described later Setting the START Bit The most direct way to control the START bit for test purposes is to duplicate the input conditions of the user program rung that latches this bit on If it is possible to do this easily during testing duplicate these conditions and proceed to step 2 However because this may not always be practical the set of optional test rungs as described in section titled Test Rungs Optional can be used These rungs entered at the end of the application program can be controlled to test each command individually 9 15 Chapter 9 Start up and Troubleshooting 9 16 Sample test rungs are shown in Figure 9 5 The following steps outline the procedures for programming these rungs for testing With the programming terminal connected follow these procedures 1 Display the END of program statement The key sequence that displays this part of the program is as follows SEARCH V 2 Turn the processor mode select switch to the PROGRAM or PROG position 3 Enter the test rungs in the format of Figure 9 5 with the following addresses Rung Enter the address of an unused input image table bit for the EXAMINE ON instruction Section titled Test Rungs Optional describes th
120. s so long as core memory is not being used Refer to processor manuals An auxiliary power supply cat no 1771 P2 closely resembles the system power supply shown in Figure 2 7 PLC 2 power supply module cat no 1772 P1 is not a separate unit but is enclosed within the metal chassis of the PLC 2 20 or PLC 2 30 processor PLC 2 power supplies must be series B or later for communication adapter module compatibility On both of these supplies a label on the front edge of the circuit board identifies the series level To locate this label remove AC power from the supply and remove the metal front plate that covers the module If the label shows the catalog number but not the series level the module is series A Otherwise series B or later is indicated 2 11 Chapter 2 Station Hardware Figure 2 8 PLC 2 Power Supplies E 5 Et C d D d D AC FUSE id Mo o oH d D 17 Cle e EC j e d d D AC FUSE 359 R d D L4 0 b PLC 2 Auxiliary Power Supply 2 12 10236 1 10236a Cables Other Optional Equipment Chapter Summary Chapter 2 Station Hardware A 1771 KA2 module requires the following cables for installation Data Highway Processor cable cat no 1771 CN CO CR User assembled Data Highway cable Figu
121. seful starting point when initiating a Data Highway installation or when trying to locate a fault condition The methods described in this chapter can be used to test any station that contains a Bulletin 1772 programmable controller and a 1771 KA2 communication adapter module Methods for start up and troubleshooting of other processors are described in other manuals When using a computer connected through a 1771 KE KF communication controller module additional procedures are available for start up and troubleshooting Among these added capabilities a set of diagnostic commands is available Use of these commands to test module interaction is described in the User s Manual Communication Controller Module publication 1771 6 5 15 Even where a computer is connected to the Data Highway however it is recommended that the procedures in this chapter to follow the initial testing of the station Once each station with a programmable controller has been tested operation of computer interfacing can then be checked This section describes the tools available to start up and troubleshoot the system These aids are provided by the module itself by programming terminals and by careful documentation provided by the programmer of the station processor Module Indicators Module diagnostic indicators show the status of module operation with its station processor and with the Data Highway This section describes these indicators and their significan
122. shown in Figure 2 6 or a backplane jumper board assembly cat no 1771 EY A Bulletin 1771 I O chassis is usually mounted within an enclosure We recommend proper grounding of this enclosure because it minimizes the effect of noise from the surrounding industrial environment Grounding procedures for the Bulletin 1771 I O chassis are described in publication 1772 6 6 3 2 0 Chapter 2 Station Hardware Power Supply 2 10 Figure 2 6 1771 AL Adapter Module PLC 2 1 0 ADAPTER 10864 1 1771 KA2 module gets its power from the backplane It requires 5 DC at 1 2 amperes max The following power supplies are compatible System power supply cat no 1771 P1 Auxiliary power supply cat no 1771 P2 PLC 2 system power supply module cat no 1772 P1 series B or later PLC 2 auxiliary power supply cat no 1777 P2 and 1777 P4 series B or later Modular power supplies cat no 1771 P3 P4 P5 You must connect one of these supplies to the I O chassis that contains the KA2 communication adapter module In a Mini PLC 2 or a Mini PLC 2 15 this is the system power supply shown in Figure 2 7 Ina Mini PLC 2 05 you must use a 1771 P3 P4 or P5 power supply Chapter 2 Station Hardware Figure 2 7 1771 P1 System Power Supply Hol CO Battery Low CO ALLEN BRADLEY 108654 When using the PLC 2 20 or PLC 2 30 processor any of these supplies can power the I O chassi
123. sor and checks the communication zone rungs Should proper communication and programming be detected module to processor interaction is resumed and the PROC indicator turns OFF Should both the PROC and PROG indicators be on at the same time turn the mode select switch on the processor to PROGRAM LOAD PROG then back to RUN position to reset module operation Programming Terminals Industrial terminals and program panels are invaluable aids for start up and troubleshooting These devices make available such aids as status indicators value display bit ON OFF status control FAULT bit monitoring and ERROR CODE display For the initial start up procedures described in this chapter it is best to have a least 2 programming terminals available This allows a sending and receiving station to be monitored at the same time Operation and use of the various programming terminals are described in other publications Please refer to the Programming amp Operations manuals in Table 1 B This section briefly reviews the following functions of the programming terminals that have a special importance in troubleshooting testing SEARCH functions a Status indication FORCE functions Each of these tools is used in the procedures of sections titled Start up Procedures and Troubleshooting SEARCH Functions SEARCH functions enable various parts of a program to be quickly located and displayed Table 9 A lists these functions on an ind
124. sy chain e processor or first module in daisy chain Communication Rates e To Data Highway 57 6k baud Recommended e programming terminal or second module 9 6k buad e processor 91 2k baud for processor except PLC 2 cat no 1772 LR 9 6k baud for first communication module or PLC 2 family processor Compatible Power Supplies e System power supply cat no 1771 P 1 e Auxiliary power supply cat no 1772 P2 e System power supply module cat no 1772 P 1 series B or later e Auxiliary power supply cat no 1772 P2 series B or later e Power supply module 1771 P3 e Powersupply module 1771 P4 e Power supply module 1771 P5 Ambient Temperature Rating e 320 to 140 F 0 to 60 C operational e 40 to 1850F 40 85 C storage Humidity Rating e 5 to 95 without condensation Keying e Module slotted for I O chassis keying band positioning e Positions 4 6 22 24 Power Supply Requirement e 45V DC at 12A max This manual uses the term processor as a general term for any of the PLC 2 family processors Individual processors are specified only when some distinction must be made The normal operating sequence of the station processor is not changed by a communication adapter module that is the processor carries out its scan of input and output modules and execution of the user program as though the communication adapter module weren t there l O Chassis Chap
125. t is important that you understand these addresses however to see how they relate to address codes 4 11 Chapter 4 Commands The addressing scheme is summarized in this chart Table 4 A Internal Addressing of a PLC 4 Microtrol Controller Type of Controller Bit Address Address Range Input 0 Output X Flags S Stores Address Number T Timer 5 Timer Clock Enable Timer Timing Done C Counter Count Down Enable Count Up Enable Overflow Underflow Done 1 Flag bits 31 and 32 have a special significance See the PLC 4 Microtrol Product Guide publication 1773 800 The memory map for a PLC 4 Microtrol controller ID 1 shown in Figure 4 4 includes data on inputs outputs and flags of each active controller on the loop Each member of the PLC 4 Microtrol loop including the interface module shares the status of the input output and flag bits for each controller on the loop This becomes significant when you want to determine response time Each time you enter a non privileged command you must enter an address code This becomes significant when you want to determine response time Chapter 4 Commands Figure 4 4 Memory Map for Controller 1 Controller 1 dna inpu Controller 2 1101 1120 Controller 3 A 12 Outputs Inputs Outputs Controller 4 E 0101 0112 and Flags for V ea
126. ta Highway Processor cable connection 4 If the PROG indicator does not turn off after a few seconds observe the ERROR CODE storage word Chapter 9 Start up and Troubleshooting The ERROR CODE storage word is listed in the header rung of the communication zone of program The significance of the ERROR CODE storage word is described in section titled Testing the Receiving Station Correct the communication zone rungs as indicated by the ERROR CODE Then repeat step 3 checking the status of the PROG indicator When the indicators on the station communication adapter module and its station processor show normal operation for both stations being tested perform the procedures of sections titled Testing the Sending Station and Testing the Receiving Station Testing the Sending Station Use the following procedures to test commands from each station After completing these steps for a command verify data transfer at the receiving station as outlined in section titled Testing the Receiving Station The procedures outlined here can be used for any phase of start up and troubleshooting testing and any time a command rung is added at a station processor During initial testing only 2 stations have power on and are connected to the Data Highway cable for these procedures In addition both station processors must be in TEST mode for initial start up testing During later phases of start up testing more than 2 station
127. take a few seconds for the programming terminal to show a change in FAULT bit status Should it be difficult to detect the changing ON OFF bit status for an individual FAULT bit the contact histogram feature can be used to display changes in status 4 From the results of step 3 determine the START bit address for the corresponding command The START bit has a strictly defined correspondence to a REMOTE or LOCAL FAULT bit Figure 6 2 shows this relationship 5 Use the SEARCH functions to locate the command rung that begins with the START bit as determined in the previous step 6 Examine the command code of this rung to determine the remote station number to which the command was sent 7 Determine the nature of the faulted condition and correct this condition Use Figure 9 3 as a guide to tracing possible sources of a faulted condition 8 Verify that the FAULT condition was corrected Observe the fault indicator at the sending station Module Replacement After other troubleshooting checks have been made it may be necessary to replace the communication adapter module Removing the Module 1 Turn off power to the module This power is provided by the power supply that connects to the backplane of the Bulletin 1771 I O chassis 2 Disconnect all cables connected to module sockets 3 plastic latch on the top of the chassis holds the module in place Pivot this latch upward out of the way of the module Chapte
128. tal Decimal Words Chapter 10 Design Aids and Documentation Figure 10 6 Mini PLC 2 05 Memory Organization i Word Bit Decimal Words Address Address Per Area 000 00 N Processor Work Area No 1 16 010 00 Output Image Table 8 QU 17 24 Bit Word Storage 026 17 8 Reserved 027 Factory 64 onfigured C Timer Counter Data i Accumulated Values AC IH or Bit Word Storage Y 40 07 17 72 100 00 Processor Work Area Maximum No 2 T Size of 8 107 17 Data Table 80 110 00 Input Image Table 8 17 17 88 120 00 Bit Word St Storage 8 07 128 130 00 Timer Counter Preset Values PR zt Bit Word Storage 40 1 2944 200 00 Expanded Data Table and or User Program 2816 557717 3072 User Program End of Memory 128 May not be used for accumulated values Not available for bit word storage Bits in this word are used by the processor Unused timer counter memory words can reduce data table size and increase user program area May not be used for preset values Do not use word 127 for block transfer data storage Ma Can be decreased to 48 words 10 7 Chapter 10 Design Aids and Documentation Figure 10 7 Sample Form publication 5030 for Switch Settings on Communication Adapter Module cat no 1771 KA2 ALLEN BRADLEY NINE ROCKWELL INT
129. tatus Words START DONE Word 6 2 Any accessible data table words can be used as status words in the station processor Note that the same recommendations for data table control given in section titled Accessible Data Table Locations PLC 2 Processors chapter 4 should be followed when selecting status words That is processor work areas input image table words and word 027 should not be used as status words The START DONE word is the first of a pair of adjacent status words for communication adapter module use This word stores a START bit and corresponding DONE bit for each of up to 8 commands NOTE should more than 8 command rungs be programmed at a station additional pairs of START DONE and REMOTE LOCAL FAULT words can be used The START bit for any command is always in the upper byte bits 10 17 of the START DONE word The DONE bit for this command is then the corresponding bit in the lower byte bits 00 07 of the same word In Figure 6 1 A the sample command rung examines bit 03210 as its START bit As Figure 6 1 B shows the corresponding DONE bit is bit 03200 Note that the 5 digit address of START DONE bits for each command differs only in the fourth digit the START bit always has a 1 in the fourth digit the DONE bit always has a 0 As its name implies the START bit initiates command execution This bit controlled by the user program is set ON to initiate the sending of a command The communicat
130. ter 2 Station Hardware The interaction between a KA2 module and its station processor occurs in memory control The station KA2 can read data from and write data into processor memory based on various user programmed commands Commands that originate at a station communication adapter module can control only data table areas of processor memory Commands generated by a computer that is connected to the Data Highway through a communication controller module cat no 1771 KE KF can control both data table and user program memory areas Note that the processor continues to execute the user program and to control output devices whether or not the station communication adapter module is in operation Thus disconnection of the Data Highway cable or faulted operation of the communication adapter module does not cause shutdown of the station processor A B designed the 1771 K A2 module to fit in a Bulletin 1771 I O chassis assembly cat no 1771 A1 A2 A4 This chassis houses Mini PLC 2 Mini PLC 2 05 and Mini PLC 2 15 programmable controllers With one of these controllers you can use any unoccupied I O slot for communication adapter modules With PLC 2 20 and PLC 2 30 programmable controllers use a Bulletin 1771 VO chassis as an I O rack In this case the 1771 K A2 module can be installed in any chassis slot except the one furthest left This left most slot must be occupied by a PLC 2 I O adapter module cat no 1771 AL or 1771 AS
131. the first rung the START bit is LATCHED again after the communication adapter module resets the FAULT bit As Figure 7 2 shows the 1771 K A2 module resets a FAULT bit only after the START bit has been turned OFF 7 6 Chapter 7 Command Initiation Execution and Monitoring Even though the FAULT bits are continually reset with this method their usefulness must not be overlooked The section titled REMOTE FAULT Bit Monitoring outlines a useful method to monitor FAULT bits and control an output indicator based on FAULT bit status In some applications it may be useful to send a command continuously between stations With the example of Figure 7 3 this can be accomplished by eliminating the EXAMINE OFF instruction for input 11111 in the second rung This would cause the command to be sent continuously as long as input 11111 remains ON Transition The transition of an input device from ON to OFF and from OFF to ON can be used to LATCH the START bit This allows a command to be sent each time a condition changes state Figure 7 4 shows example rungs for this type of command initiation 7 1 Chapter 7 Command Initiation Execution and Monitoring Figure 7 4 Transition Initiated Command Input Compare Transition 11111 onu 02000 Rung 1 E 1 OFF Input Compare 11111 01111 J H Input Compare 11111 01111 Rung 2 1 5 4 Transi Remote Local tion Fault Fault
132. the standard documentation at each station that uses a programmable controller Forms are available in quantity through Catalog Services Allen Bradley Co Milwaukee Wisconsin 53129 For quick reference a map of the memory organization for each Bulletin 1772 Mini PLC 2 15 PLC 2 30 and Mini PLC 2 05 Programmable Controller is included here These maps should be used in conjunction with the recommendations of chapter 4 concerning communication adapter module access to memory areas Figures 10 2 through 10 6 show the memory organization for each Controller This chapter was provided to help you write organize and document a program for a 1772 K A2 module It reviewed Program summary Forms Memory maps for PLC 2 family processors Chapter 10 Design Aids and Documentation Figure 10 2 PLC 2 20 Processor Memory Organization Octal aros Address sed in Eac Total Decimal Area Word Bit 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 Processor Work Area n 8 8 No 1 00 17 0 0 0 0 1 1 1 0 1 0 0 1 1 0 0 0 010 00 16 Bit PLC 2 20 Word Output Image Table 026 17 24 16 Reserved 027 Additional Outputs 030 00 or Timer Counter i Accumulated Values AC 40 16 Or Bit Word Storage 047 17 Data Timer Counter 050 00 Table AU N aues AC As r Bit Word Storage 64 24 2
133. tina e Australia e Austria e Bahrain Belgium Brazil e Bulgaria e Canada e Chile China PRC Colombia e Costa Rica Croatia e Cyprus e Czech Republic e Denmark Ecuador e Egypt El Salvador e Finland France e Germany e Greece Guatemala e Honduras e Hong Kong Hungary e Iceland India e Indonesia e Israel e Italy e Jamaica e Japan e Jordan e Korea Kuwait e Lebanon Malaysia e Mexico New Zealand e Norway e Oman e Pakistan Peru e Philippines Poland e Portugal e Puerto Rico Qatar e Romania e Russia CIS e Saudi Arabia Singapore e Slovakia e Slovenia e South Africa Republic e Spain e Switzerland e Taiwan e Thailand e The Netherlands e Turkey United Arab Emirates e United Kingdom e United States e Uruguay e Venezuela e Yugoslavia World Headquarters Allen Bradley 1201 South Second Street Milwaukee WI 53204 USA Tel 1 414 382 2000 Fax 1 414 382 4444 Publication 1771 6 5 1 June 1986 PN 955100 16 Supersedes 1771 65 1 March 1985 Copyright 1986 Allen Sradley Company Inc Printed in USA
134. types execution and programming are described in chapters 4 through 7 Each command message causes a reply message to be generated by the receiving station Reply Messages Reply messages are generated by a station in response to command messages that it receives The reply message indicates whether the command message was received and whether the station interface module has completed the sequence of events required of it for command execution For commands that write data the reply message indicates whether the write operation has been completed at the receiving station For commands that read data the reply message contains the data specified by the command If the command was not executed successfully the reply message contains an indication of the error in the STS byte 8 3 Chapter 8 Station Interfacing 8 4 The reply message is an automatic function of communication adapter module operation transparent to the user program To send a reply message a station must have mastership Acknowledgement When a station receives a message addressed to it whether it is a command or reply message the receiving station sends an acknowledgement The acknowledgement is merely a signal that confirms that a message has been received Transparent to the user program the acknowledgement is an automatic function of communication adapter module operation The acknowledgement serves 2 basic functions it indicates that the receivin
135. uld any programming error be detected in the communication zone of program this indicator remains on and module activity on the Data Highway is disabled In this event the ERROR CODE storage word can be checked for an indication of the problem Refer to section titled Start up Procedures for start up procedures Should the PROG indicator fail to run on momentarily at power up or when the mode select switch is turned from PROGRAM LOAD PROG mode the switch selected station number may not match the station number in the header rung of the communication zone of program PROC The red processor link status indicator labeled PROC tells you the status of the module s communication with the station processor This indicator must be off for normal communication Should the PROC indicator go on one of the following problems may have occurred Disconnection of the Data Highway Processor cable which connects the communication adapter module and the processor Power OFF at the processor Fault in processor operation ncorrect processor link communication rate switch selected on the module Refer to section titled Write Option Switch Assembly 9 3 Chapter 9 Start up and Troubleshooting 9 4 Processor troubleshooting is described in the appropriate Assembly and Installation or User s Manual for each controller After the processor fault is corrected the module automatically rechecks its communication with the proces
136. ustrial terminal Chapter 9 Start up and Troubleshooting Table 9 A SEARCH Functions Industrial Terminal Positions cursor on the following program instruction Positions cursor on preceding program instruction Displays previous rung Displays following Displays first rung of program Sen Displays END statement of program Single rung display Press same key sequence to restore multiple rung display XXXXXX The specified instruction is displayed as it appears in one location in the program Press SEARCH to display other locations where this instruction is used XXXX Displays output instructions which control the word xxx or any of its 16 bits After initially pressing this key sequence simply press SEARCH to display each other program location in which word xxx or its individual bits are addressed EXAMINE instructions not displayed by this SEARCH function x gt lt E E L BE r Q 2 e A relay type instruction which addresses a single bit This includes EXAMINE ON EXAMINE OFF OUTPUT ENERGIZE LATCH and UNLATCH instructions An instruction which addresses a three digit word This includes all Timer Counter GET PUT LES EQU IMMEDIATE 1 0 and Arithmetic Instructions Numeric key Bie Status Indication The programming terminals provide a status indication for most program instructions For both the industrial terminal and the PLC
137. wever that the input image table may be read from or written to another station This control restriction applies only when attempting to write data into the input image table using a command from a communication adapter module Word 027 Word 027 has a special function with PLC 2 family processors For example bits 02710 02717 are used for report generation bit 02700 Accessible Data Table Locations PLC Processors Chapter 4 Commands indicates a low battery condition Because of these special functions care must be exercised in controlling word 027 with a write or bit write command The processor does not prevent data from being written to this data table word When it executes a read write or bit write command the communication adapter module controls data table locations at a station processor When addressing a command to a Bulletin 1774 PLC processor note that there are certain data table areas with a special function These data table areas are not to be used for control by communication adapter module commands Any input image table word that has a corresponding input module in a Bulletin 1778 or 1771 I O rack Word 377 Word 000 Input Image Table When an input image table word in the PLC processor data table is unused that is has no corresponding input module in an I O rack that word can be used for storage However should an input module correspond to that word the data in the word is updated fr

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