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1. MBP_GET_NETWORK_STATISTICS Return current statistics from a network controller on the Modbus Plus Network MBP_HOST_WRITEABLE_REGION_V Provides writeable region for each path on a Host SQ85 adapter writeable by a remote master MBP_OPEN_NET Open channels and create paths for the process to access Modbus Plus Network MBP_PRESET_SINGLE_REGISTER Set a single holding register within a PLC on the Modbus Plus Network MBP_READ_GLOBAL_DATA Read the global data from the Host s Modbus Plus controller MBP_READ_REGISTERS Read registers or coils from a PLC on the Modbus Plus Network MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW MBP_READ_UNSOLICITED Dequeue a message from the unsolicited mailbox MBP_REGISTER_UNSOLICITED Register for unsolicited slave messages from PLCs or other VAXs on the Modbus Plus Network Allocate a mailbox and initiate the actual posting and functioning of the slave data path reads and responses MBP_REGISTER_UNSOLICITED_V Register for unsolicited slave messages from PLCs or other VAXs on the Modbus Plus Network Allocate a mailbox for each path of the SQ85 and initiate the actual posting and functioning of the slave data path reads and responses MBP_WRITE_GLOBAL_DATA Write to the host controller s global data MBP_WRITE_REGISTERS Write a group of registers or coils ina PLC on the Modbus Plus Network MBP_READ_EXTENDED Read registers from extended memory files in PLC MBP_SUSPEND_UNSOLICITED Suspend
2. 10374 Last write 3 0 000000 Start of read 4 MAY 1994 11 29 19 28 Write Read counter 0 0 Start of write 4 MAY 1994 11 29 19 30 Start of read Avg time master read 0 027727 Start of write Avg time master writes 0 037956 Avg time slave reads Avg time slave writes From the display the following can be determined The process has allocated master path number two The last condition code was successful The size of the last transfer was twenty bytes The time of the Modbus Plus read or writes The average time for a master read or write to complete total time for the master write plus the response from the addressed slave The time for the last master read or write How many master writes and reads have been done by the process 66 Appendix A Header Files MODBUS Plus VMS INTERFACE LIBRARY Header Files A IMBPPEX Structure The following structures are provided in the include library 1 slave h Definition of the message placed in the unsolicited message mailbox 2 mbp_errors h Definition of all MBP error codes this does not include those from the Modbus Plus communication device driver 3 mbp_status h Standard status block returned from most calls that require I O to the Modbus Plus network 68 Appendix B MBP Error Codes MODBUS Plus VMS INTERFACE LIBRARY ERROR CODES The MBP software has the errors listed below along with the recovery procedures The user should also consult the Modbus Plus Dev
3. 36 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 11 MBP READ GLOBAL DATA Read the 64 bytes of global data FORMAT BP_READ_GLOBAL_DATA MBPPEX PATH NODE BUFFER EFN STATUS RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MBP_ error status codes ARGUMENTS MBPPEX type structure access readonly mechanism by reference Structure returned by MBP_OPEN_NET PATH type word access readonly mechanism by value Path that this I O is to be directed to This path number must be between one and the number allocated by the MBP_OPEN_NET call NODE type word access readonly mechanism by value The Modbus Plus node the global data is requested of BUFFER type array access write mechanism by reference Contains the buffer to recieve this controller s global data area 37 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS EFN type long word access readonly mechanism by value T O event flag for synchronization STATUS type structure MBP_STATUS access write mechanims by reference V O completion status DESCRIPTION This subroutine will read the 64 bytes of global data This routine operates synchronously as the data is local in the computer s controller No byte swapping is to the data that is written to the controller The Modbus Plus global data is mai
4. type structure access write mechanism by reference The structure to receive the starting and ending address of the process specific data area used by the Modbus Plus interface subroutines see MBPPEX in MBPlus TLB DEVICE type character access read only mechanism by descriptor This specifies the name of the Modbus Plus interface MPA1 MPB1 MPC1 or MPD1 MASTER_PATHS type word access read only mechanism by value This specifies the number of progam master paths the caller desires to allocate for its use Depending on the controller there are a certain number of paths available to be used See Modbus Plus documentation for a description of PATH If the entire number of paths specified cannot be allocated then none are allocated MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS DESCRIPTION This subroutine open channels and allocates Modbus Plus Program Master paths to be used for communicating with the Modbus Plus network This subroutine expands the callers PO space to allocate working storage for future calls to the Modbus Plus network The structure MBPPEX that is returned to the user must be passed on all subsequent calls to the other Modbus Plus software interface routines This is normally the first call by the user application software This routine provides Program Master versus Data Master paths This routine is used normally for diagnostic programs where the data paths are all being us
5. word access readonly mechanism by value The number of packed registers to read from the addressed PLC If the number of registers exceeds what is able to read from a single Modbus Plus transfer multiple Modbus Plus transfers will be done FILE type word access readonly mechanism by value The extended memory of the PLC is broken up into 10000 registers each and the remaining amount for the last segment allowing registers in the range of 60000 to 69999 per file The file number ranges from one 1 to the available memory assigned in the PLC for extended memory in ten thousand register increments BUFFER type array access write mechanism by reference Caller array to receive the registers from the PLC STATUS type structure MBP_STATUS access write mechanism by reference Final status EFN type long word access readonly mechanism by value Event flag to set when I O is complete FLAG type long word access readonly mechanism by value If non zero then the data is not byte swapped when it is placed into the caller 35 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS MTMO type long word access read mechanism by value Modbus Read Master Response timeout value in seconds Must be greater than two DESCRIPTION This subroutine reads the registers from the extended memory files in the slave PLC on the Modbus Plus network The data is byte swapped unless the
6. 33 36 39 42 45 60 63 66 75 MBP_PROGACCESSDENIED 77 MBP_READ EXTENDED Defined 34 MBP_READ_EXTENDEDW Defined 34 MBP_READ_GLOBAL_DATA Defined 38 MBP_READ_REGISTERS Defined 40 MBP_READ_REGISTERSW Defined 40 MBP_READ_UNSOLICITED 48 MBP_REGISTER_UNSOLICITED 25 27 44 MBP_RESUME_UNSOLICITED Defined 53 MBP_SLAVEDOWN 77 MBP_SLAVEFAIL 76 MBP_SLAVEREJECT 77 MBP_SLVBUSY 73 MBP_SLVREADFAIL 75 MBP_SLVREADQIO 76 MBP_SLVRSPFAIL 76 MBP_SLVRSPQIO 76 MBP_STATUS 12 71 MBP_SUSPEND_UNSOLICITED Defined 55 MBP_UNKRTRERR 77 MBP_UNSUPPORTED 77 MBP_WRITE_EXTENDED Defined 58 MBP_WRITE_EXTENDEDW Defined 58 MBP_WRITE_GLOBAL_DATA Defined 62 MBP_WRNGNMBRPATHS 75 MBPLUS_Logical 5 Modbus Routing 6 Object Library 5 Path 8 Path Allocation 8 PLC Register Addressing 6 Process Expanded Region 12 Process Global Section 68 Process Quotas 6 Process Region 27 30 Required Privileges 5 Routing 6 Slave Paths 9 11 Status Block 11 SYS SNDOPR 73 VAX Slave Paths 11 Index VMSINSTAL 85
7. FLAG byte is set to one This routine make use of the Modbus function code 20 This routine is available in both the asynchronous and synchronous versions By default the bytes are byte swapped when they are recieved from the PLC unless the FLAG argument is specified The user call may translate into multiple I Os to the selected Modbus Plus device The event flag will be set when all of the I O is complete or an error is encountered The starting register number for an extended memory file registers is one less than for the other registers the first register in an extended memory file is 60000 while the first holding register is 40001 Each extended memory file is partitioned to hold 10000 registers except for the last file which occupies whatever is left in the extended memory Only a single extended memory file may be written per call CONDITION VALUES RETURNED MBP_MBPPEXINVLD MBP_INVALIDARG MBP_IONOTCOMP MBP_NOCHANNEL MBP_BADSTARTADDR MBP_PATHINUSE MBP_INVALIDEFN MBP_NOTINITIALIZED MBP_BADPATH MPB_INVLPATH MBPPEX structure is invalid One of the call arguments is invalid not readable or not writable T O not complete on channel No channel open on path Invalid starting address The specified path already has an I O active Invalid event flag specified MBPPEX structure not initialized Path specified not allocated or out of range Specified path is not between one and the number allocated by MBP_OPEN_NET
8. I 34 INT INT t J I I 01008 01009 01007 01003 I I I MSTR I DO MSTR I 44 t I 01003 I I MSTR STOP I MSTR MAX FAIL I DONE BAD EXCEEDED I 54 JPI amp x I 01009 00999 01012 I I MSTR I MSTR FAILURE I DONE GOOD CNT ACCUM I 64 INT tUCTR I 01008 40511 I Kos tal 78 MODBUS Plus VMS INTERFACE LIBRARY EXAMPLES NETWORK 0008 Segment 01 When an MSTR instruction execution terminates successfully DONE GOOD is set and sealed in When an MSTR instruction execution terminated unsuccessfully DONE BAD is set and sealed in When the MSTR instruction terminates DONE is set I I MSTR MSTR STR I SUCCESS RESET DONE GOOD I 1 P I 01006 01002 01008 I I I MSTR I DONE GOOD I 2 I 01008 I I I MSTR MSTR MSTR I FAILURE RESET DONEBAD I 3 P t 35 I 01005 01002 01009 I I I MSTR I DONE BAD I 4 I 01009 I I I MSTR MSTR I DONE GOOD DONE I 54 H I 01008 01007 I I I MSTR I DONE BAD I 6 I 01009 I 79 MODBUS Plus VMS INTERFACE LIBRARY EXAMPLES NETWORK 0009 Segment 01 The MSTR instruction is allowed to execute when DO MSTR is set until DONE is set DONE is set when the MSTR instruction terminates see the comment for network 8 When the MSTR instruction is executing ACTIVE is set The MSTR control block regist
9. function for the addressed slave 02 Illegal data address within the information field ofr the addressed slave 03 Illegal data value in the information field for the addressed slave Also if the master requests a QIO call with too large a buffer 06 Busy the function just requested cannot be performed at this time because a long duration program command is beind processed MBP_INVALIDARG Invalid argument One of the user passed arguments is invalid MBP_INVALIDEFN Invalid event flag specified An event flag has been specified that is not valid Consult the VMS system service manual for valid event flag useage MBP_INVALIDEFN Invalid event flag specified The event passed is an invalid VMS event flag Consult the VMS system service manual for the correct usage of event flags MBP_IONOTCOMP VO not complete on channel User has attempted to requested another function on a path that has not completed the prior request MBP_MAPFAIL Unable to create process region The MBP_OPEN_NET failed to create the group global section The most probable error is insufficient privilege Examine the mbp I_status in the MBPPEX structure MBP_MBXCREFAIL Unable to create slave data mailbox The register unsolicited was unable to create the mailbox Examine the mbp I_status in the MBPPEX structure for the reason Most probable are insufficient privilege or insufficient buffer quota MBP_MBXSIZE Specified mailbox is too small 71 MODBUS Plus VMS INTE
10. routine simply clears the disable bit in the region for the slave path requested The slave paths are the controller slave path numberes as allocated by the driver and referenced by the SQ85 This is the second parameter in aPLC MSTR route information in the programmable controller CONDITION MBP_NOSLAVE No slave paths were allocated VALUES RETURNED MBP_MBXFAIL Unable to create mailbox see secondary status will contain the VMS system service code MBP_NOSUCHPATH The desired slave path was not allocated to the target process MBP_NOSLAVEMATCH Controller slave path was assigned by process 53 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 17 _MBP_SUSPEND_ UNSOLICITED Stop the recognition of Modbus Plus slave messages of a Modbus Plus connected VMS process FORMAT MBP_SUSPEND_UNSOLICITED MBPPEX PROCESS_NAME DEVICE CTRL_SLAVE_PATH RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access read mechanism by reference The structure to receive starting and ending address of the process specific data area used by the Modbus Plus interface subroutines see MBPPEX in MBPlus TLB PROCESS_NAME type character zero terminated access readonly mechanism by reference Process name of the target process DEVICE type c
11. source code or RMS keyed files 1 5 PLC Registers and Coil Numbering All of the calls provided by the Modbus Application Library use the same numbering system as the actual PLC itself The user need not bias or normalize any of the registers or coil number before passing the register address to the subroutine This allows the PLC programmer and the VAX programmer the ability to converse using identical register and coil numbers The software examines the address such as 40001 and knows that this is the first holding register or 00001 is the first coil status MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW 1 6 PLC MSTR Blocks The PLC MSTR requires a routing path and a Modbus Plus function code along with other parameters The routing path specifies the target slave node that can be another PLC or the VAX If the target is a VAX then the PLC must also specify in the next route register the host data slave path the message is to be sent to The preferred method for mapping the slave data paths and VAX Host node addresses is to have the VAX hosts specify these parameters to the PLC in its holding registers or global data area By using this methodology the PLC does not need to maintain this part of the link management This has the following benefits o The programmers of the PLC need not worry about communicating changes to the programmers of the VAX unless agreed upon locations of the link management registers are changed o The ability
12. that has not completed the prior request 72 MODBUS Plus VMS INTERFACE LIBRARY ERROR CODES MBP_SLAVEFAIL Slave read I O failure XL XL master XB gt This error is logged on the system console It is generated by the AST services for the unsolicited messages Examine the I O status displayed and consult the Modicon DEC host Based Devices User s Guide MBP_SLVASSIGNED Slave path already assigned for unsolicited messages The caller has tried to register for unsolcited reads master writes from a PLC a second time MBP_SLVBUSY Attempt to allocate second read on same slave path A second MBP_REGISTER_UNSOLICITED was attempted to the same controller MBP_SLVREADFAIL Slave read failure The register unsolicited attempted to post a read on the slave paths but failed Examine mbp I_status for system service or Modbus Plus device error codes MBP_SLVREADQIO Error posting IO READ_SR status XL This error is logged on the system console It is generated when the HOST is attempting to post a read on one of the slave data paths Examine the I O status displayed and consult the Modicon DEC Host Based Devices User s Guide MBP_SLVRSPFAIL Slave response I O failure XL XL This error is logged on the system console It is generated when the VAX host attempts to acknowledge the write of the holding registers to the VAX Examine the I O status displayed and consult the Modicon DEC Host Based Devices User s Guide MBP_SLVRSPQIO Error po
13. BYTE PAGEF BYTE SEGMENTS WORD CONTROLLER STATUS WORD STOP CODE DESCRIPTION This routine asks a particular Modbus Plus node to return its id The user buffer should 9 bytes long For more information see the Modbus Plus Device Drivers Manual under function code 11 This call is synchronous The format of the controller status word is 1 111 110 000 000 000 5 432 109 876 543 210 III Lit lll II Memory downsized 0 no 1 yes lll II Unassigned t Battery Status 0 ok 1 not ok emory Protect 0 on 1 off Run indicator 0 on 1 off Power on 1 on 0 off IE RI EN Processor size 1 16 bit node 0 24 bit node Harelolelnoenn Single sweep status 0 off 1 on DEE ER eee Constant sweep status 0 off 1 on Gite he ek a Een er SE Unassigned MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS The format of the stop code word is Real Time Watch Dog 0 000 000 000 5 432 109 876 543 210 I III 11 Illegal configuration II III Coil disabled while in RUN mode II III Logic checksum error Invalid node type S908 remote I O head failure CPU diagnostic failed Clock error Timer expired No end of logic detected or bad quantity of segments Stare ram test failed f Node did not start segment ment scheduler table Bad seg intervention Illegal Ext
14. K_UNSOLICITED_MSGSIZE unless the caller has set up this in the MBP_REGISTER_UNSOLICITED_V call SS _BUFFEROVF User buffer was not large enough to contain the complete message 44 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 14 MBP REGISTER UNSOLICITED Establish mailbox for a Master Modbus Plus nodes to write to FORMAT MBP_REGISTER_UNSOLICITED MBPPEX MBX_NAME MSG_CNT PERM MBX_CHANNEL HOLDING_ REGISTERS NUMBER_HOLDING_REGISTERS RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access write mechanism by reference The structure to receive starting and ending address of the process specific data area used by the Modbus Plus interface subroutines see MBPPEX in MBPlus TLB MBX_NAME type character access read only mechanism by descriptor Specifies the name of the mailbox to be created or a channel assigned to MSG_CNT type word access read only mechanism by value This specifies the number of messages that should be allowed to be queued in the mailbox This affects the buffer I O quota for the process PERM type word access read only mechanism by value This specifies if the mailbox should be established as a permanent mailbox A permanent mailbox will allow messages to be retained over proce
15. L Unable to assign device MBP_PATHFAIL Unable to allocate a path 30 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 9 MBP_PRESET_SINGLE_ REGISTER Set a single Programmable Controller register FORMAT MBP_PRESET_SINGLE_REGISTER W MBPPEX PATH ROUTE REGISTER_NUMBER VALUE STATUS EFN MTMO RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MBP_ error status codes ARGUMENTS MBPPEX type structure access readonly mechanism by reference Structure returned by MBP_OPEN_NET PATH type word access readonly mechanism by value Path that this I O is to be directed to Must be between one and the number master paths allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference This is an array filled in by the caller that specifies the route path to the particular PLC The content of this array requires knowledge of the connected Modbus Plus network devices and their addresses This subroutine does not validate the route array REGISTER_NUMBER type longword access readonly mechanism by value The register number to force in the addressed PLC 40001 to 49999 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS VALUE type word access readonly mechanism by value New value for the register in normal VMS VAX 16 bit word format The data will be by
16. LICATION LIBRARY CALLS MTMO type long word access read mechanism by value Modbus Read Master Response timeout value in seconds Must be greater than two DESCRIPTION This subroutine writes registers in extended memory files in slave PLCs on the Modbus Plus network The data is byte swapped unless the FLAG argument is set to one This routine makes use of the Modbus function code 21 This routine is available in both the asynchronous and synchronous versions By default the bytes are byte swapped when before they are written to the PLC unless the FLAG argument is specified The user call may translate into multiple I Os to the selected Modbus Plus device The event flag will be set when the all of I O is complete or an error is encountered The starting register number for an extended memory file registers is one less than that for the other registers the first register in an extended memory file is 60000 while the first holding register is 40001 Each extended memory file is partitioned to hold 10000 registers except for the last file which occupies whatever is left in the extended memory Only a single extended memory file may be written per call CONDITION MBP_MBPPEXINVLD VALUES RETURNED MBP_INVALIDARG MBP_PATHINUSE MBP_BADPATH MBP_NOCHANNEL MBP_BADSTARTADDR MBP_IONOTCOMP MBP_NOTINITIALIZED MBP_INVALIDEFN MPB_INVLPATH MBPPEX structure is invalid One of the call arguments is invalid not readable or n
17. MBP_GET_NETWORK_STATISTICS 25 MBP_GET_SLAVE_ID 2 6 MBP_HOST_WRITEABLE_REGION_V 2 7 MBP_OPEN_NET N ANNanAnbP HRN 11 11 12 12 12 13 14 15 18 19 21 24 26 Table of Contents 2 8 MBP_OPEN_PROGMASTER 2 9 MBP_PRESET_SINGLE_REGISTER 2 10 MBP_READ_ EXTENDED 2 11 MBP_READ_GLOBAL_DATA 2 12 MBP_READ_REGISTERS 2 13 MBP_READ_UNSOLICITED 2 14 MBP_REGISTER_UNSOLICITED 2 15 MBP_REGISTER_UNSOLICITED_V 2 16 MBP_RESUME_UNSOLICITED 2 17 MBP_SUSPEND_UNSOLICITED 2 18 MBP_WRITE_EXTENDED 2 19 MBP_WRITE_GLOBAL_DATA 2 20 MBP_WRITE_REGISTERS CHAPTER 3 UTILITIES 3 1 Introduction 3 2 Network Diagnostic Utility 3 3 Monitor Modbus Plus Process APPENDIX A HEADER FILES A l MBPPEX Structure APPENDIX B MBP ERROR CODES B 1 MBP Error Codes B 2 Routing Errors APPENDIX C SAMPLE PLC MSTR C 1 MSTR Example APPENDIX D EXAMPLE VMSINSTALL D 1 VMSINSTALL Example 29 31 34 37 39 42 45 49 52 54 56 59 61 64 65 65 65 67 68 69 70 74 75 76 81 82 Chapter 1 MODBUS Plus VMS Interface Library MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW 1 1 Introduction This document describes the Modbus Plus interface library and its distribution with the Modbus Plus Device Driver for VAXVMS for the SQ85 licensed by Modicon or the Modbus Plus Device Drdiver for AXPVMS for the SA85 licensed by IPACT This document also provides some integration help in using this software alon
18. OR 1 READ_WRITE_REGISTERS_EX COM 1 READ_WRITE_REGISTERS_EX EXE 1 READ_WRITE_REGISTERS_EX FOR 1 REGISTER_UNSOLICITED_EX COM 1 REGISTER_UNSOLICITED_EX EXE 1 REGISTER_UNSOLICITED_EX FOR 1 RW_EXTENDED_EX COM 1 RW_EXTENDED_EX EXE 1 RW_EXTENDED_EX FOR 1 SCAN COM 1 SCAN FOR 1 SMG_DISPLAY FOR 1 SYS_ERROR FOR 1 Total of 34 files 85 Index INDEX Byte Order 11 Byte Swapping 11 66 Console Messages 73 Data Representation 11 Debug Library 5 Dedicated Slave Paths 11 DSPMBP 68 Host 12 Host Holding Registers 46 Linker 5 Linking Requirements 5 Master Paths 8 MBP_ASSIGNFAIL 74 MBP_BADDESTADDR 77 MBP_BADPATH 23 32 39 45 63 75 MBP_BADSTARTADDR 75 MBP_BRIDGEBUSY 77 mbp_bufdef h 44 MBP C 12 MBP_CLOSE_NET Defined 14 MBP_EXCEPTION 75 MBP_EXCEPTIONRESPONSE 77 MBP_FOR 12 MBP_FORCE_SINGLE_COIL Defined 15 MBP_FORGOTTEN 77 MBP_GET_NETWORK_STATISTICS Defined 19 MBP_GET_SLAVE_ID Defined 21 MBP_INVALIDARG 66 76 MBP_INVALIDROUTE 77 MBP_INVLPATH 37 42 61 66 MBP_IONOTCOMP 33 74 MBP_MAPFAIL 77 MBP_MBPEXINVLD 36 42 60 66 MBP_MBXCREFAIL 75 MBP_MBXFAIL 49 52 MBP_MBXSIZE 52 MBP_MBXWRITFAIL 75 MBP_NOCHANNEL 23 33 39 45 63 74 MBP_NODEOFFLINE 77 MBP_NORRESPONSE 77 MBP_NOSLAVE 25 48 52 54 56 74 MBP_NOSLAVEMATCH 54 57 MBP_NOSUCHPATH 54 56 MBP_NOTINITIALIZED 23 32 39 45 63 74 MBP_NVALIDPATH 77 MBP_OPEN_NET Defined 26 29 MBP_PATHFAIL 73 MBP_PATHINUSE 23
19. RFACE LIBRARY ERROR CODES The specified mailbox size for slave reads PLC master writes is too small It must be at least as large as the Modbus Plus header size MBP_MBXWRITFAIL lt MBX failed ios XL syssts XL size XL Failed to write Modbus slave message to the unsolicited mailbox Examine the status and determine recovery MBP_NOCHANNEL No channel open on path The user has passed a path that has no channel assigned to the MPAI device The most probable cause is that not all of the user s requested paths were allocated by the MBP_OPEN_NET call MBP_NOSLAVE Caller did not allocate any slave paths The user has requested to provide slave service but no slave paths were allocated by the MBP_OPEN_NET call Either none were available or the MBP_OPEN_NET call is in error MBP_NOSLAVEMATCH Controller slave path was not assigned The current process has not set up the VAX for unsolicited reads for the indicated path The path number may be in error or the call has not correctly registered for slave messags MBP_NOTINITIALIZED MBPPEX structure not initialized The user has not called MBP_OPEN_NET the MBPPEX structure is corrupt or the MBPPEX was passed incorrectly MBP_PATHFAIL Unable to allocate a path The MBP_OPEN_NET was unable to open the number of paths as requested by the caller Examine the mbp l_status in the MBPPEX structure MBP_PATHINUSE Path is in use User has attempted to requested another function on a path
20. TAL kit uses the current version and revision numbers to create a unique software distribution directory e g SYS COMMON MBP017 The software is placed in the root of SYS COMMON or SYS SYSDEVICE 1 3 2 _Compile Requirements The following text libraries are available in the kit directory These libraries contain the Modbus Plus I O codes and structures required for accessing the Modbus Plus application library These libraries are MBPLUS_ MBP_C TLB C header definitions MBPLUS_ MBP_FOR TLB FORTRAN structure definitions The following are contained in these libraries e MBPPEX The process expanded region created by the MBP_OPEN_NET service e MBPSHARE_MSG Definition of all error codes returned by the Interface Communications library e MP_FUNCS Definition of the VMS I O function codes for the Modbus Device Driver e MBP_DEF DECC Function prototypes for all of the MBP_ functions available only on OPEN VMS AXP e MPDRIVER_MSG Definition of all error codes returned by the MPDRIVER for OPEN VMS AXP for theSA85 device For C programmers the user should compile and link with the following command assuming source module is test c CC test mbplus_ mbp_c tlb library For FORTRAN programmers the user may specify the location of the text library in the include statement within the source module MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW 1 3 3 Linking Requirements The user has a choice of linking to either a shared
21. This routine probes the holding register array for read access The byte order and synchronization of data within the Host Holding Register region are the responsibility of the user The VMS process that calls MBP_REGISTER_UNSOLICITED supports the actual data transfer between the Modbus Plus device driver at AST level Therefore disabling the AST recognition of this VMS process while the region is being modified will guarantee atomic and consistent data for Modbus Plus Master nodes reading data from the Host s holding registers The method used must ensure that the process will be able to respond to the Master Modbus Plus node prior to the Master node timing out because no slave data response from the VMS host was received 47 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS CONDITION MBP_NOSLAVE No slave paths were allocated VALUES RETURNED MBP_NOTINITIALIZED MBPPEX structure not initialized MBP_SLVREADFAIL Slave read failure MBP_SLVBUSY Attempt to allocate second read on same slave path MBP_MBXCREFAIL VMS SYS CREMBX failed Examine MBP L_STATUS in the MBPPEX structure for the System Service status MBP_MBXFAIL Unable to create mailbox see secondary status will contain the VMS system service code 48 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 15 MBP REGISTER UNSOLICITED V Establish mailboxes for Master Modbus Plus nodes to write to by slave path Similar to MBP_REGISTER_UNSOLICITED but u
22. VMS VAX AXP Modbus Plus Interface Library Programmer s Manual Release 1 9 Copyright 1994 1996 1997 Integrated Process Automation and Control Technologies Incorporated All rights reserved No part of this publication may be reproduced stored in a retrieval system or transmitted in any form without written permission by IPACT Inc Technical Writer Earl D Lakia Senior Staff Engineer IPACT Inc The following are trademarks of Digital Equipment AXP VMS DEC VAX The following are trademarks of Modicon Modbus Plus SA85 and SQ85 The IPACT is a trademark of Integrated Process Automation and Control Technologies Incorporated file k ipemv3 ipecommon mbplus user_doc library doc 8 19 99 Table of Contents CHAPTER 1 MODBUS PLUS VMS INTERFACE LIBRARY 1 1 Introduction 1 2 Interface Library 1 3 Shareable Image Entry Points 1 3 1 Installation 1 3 2 Compile Requirements 1 3 3 Linking Requirements 1 3 4 Example Programs 1 3 4 1 Process Privileges 1 3 4 2 Process Quotas 1 4 Modbus Network 1 5 PLC Registers and Coil Numbering 1 6 PLC MSTR Blocks 1 6 1 PLC MSTR Example 1 7 Paths 1 8 Master Paths 1 9 Slave Paths 1 10 Non PLC Modbus Nodes 1 11 VAX and PLC Data Byte Order 1 12 Application Status Returns 1 13 Contention and Synchronization Issues 1 14 Process Expanded Region CHAPTER 2 MBP APPLICATION LIBRARY CALLS 2 1 MBP_CLOSE_NET 2 2 MBP_FORCE_SINGLE_COIL 2 3 MBP_GET_DRIVER_STATISTICS 2 4
23. VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below The final status on a normal successful call is the status returned from the SYS QIO call to the Modbus Device driver ARGUMENTS MBPPEX type structure access readonly mechanism by reference The structure that was returned by the MBP_OPEN_NET call PATH type word access readonly mechanism by value Path that this I O is to be directed to Must be between one and the number allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference This is an array filled in by the caller that specifies the route path to the particular PLC The content of this array requires knowledge of the connected Modbus Plus network devices and their addresses COIL_NUMBER type word access readonly mechanism by value The coil number to force in the addressed PLC MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS STATE type word access readonly mechanism by value New state of the coil 0 or 1 STATUS type structure MBP_STATUS access write mechanism by reference Final completion status as returned by the Modbus Plus device driver See QIO condition codes in Modicon DEC Host Based Devices User s Manual EFN type long word access read mechanism by value Event flag to s
24. ZE The minimum size must be larger than size of the modbus message header Mbx channel type long word access write This is the returned channel number of the created or assigned mailbox Each path is assigned to a unique mailbox The caller passes the name of each mailbox and if the mailbox should be permanent or not If the mailbox is permanent the letter count and letter size will not be used if the mailbox already exists on a subsequent activation of the process The caller must have already allocated slave paths via the MPB_OPEN_NET call This subroutine will post reads on each of the slave paths and write the messages to the mailbox when the messages are received In the event the mailbox becomes full the software will respond to the remote device with the Modbus Plus slave response indicating a routing error response The routing failure code will be set to indicate 10 Slave rejected command If the mailbox is to be created as a permanent mailbox the caller must have SYSNAM privilege The reading process can be either the current process or any other process in the system The actual content of the letter contained in the mailbox is documented in the Modicon DEC Host Based Devices User s Guide under the IO _READ_SC command The complete message including the Modbus Plus header is placed into the mailbox The actual format of the data portion of the message has to be defined with the programmer of the PLC sending Ma
25. _NET most likely failed to allocate all of the desired paths Check status of the MBP_OPEN_NET call MBP_IONOTCOMP Previous I O still outstanding on path 33 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 10 MBP READ EXTENDED Read Extended Memory of a Slave Modbus Node FORMAT MBP_READ_EXTENDED W MBPPEX PATH ROUTE START COUNT FILE BUFFER STATUS EFN FLAGL MTMO RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access readonly mechanism by reference The structure that was returned by the MBP_OPEN_NET call PATH type word access readonly mechanism by value Path that this I O is to be directed to The path must be between one and the number allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference This is an array filled in by the caller that specifies the route path to the particular PLC The content of this array requires knowledge of the connected Modbus Plus network devices and their addresses START type long access readonly mechanism by value Starting register in addressed PLC to beginning reading registers from Valid range for each file is 60000 to 69999 34 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS COUNT type
26. a process from receiving any further modbus slave messages for a particular path on a SQ85 host adapter MBP_RESUME_UNSOLICITED Resume a process to receive further modbus slave messages for a particular path on a SQ85 host adapter MBP_WRITE_EXTENDED Write registers to extended memory files in PLC Each of the above mentioned calls are documented in Chapter Two Certain calls may be called to wait for the communication to complete by specifying a valid event flag and using the W call e g MBP_WRITE_REGISTERSW Most calls allow only a single function on a path to be active at a time This is due to the design of the Modbus Plus network protocol MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW 1 3 1 Installation This software is implemented as a shared executable library a linkable object library is also supplied but usage should be discouraged This method provides the ability to install new releases of the software without requiring the applications that use them to be recompiled or relinked This software and the VMS device driver for the SQ85 or SA85 network controller is installed via VMSINSTAL A sample VMSINSTAL session is included in the appendix After installation the logical MBPLUS_ points to the directory of the installed software The command file MBP_STARTUP COM should be chained to by the system or application startup command procedures MBP_STARTUP will define the logical names and install the shared library The VMSINS
27. a single controller if desired using a unique MBPPEX structure for each controller All master paths are allocated by the driver The slave paths are allocated starting with one unless the optional parameter ctrl_paths is present indicating the associated actual SQ85 controler slave paths to allocate for each path The master and slave paths allocated may or may not start with master path one It is possible that some but not all of the master or slave paths could not be allocated Therefore if this routine fails the caller should do its normal error recovery and then exit The actual master and slave paths allocated are stored in the process expanded region returned in the MBPPEX structure and may be viewed with Modbus Plus process monitor utility CONDITION MBP_WRNGNMBRPATHS Wrong number of paths VALUES RETURNED MBP_MAPFAIL Unable to create process region 27 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS MBP_ASSIGNFAIL Unable to assign device MBP_PATHFAIL Unable to allocate a path 28 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 8 MBP_OPEN_PROGMASTER Enable Modbus Communications using Program Master Paths FORMAT MBP_OPEN_PROGMASTER MBPPEX DEVICE MASTER_PATHS RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX
28. array of Quad word descriptors access readonly mechanism by reference This structure should be dimensioned by eight number of modbus slave paths An entry should be filled in for each slave path allocated in the MBP_OPEN_NET call Each quad word entry contains a standard VAX VMS descriptor only length and address are used DESCRIPTION This subroutine allows the caller to set up a region to receive slave messages from devices on the Modbus Plus network Each path can be assigned to a unique region The caller must have already allocated slave paths via the MPB_OPEN_NET call The user passes a descriptor see VMS documenatation for this datatype for each slave path the caller wants to be mapped to a region The regions may be identical The service probes to ensure that the reason is accessible for write in the access mode of the caller The passed addresses for the regions may the either process private group global or system global regions Additionally they may all map the same address space if desired No locking is provided to protect the region from master writes or reads by the remote Modbus Plus nodes The service determines the length of the region from the descriptor and uses this to determine if a master read or write request from the remote Modbus Plus node is valid A Modbus Plus execption is sent to the remote Modbus Plus Master node if the requested holding register is out of range All regions are mapped as if the firs
29. ception of slave messages from a PLC master see MBP_RESUME_UNSOLICITED and MBP_SUSPEND_UNSOLICITED 12 Chapter 2 MBP Application Library Calls MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 1 MBP CLOSE_ NET Disconnect Modbus Plus Network FORMAT MBP_CLOSE_NET MBPPEX RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access read write mechanism by reference The structure that was returned by the MBP_OPEN_NET call DESCRIPTION This subroutine will deassign the channels and deallocate the paths that were used for communicating with the Modbus Plus Network by the calling process The process expanded PO space that was allocated is deleted along with the group global section This routine does not need to be called if the process is exiting as the normal VMS V O rundown will release all paths and channels that were allocated by the process CONDITION MBP_NOTINITIALIZED MBPPEX structure is invalid VALUES RETURNED SYSTEM SERVICE Errors from SYS DEASSIGN SYS QIO SYS DELTVA MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 2 MBP FORCE SINGLE COIL Force a single output coil FORMAT MBP_FORCE_SINGLE_COIL MBPPEX PATH ROUTE COIL_NUMBER STATE STATUS EFN MTMO RETURNS
30. croVAX II running VMS V5 4 2 Username SYSTEM Password Welcome to VAX VMS V5 4 2 set def sys update vmsinstal VAX VMS Software Product Installation Procedure V5 4 2 It is 15 OCT 1992 at 08 06 Enter a question mark at any time for help 7 VMSINSTAL W ACTIVE The following processes are still active LAKIA Do you want to continue anyway NO y Are you satisfied with the backup of your system disk YES y Where will the distribution volumes be mounted MUAO Enter the products to be processed from the first distribution volume set Products mbp012 Enter installation options you wish to use none The following products will be processed MBP V1 2 Beginning installation of MBP V1 2 at 08 07 VMSINSTAL I RESTORE Restoring product save set A Modbus Application Interface Library and Software Installation By IPACT Inc Modbus Communications Device Driver By Modicon The distribution files have been restored from the saveset The installation procedure is continuing Your system or common device directory IPACT DUAO0 SYS0 S YSCOMMON This product creates the directory IPACT DUAO0 SYS0 SYSCOMMON MBP012 82 MODBUS Plus VMS INTERFACE LIBRARY INSTALLATION There appears to be an old version of the software installed in your system There is an old version currently installed in your the system This will prevent us from doing the Installation Verification Procedure You may choose abort this instal
31. e PLCs and the allocated data paths into the 40004 holding registers In the event of a failure of one of the VAXs the failed application would begin execution on the other VAX we assume a clustered or shared type of VAX MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW environment In this case the appropriate holding registers would be loaded to direct all of the MSTR blocks to the correct VAX During the time between when a VAX failed and the application was restarted on the BACKUP VAX the MSTR blocks would terminate unsuccessfully User written logic might choose to zero the VAX node and data path bytes and not execute the MSTR block until both are non zero again The zeroing of the node and data path in the MSTR route holding registers may be triggered by five or ten consecutive errors from the MSTR block The MSTR would be reenabled when the backup VAX wrote the new node and path to the holding registers A sample PLC program is shown in the appendix 1 7 Paths Communication that actually requires datagrams over the Modbus Plus network require a path Depending on the type of node the number of paths differ A path can be considered like an end to end socket that two Modbus Plus nodes may communicate through For most Modbus Plus nodes the paths are simply a managed resource and the first path available on a node is used when needed For the VMS environment slave data paths are addressed uniquely and their path number must be specified b
32. e of the connected Modbus Plus network devices and their addresses START type long access readonly mechanism by value Starting register in addressed PLC to beginning reading registers from Valid range for each file is 60000 to 69999 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS COUNT type word access readonly mechanism by value The number of packed registers to read from the addressed PLC If the number of registers exceeds what is able to read from a single Modbus Plus transfer multiple Modbus Plus transfers will be done FILE type word access readonly mechanism by value The extended memory of the PLC is broken up into 10000 registers each and the remaining amount for the last segment allowing registers in the range of 60000 to 69999 per file The file number ranges from one 1 to the available memory assigned in the PLC for extended memory in ten thousand register increments BUFFER type array access readonly mechanism by reference Caller array of registers to be written in the PLC STATUS type structure MBP_STATUS access write mechanism by reference Final status EFN type long word access readonly mechanism by value Event flag to set when I O is complete FLAG type long word access readonly mechanism by value If this FLAG is set to 1 then the data is not byte swapped before it is sent to the PLC 57 MODBUS Plus VMS INTERFACE LIBRARY APP
33. ecified not allocated or out of range Invalid starting address V O not complete on channel No channel open on path Specified path is not between one and the number allocated by MBP_OPEN_NET MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 13 MBP READ UNSOLICITED Read unsolicited mail from a Master Modbus Plus Node FORMAT MBP_READ_UNSOLICITED BUFFER CHANNEL EEN SIZE MBX_SIZE RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MBP_ error status codes ARGUMENTS MBPPEX type structure access readonly mechanism by reference Structure returned by MBP_OPEN_NET BUFFER type array access write mechanism by reference Caller array to receive the buffer from the PLC The message will contain at a minimum the the Modbus Plus header The remainder of the message is dependent on the MSTR block in the particular PLC that sent the message This buffer should be sized to MP K_UNSOLICITED_MSGSIZE unless the user used a different size in the MBP_REGISTER_UNSOLICITED_V call CHANNEL type longword access readonly mechanism by value Channel assigned to the unsolicited data mailbox EFN type longword access read mechanism by value Event flag to be used for I O synchronization MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS SIZE type longword access write mechanism by refe
34. ed Path specified not allocated or out of range Path is in use No channel open on path No channel open on path Invalid event flag specified V O not complete on channel VMS System Service Errors from QIO call MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 5 MBP GET SLAVE ID Modbus Plus node to return its id FORMAT MBP_GET_SLAVE_ID MBPPEX PATH ROUTE BUFFER EFN RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MBP_ error status codes ARGUMENTS MBPPEX type structure access readonly mechanism by reference Structure returned by MBP_OPEN_NET PATH type word access readonly mechanism by value Path that this I O is to be directed to Must be between one and the number allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference This is an array filled in by the caller that specifies the route path to the particular slave PLC The content of this array requires knowledge of the connected Modbus Plus network devices and their addresses This subroutine does not validate the route array MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS BUFFER type 9 byte array access write mechanism by reference Buffer to receive the Modbus Plus nodes slave id and status The format of the nine byte buffer is BYTE SLAVE_ID BYTE LED BYTE PAGEO
35. ed In this case the VAX emulates holding registers similar to a PLC with the first location addressed as register is 40001 This option is only supported with the MBP_REGISTER_UNSOLICITED routine call Since the PLC Programmable Logic Controller MSTR instruction specifies the actual path as part of its routing information the VMS host must either tell the PLC which path is to receive the message using technique described earlier or the VMS host must allocate known slave paths such that the PLC can be programmed to write to known slave data paths in the VMS host Defined slave paths are done by specifying an optional slave path vector array CTRL_PATHS in the MBP_OPEN_NET call 1 10 Non PLC Modbus Nodes It is possible to have Modbus Nodes which are not programmable Controllers Typical non Modbus nodes are either other VMS hosts or operator displays A typical application is where the VMS host provides supervisory information such as order information customer names product descriptions and other data not needed for the actual operation or control of the operations IPACT has used this feature with both UNICEL marketed by Modicon Factory Link by USData and InTouch by Wonderware Operator screens can be made that display information seamlessly without regard to the source of the information 1 11 _ _VAX and PLC Data Byte Order The Modicon PLCs and the VAX store data bytes in different order For data read or written to registers in
36. ed by user applications The structure MBPPEX is defined in the MBP_C TLB text library The MBPPEX is filled with the actual Program master paths that were allocated The process expanded region is created as a group global temporary section This allows other programs to map the region for analysis purposes while a user program is executing The name of the region is the process name prefixed with the device name e g MPA1_SCANNER Where SCANNER is the process name and MPA1 is the device name A process may connect to more than a single controller if desired using a unique MBPPEX structure for each controller All Program Master paths are allocated by the driver The program master paths allocated may or may not start with program master path one It is possible that some but not all of the master could not be allocated Therefore if this routine fails the caller should do its normal error recovery and then exit When a path is required for other library calls the path numbers are relative to those allocated by the driver The actual program master paths allocated are stored in the process expanded region returned in the MBPPEX structure Master Program paths have the form of 80 hex plus the path controller allocated path The path information may be viewed with Modbus Plus process monitor utility CONDITION VALUES RETURNED MBP_MAPFAIL MBP_WRNGNMBRPATHS Wrong number of paths Unable to create process region MBP_ASSIGNFAI
37. ended m EFN type long word mechanism by value peripheral Dim Awareness emory parity failure or Bad I O Traffic Cop Peripheral Port Stop Event flag for I O synchronization CONDITION MBP_NOTINITIALIZED VALUES RETURNED MBP_BADPATH MBP_PATHINUSE MBP_NOCHANNEL MBPPEX returned by MBP_OPEN_NET is corrupt or invalid The specified path is less than or greater than the number of master paths allocated by the MBP_OPEN_NET call A request to do a second read or write to the master path but the path is already active with a previous I O request There is not channel or path for the passed path argument The MBP_OPEN_NET most likely failed to allocate all of the desired paths Check status of the MBP_OPEN_NET call 23 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 6 MBP_HOST_WRITEABLE_REGION_V Define VMS regions for Master writes by Programmable Controllers by path VMS slave paths FORMAT MBP_HOST_WRITEABLE_REGION_V MBPPEX REGION_ARRAY RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access write mechanism by reference The structure to receive starting and ending address of the process specific data area used by the Modbus Plus interface subroutines see MBPPEX in MBPlus TLB REGION ARRAY type
38. ers start at 40500 CONTROL 0 and the data registers begin at 40600 DATA 0 The data area is 54 registers in length The MSTR instruction execution may be aborted by TIMEOUT ABORT which occurs when an MSTR instruction execution does not complete within 20 seconds TIMEOUT ABORT is reset 0 5 seconds after it occurs I I MSTR I MSTR MSTR CONTROL MSTR I DO MSTR DONE 0 ACTIVE T IFs 1 is I 01003 01007 40500 01004 T I MSTR MSTR I TIMEOUT DATA MSTR I ABORT 0 FAILURE I akee I 01010 40600 01005 ls T I MSTR I SUCCESS T 3 MSTR I 00054 01006 I x oo I MSTR I MSTR TIMEOUT I ACTIVE ABORT I a BEN x s i o I 01004 00020 01010 I I MSTR MSTR MSTR I ABORT MSTR ABORT ABORT I RESET DONE ACCUM RESET I 5 I T1 0 p i C I 01011 01007 40509 100005 01011 I K aa Eg ei aasi am hi I IMSTR I ABO DELAY I ACCUM I 6 T0 1 t I 40510 I E aan aa aa aeai op a i Sn 80 Appendix D Example VMSINSTALL MODBUS Plus VMS INTERFACE LIBRARY INSTALLATION D 1VMSINSTALL Example The following assumes all defaults when prompted The SQ85 should be installed in the microvax with the CSR address and VECTOR as entered below Users unfamilar with VMSINSTAL should consult the VMS System Manager documentation set A directory listing of the product directory is shown after the VMSINSTAL had completed IPACT Mi
39. et when I O is complete MTMO type long word access read mechanism by value Modbus Read Master Response timeout value in seconds Must be greater than two The DESCRIPTION This subroutine sets a single output register using the specified path The event flag is used for I O synchronization and if none is specified event flag zero is used The event flag will be set when all of the registers requested to be read have been read To satisfy the request this routine may do more than a single Modbus transfer This routine uses ASTs to process all I O completions and therefore must have adequate AST quota 16 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS CONDITION MBP_NOTINITIALIZED MBPPEX structure not initialized VALUES RETURNED MBP_IONOTCOMP T O not complete on channel MBP_NOCHANNEL No channel open on path MBP_PATHINUSE Path in use MBP_INVALIDEFN Invalid event flag specified MBP_BADSTARTADDR Invalid starting address MBP_BADPATH Path specified not allocated or out of range SYSTEM SERVICE From SYS QIO call 17 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 3 MBP GET DRIVER STATISTICS Return the driver statistics FORMAT MBP_GET_DRIVER_STATISTICS MBPPEX BUFFER RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MBP_ error status codes ARGUMENTS MEPPEX type structure access read
40. g with some actual PLC rungs that provide examples of communication logic The third chapter documents some utilities that were gathered from the driver distribution and written as tools for this software These tools will help you diagnose system faults and verify system operations 1 2 Interface Library The Modbus Plus VMS interface library provides a set of callable routines that reduces the effort required to communicate with devices on the Modbus Plus network This software is implemented as a shared vectored library that is linked into each application that desires to communicate with the devices on the network Because it is vectored upgrades to the interface library will not require the relinking or recompiling of application programs This software assumes the presence of the Modbus Plus device driver and the SQ85 or SA85 Modbus Plus gateway hardware The user should also reference the Modicon document Modicon DEC Host Based Devices User s Guide publication number GM HBDS 002 Rev B as an additional source of information 1 3 Shareable Image Entry Points The MBP interface calls and error status messages are all prefixed with MBP_ The MBP_SHARE sharable image contains the following entry points MBP_CLOSE_NET Close all channels and deallocate all paths to the Modbus Plus Network MBP_FORCE_SINGLE_COIL Force a single coil within a PLC on the Modbus Plus Network MBP_GET_DRIVER_STATISTICS Return current driver statistics
41. haracter zero terminated access readonly mechanism by reference Device name that slave path is allocated on MPAI MPA3 Note The Modbus Plus devices are created as two device pairs Specify the first device for a single SQ85 devices MPAO and MPAI are created specify MPA1 CTRL_SLAVE_PATH type longword access readonly mechanism by value SQ85 controller slave path number assigned to device by the target process to disable recognition of slave messages from MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS DESCRIPTION This subroutine allows the caller to stop the recognition of Modbus Plus slave messages of another process If mailboxes are being used the content of the mailboxes are not effected To use this entry the calling process must be in the same group as the target process such that the calling process may map the process expanded region of the target process The target VMS process is the process that has registered for unsolicited slave reads by calling one of MBP_REGISTER_ UNSOLICITED MPB_REGISTER_UNSOLICIED_V MBP_HOST_WRITEABLE_REGION_V This entry maps with write access the group global region named by concatenating the device less colon and the process name with an underscore separating them For example for a single SQ85 and a process named SCAN the region would be MPAI_SCAN This routine simply sets the disable bit in the region for the slave path requested The slave path
42. ice Drivers Manual for any Modbus errors Additional errors can be returned by the VAX VMS system service calls The MBPPEX structure has a secondary error status word that should also be consulted Any errors that cannot be returned to the caller such as the errors that occur during the response to a PLC master are logged to the system operator console via the SYS SNDOPR service B 1MBP Error Codes MBP_ASSIGNFAIL Unable to assign device The MBP_OPEN_NET was unable to assign the Modbus Plus communication device Most probable causes are that the driver is not loaded or the user is attaching to the wrong device Examine the mbp I_status in the MBPPEX structure MBP_BADPATH Path specified not allocated or out of range A call to one of the subroutines showed in path number that was not within range The path number must be between one and the number that was allocated by the MBP_OPEN_NET call MBP_BADSTARTADDR Invalid starting address User has passed an invalid starting register or coil number or has passed the value incorrectly 70 MODBUS Plus VMS INTERFACE LIBRARY ERROR CODES MBP_EXCEPTION Modbus exception response see byte count The Modbus Slave has responded with an exception The byte count returned to the caller contains the execption Consult the Modicon DEC Host Based Devices User s Guide for exception codes At the time of this writing the following were documented Exception Error Condition Code 01 Illegal
43. iding delay between triggers Additionally the repeat function may be deactivated if a preset number of successive failures occur I NODE PATH I VALID MSTR I TRIGGER START I 1 P H EJ I 00999 01001 T I I MANUAL I TRIGGER l I 2 F I 01000 I I MSTR STOP I MAX FAIL MSTR I EXCEEDED ACTIVE I I 34 Il INT Pe ee I 01012 01004 00015 I I MSTR I REPEAT I DLY ACCU I 4 4T 2 2 0 I 40531 I Keen 77 MODBUS Plus VMS INTERFACE LIBRARY EXAMPLES NETWORK 0007 Segment 01 Whenever the MSTR instruction is to be executed trigger occurs the success or failure result of the last execution must be cleared reset After the result of the last MSTR instruction execution is cleared the MSTR instruction execution is enabled by DO MSTR until it is completed DONE When an MSTR instruction execution terminates unsuccessfully a counter is incremented when termination is successful the counter is reset If the counter accumulator value reaches the preset value 999 the MSTR instruction is disabled via STOP MAX FAIL EXCEEDED I I MSTR MSTR MSTR I START DONE GOOD RESET I 14 JPI H J I H I 01001 01008 01002 I I I MSTR I DONE BAD I 2 Jie ul I 01009 I I I MSTR MSTR MSTR MSTR I DONE GOOD DONE BAD DONE DO MSTR
44. igned for unsolicited messages Invalid argument Attempt to allocate second read on same slave path Slave read failure 25 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 7 MBP_OPEN_NET Enable Modbus Communications FORMAT MBP_OPEN_NET MBPPEX DEVICE MASTER_PATHS SLAVE_PATHS CTRL_PATHS RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access write mechanism by reference The structure to receive the starting and ending address of the process specific data area used by the Modbus Plus interface subroutines see MBPPEX in MBPlus TLB DEVICE type character access read only mechanism by descriptor This specifies the name of the Modbus Plus interface MPA1 MPB1 MPC1 or MPD1 MASTER_PATHS type word access read only mechanism by value This specifies the number of master paths the caller desires to allocate for its use Depending on the controller there are a certain number of paths available to be used See Modbus Plus documentation for a description of PATH If the entire number of paths specified cannot be allocated then none are allocated MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS SLAVE_PATHS type word access read only mechanism by value This specifies the number of slave
45. ixteen bit registers the bytes may need to be swapped to convert them to the VAX sixteen bit word format If the data contains ASCII data or is a group of discretes packed 8 to a byte then do not swap the bytes If the optional parameter MBX_SIZE is not specified then the default size MP K_UNSOLICITED_MSGSIZE is used Since this service uses the mailbox driver a mailbox created by the MBP_REGISTER_UNSOLICITED_V with a mailbox smaller than MP K_UNSOLICITED_MSGSIZE will result in a mailbox too small error If the mailbox is larger than MP K_UNSOLICIED_MSGSIZE a data overun error will occur The MBP_REGISTER_ UNSOLICITED call creates a single mailbox of the default size 43 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS MBP_NOTINITIALIZED MBPPEX returned by MBP_OPEN_NET is corrupt or CONDITION invalid VALUES RETURNED MBP_BADPATH The specified path is less than or greater than the number of master paths allocated by the MBP_OPEN_NET call MBP_PATHINUSE A request to do a second read or write to the master path but the path is already active with a previous I O request MBP_NOCHANNEL There is no channel or path assigned to the specified path The MBP_OPEN_NET most likely failed to allocate all of the desired paths Check status of the MBP_OPEN_NET call SYSTEM Result of VMS SYS QIO call SS _MBTOOSML The user has requested a buffer larger than the size of mailbox The user buffer should not be larger than MP
46. lation and remove the old version and unload the driver if it is loaded Continue with installation Y y How many SQ85 devices 1 Enter CSR for controller in OCTAL 0 766770 766000 Enter VECTOR for controller in OCTAL 0 310 320 SQ85 0 CSR 766000 VECTOR 320 Are these correct Y y MBP_I_COFFEEBREAK answer section complete MBP_I_LINKING linking shared image MBP_SHARE MBP_I_LINKING linking SQ85 device driver MPDRIVER MBP_I_COMMAND Building startup command file MBP_STARTUP COM MBP_I_ DIRECTORY Creating IPACT DUAO0 SYS0 S YSCOMMON MBP012 VMSINSTAL I SYSDIR This product creates system disk directory IPACT DUAO SYS0 S YSCOMMON MBP012 VMSINSTAL I SYSDIR This product creates system disk directory IPACT DUAO0 SYS0 S YSCOMMON MBP012 EXAMPLES MBP_I_MOVING Marking files to move MBP_I_COMPLETE KITINSTAL COM complete This kit is supplied with an IVP that is part of the VMSINSTAL kit If you choose to execute the IVP then the driver and shared image will be installed If you have an old version on your system you should not run the IVP Additonally if you suspect that the SQ85 may not be installed correctly or you have never tried it before you should not execute the IVP as a system crash may result You may at a convient time when you can tolerate a system crash execute the MBP_STARTUP COM command file that was created and then run the utilties CK_PROG and then NDU see documentation The
47. library or an object library To link to the object library the linker commands are LINK EXEstest exe SYS INPUT OPTIONS test mbplus_ mbp olb include mbpshare_msg mpdriver_msg mbplus_ mbp olb lib sys library vaxcrtl lib To link to the shared library the following linker commmands should be used LINK EXEstest exe SYS INPUT OPTIONS test mbplus_ mbp_share share mbplus_ mbp olb include mbpshare_msg mpdriver_msg mbplus_ mbp olb lib sys library vaxcrtl lib The logical MBPLUS_ is initialized by the command file created by VMSINSTAL kit MBP_STARTUP COM The object library method is provided to allow the programmer to link to an object library or a debug object library The debug library allows the programmer to isolate faults that might be occurring within the shared library and assist in reporting bugs to the developers These two libraries are MBP OLB and MBP_DBG OLB 1 3 4 Example Programs The subdirectory MBPLUS_ Examples contains example programs that may be used to test the network or as a basis to code user applications A command file MENU COM provides easy test of these routines The user is cautioned that these example programs will write to the target Modbus Plus node causing undesirable results if the target node is controlling a process 1 3 4 1 Process Privileges Users of the Modbus Plus device driver must have the following privileges SYSNAME To allocate a permanent mailbox for data messages f
48. n one and the number allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference The is an array filled in by the caller that specifies the route path to the particular PLC The content of this array requires knowledge of the connected Modbus Plus network devices and their addresses START type long access readonly mechanism by value Starting register in addressed PLC to beginning writing user registers to The START register is used to determine if a FORCE of the coils or a PRESET of the registers will be done Only coils 00001 to 09999 and holding registers 40001 to 49999 may be written to MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS COUNT type word access readonly mechanism by value The number of packed registers to write to the addressed PLC If the number of registers exceeds what is able to written in a single Modbus Plus transfer multiple Modbus Plus transfers will be done BUFFER type array access read mechanism by reference Caller array to acquire the registers for the PLC STATUS type structure MBP_STATUS access write mechanism by reference Final status EFN type long word access readonly mechanism by value Event flag to set when I O is complete FLAG type long word access readonly mechanism by value If FLAG is set to 1 then the data is not byte swapped before it is written to the PLC MTMO
49. ndicating a routing error response The routing failure code will be set to indicate 10 Slave rejected command If the mailbox is to be created as a permanent mailbox the caller must have SYSNAM privilege The reading process can be either the current process or any other process in the system The MBP_READ_ UNSOLICITED entry may be called to actually read the message from the mailbox The actual content of the letter contained in the mailbox is documented in the Modicon DEC Host Based Devices User s Guide under the IO _READ_SC command The complete message including the Modbus Plus header is placed into the mailbox The actual format of the data portion of the message has to be defined with the programmer of the PLC sending Master PLCs or other Modbus Plus Master nodes on the Modbus Plus network can only read and write the host holding registers 40001 to 49999 This entry also supports the ability of the calling process to allow master reads from Master PLCs or other Modbus Plus Masters to request HOST holding registers If the calling process 46 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS desires to support this functionality then the address of a word array representing the host s holding registers must be passed Only the slave paths allocated by this process will be able to respond with host register values The host holding registers can be a global section that is mapped by the calling process
50. nique mailbox per path FORMAT MBP_REGISTER_UNSOLICITED_V MBPPEX MBX_ARRAY RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access write mechanism by reference The structure to receive starting and ending address of the process specific data area used by the Modbus Plus interface subroutines see MBPPEX in MBPlus TLB MBX_ARRAY type structure array access read write mechanism by reference This structure should be dimensioned by eight number of modbus slave paths An entry should be filled in for slave path allocated in the MBP_OPEN_NET call The content of each array element is Mailbox name type character access readonly This is a 1 to 32 character zero terminated name of the mailbox If the caller does not have system name privilege the name is ignored by the create mailbox system service Permanent_flag type byte access readonly If non zero then the mailbox should be set as a permanent mailbox MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS DESCRIPTION Letter count type word access readonly The number of messages that the mailbox should be created to contain Letter size type word access readonly This contains the size of each message in the mailbox default is MP K_UNSOLICITED_MSGSI
51. ntained by all members of the Modbus Plus network CONDITION MBP_NOTINITIALIZED MBPPEX returned by MBP_OPEN_NET is corrupt or VALUES RETURNED invalid MBP_BADPATH The specified path is less than or greater than the number of master paths allocated by the MBP_OPEN_NET call MBP_INVALIDEFN Invalid event flag specified MBP_PATHINUSE A request to do a second read or write to the master path but the path is already active with a previous I O request MBP_BADPATH MBP_NOCHANNEL MBP_IONOTCOMP MBP_NOCHANNEL Path specified not allocated or out of range No channel open on path V O not complete on channel There is no channel or path assigned to the specified path The MBP_OPEN_NET most likely failed to allocate all of the desired paths Check status of the MBP_OPEN_NET call MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 12 MBP READ REGISTERS Read registers from a Modbus Plus slave node FORMAT MBP_READ_REGISTERS W MBPPEX PATH ROUTE START COUNT BUFFER STATUS EFN FLAG MTMO RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access readonly mechanism by reference The structure that was returned by the MBP_OPEN_NET call PATH type word access readonly mechanism by value Path that this I O i
52. only mechanism by reference The structure that was returned by the MBP_OPEN_NET call BUFFER type 316 Byte Array access Write mechanism By reference Buffer to receive the driver status and statistics See DEC Host Based Devices User s Guide for a description of the returned record DESCRIPTION This subroutine requests the local device driver to return the driver statistics to the user supplied buffer The layout of the 316 byte buffer is described in the Modicon DEC Host Based Devices User s Guide see IO _GET_SS Get Driver Status and Statistics This routine completes synchronously This call is done to the first channel that was allocated by the MBP_OPEN_NET service This function does not require a path It always uses the first master path allocated CONDITION MBP_NOTINITIALIZED MBPPEX returned by MBP_OPEN_NET is corrupt or VALUES invalid RETURNED MBP_NOCHANNEL No channel open on path SYSTEM SERVICE VMS System Service Errors Modbus Errors See Modicon DEC Host Based Devices User s Guide and the appendix 18 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 4 MBP_GET_NETWORK_ STATISTICS Get Modbus Plus counters and statistics FORMAT MBP_GET_NETWORK _ STATISTICS MBPPEX PATH ROUTE BUFFER CLEAR STATUS EFN RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MBP_ error status codes ARGUMENTS MBPPEX type str
53. ot writable The specified path already has an I O active Path specified not allocated or out of range No channel open on path Invalid starting address V O not complete on channel MBPPEX structure not initialized Invalid event flag specified Specified path is not between one and the number allocated by MBP_OPEN_NET 58 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 19 MBP _ WRITE GLOBAL DATA Write Modbus Plus 64 bytes of global data FORMAT MBP_WRITE_GLOBAL_DATA MBPPEX PATH BUFFER EFN STATUS RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MBP_ error status codes ARGUMENTS MBPPEX type structure access readonly mechanism by reference Structure returned by MBP_OPEN_NET PATH type word access readonly mechanism by value Path to use for the I O BUFFER type array access read mechanism by reference Contains the 64 byte buffer to be written to this controller s global data area EFN type long word access readonly mechanism by value T O event flag for synchronization STATUS type structure MBP_STATUS access write mechanims by reference V O completion status MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS DESCRIPTION This subroutine will write the 64 bytes of global data This routine operates synchronously as the data is local in the computer s con
54. paths to allocate for the caller for the purpose of receiving unsolicited messages See MBP_REGISTER_UNSOLICITED subroutine entry CTRL_PATHS type word array access read only mechanism by reference Optional controller slave path numbers for each slave path allocated If not specified the driver will be asked to allocate the next free controller slave path number If the slave path is not available e g in use by another application the driver will return a path in use error code DESCRIPTION This subroutine open channels and allocate paths to be used for communicating with the Modbus Plus network This subroutine expands the callers PO space to allocate working storage for future calls to the Modbus Plus network The structure MBPPEX that is returned to the user must be passed on all subsequent calls to the other Modbus Plus software interface routines This is normally the first call by the user application software The structure MBPPEX is defined in the MBP_C TLB text library The MBPPEX is filled with the actual slave paths and master paths that were allocated The process expanded region is created as a group global temporary section This allows other programs to map the region for analysis purposes while a user program is executing The name of the region is the process name prefixed with the device name e g MPA1_SCANNER Where SCANNER is the process name and MPA1 is the device name A process may connect to more than
55. product directory also contains the files MBPLUS COM and MBPLUS RNO which will allow you to create additional copies of the documentation Execute IVP Y n Your installation is now complete After the files are moved we will test your installation if you requested it 83 MODBUS Plus VMS INTERFACE LIBRARY INSTALLATION VMSINSTAL I MOVEFILES Files will now be moved to their target directories Installation of MBP V1 2 completed at 08 18 Enter the products to be processed from the next distribution volume set Products VMSINSTAL procedure done at 08 18 Directory SYS COMMON MBP012 CK_PROG EXE 1 DSPMBP EXE 1 EXAMPLES DIR 1 MBP OLB 1 MBPLUS COM 1 MBPLUS RNO 1 MBP_C TLB 1 MBP_DBG OLB 1 MBP_FOR TLB 1 MBP_SHARE EXE 1 MBP_STARTUP COM 1 MPDRIVER EXE 1 NDU EXE 1 Total of 13 files 84 MODBUS Plus VMS INTERFACE LIBRARY INSTALLATION Directory SYS COMMON MBP012 EXAMPLES BITSTR FOR 1 BUILD_ALL COM 1 DSPMBP COM 1 DSPMBP FOR 1 EXAMPLE C 1 FORCE_SINGLE_COIL_EX COM 1 FORCE_SINGLE_COIL_EX EXE 1 FORCE_SINGLE_COIL_EX FOR 1 GET_DRIVER_STATISTICS_EX COM 1 GET_DRIVER_STATISTICS_EX EXE 1 GET_DRIVER_STATISTICS_EX FOR 1 GET_NETWORK_STATISTICS_EX COM 1 GET_NETWORK_STATISTICS_EX EXE 1 GET_NETWORK_STATISTICS_EX FOR 1 MENU COM 1 PRESET_SINGLE_REGISTER_EX COM 1 PRESET_SINGLE_REGISTER_EX EXE 1 PRESET_SINGLE_REGISTER_EX FOR 1 READ_WRITE_GLOBAL_DATA_EX COM 1 READ_WRITE_GLOBAL_DATA_EX EXE 1 READ_WRITE_GLOBAL_DATA_EX F
56. rence Return size of the message that was read in bytes Includes complete header and data MBX_SIZE type longword access write mechanism by value Optional parameter that specifies the size of the unsolicited mailbox DESCRIPTION This routine allows the caller to read messages from the unsolicited mailbox set up by either the caller or some other caller This routine will read the message as placed by the process that has registered for the Modbus slave messages on a particular path see MBP_REGISTER_UNSOLICITED This routine is passed the channel that is assigned to the unsolicited mailbox If the process reading the mailbox is the same process that registered for the unsolicited messages then it is the channel returned by MBP_REGISTER_UNSOLICITED otherwise it is the channel number assigned to a permanent mailbox created by the process that called MBP_REGISTER UNSOLICITED and assigned by calling process using the VMS system service SYS ASSIGN If there is no message available this service waits This routine basically does the QIOW service to read the mailbox If the user desires an asynchronous version the user may do a normal QIO consult the VMS mailbox driver for further details The message contains the Modbus header the C header file mbp_bufdef h contains the definition of the Modbus Plus header and the actual data message from the PLC master No byte swapping is done on the data If the data is true s
57. rom the PLCs PHY_IO Physical I O privilege to access the Modbus Plus device driver MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW 1 3 4 2 Process Quotas This software does not require any abnormal quotas to function However the following are provided for fault analysis and determining if normal quotas are not present AST Quota For each possible I O an AST entry is required An I O is present for each slave and master path that the caller allocates PGFLQUOTA Page file quota The process expanded region is allocated from the system page file This is typically three pages plus one page for each path that is allocated WSQUOTA See PGFLQUOTA 1 4 Modbus Network This software differs in the handling of the Modbus Plus Network addressing as compared to the MODCOM II software library this MODCOM III library is a predecessor of this software and the calls available in the MODCOM III library have been replaced by these services This software assumes that the user maintains his own mechanism of cross referencing a particular PLC and the route path to a particular PLC The route array is a five byte array that specifies the navigation to the target PLC The last non zero byte in the array must be the Modbus Plus node address For further explanation of the route array consult the Modicon DEC Host Based Devices User s Guide Possible methods of maintaining the routing database are program data statements include definition files macro
58. s are the controller slave path numberes as allocated by the driver and referenced by the SQ85 This is the second parameter in aPLC MSTR route information CONDITION MBP_NOSLAVE No slave paths were allocated VALUES RETURNED MBP_MBXFAIL Unable to create mailbox see secondary status will contain the VMS system service code MBP_NOSUCHPATH The desired slave path was not allocated to the target process MBP_NOSLAVEMATCH Controller slave path was assigned by process 55 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 18 MBP WRITE EXTENDED Write extended memory files in a Modbus Plus slave node FORMAT MBP_WRITE_EXTENDED W MBPPEX PATH ROUTE START COUNT FILE BUFFER STATUS EFN FLAGLMTMO RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access readonly mechanism by reference The structure that was returned by the MBP_OPEN_NET call PATH type word access readonly mechanism by value Path that this I O is to be directed to The path must be between one and the number allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference This is an array filled in by the caller that specifies the route path to the particular PLC The content of this array requires knowledg
59. s is invalid not readable or not writable MBP_PATHINUSE The specified path already has an I O active MBP_BADSTARTADDR Invalid starting address MPB_INVLPATH Specified path is not between one and the number allocated by MBP_OPEN_NET 63 Chapter 3 Utilities MODBUS Plus VMS INTERFACE LIBRARY UTILITIES 3 1 Introduction The following utilities will help the VAX programmer and system manager tune debug and provide help in fault analysis Some of the utilties are provided by with the device driver software and some are provided with this software 3 2 Network Diagnostic Utility The NDU utility provides a general purpose program that allows the VAX programmer and system manager to diagnose Modbus Plus health and operation It is further documented in the Modicon DEC Host Based Devices User s Guide 3 3 Monitor Modbus Plus Process Any program that is using the Modbus Plus application library also exposes a part of its process as a group global section The group global section contains statistics and status relative to the execution of the communication routines and the master and slave paths This process displays information from this region for any process that is currently running to the users terminal The process to be examined must be in the same group as the user as the section is a Group global section and not a System global section DSPMBP is invoked with the following DCL command The global section name mus
60. s placed into the caller s buffer MTMO type long word access read mechanism by value Modbus Read Master Response timeout value in seconds Must be greater than two DESCRIPTION This subroutine reads the registers from the specified path The event flag is used for V O synchronization and if none is specified event flag zero is used The event flag will be set when all of the registers requested to be read have been read To satisfy the request this routine may do more than a single Modbus transfer This routine 40 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS uses ASTs to process all I O completions and therefore must have adequate AST quota The size of the buffer should be sized for either 8 bits per byte for discretes Oxxxx 1xxxx or two bytes per register 3xxxxx 4xxxxx All reads of registers are byte swapped to confrom to standard VMS sixteen bit word formats unless the FLAG argument is set to one This subroutine is available in the synchronous and asynchronous versions CONDITION MBP_MBPPEXINVLD VALUES RETURNED MBP_INVALIDARG MBP_PATHINUSE MBP_INVALIDEFN MBP_NOTINITIALIZED MBP_BADPATH MBP_BADSTARTADDR MBP_IONOTCOMP MBP_NOCHANNEL MPB_INVLPATH 41 MBPPEX structure is invalid One of the call arguments is invalid not readable or not writable The specified path already has an I O active Invalid event flag specified MBPPEX structure not initialized Path sp
61. s to be directed to The path must be between one and the number allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference This is an array filled in by the caller that specifies the route path to the particular PLC The content of this array requires knowledge of the connected Modbus Plus network devices and their addresses START type long access readonly mechanism by value Starting register in addressed PLC to beginning writing user registers to The ten thousand position of START is used to determine if coil status Oxxxx input status 1xxxx holding registers 4xxxx or input registers 3xxxx are to be read 39 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS COUNT type word access readonly mechanism by value The number of packed registers to read from the addressed PLC If the number of registers exceeds what is able to read from a single Modbus Plus transfer multiple Modbus Plus transfers will be done BUFFER type array access write mechanism by reference Caller array to receive the registers from the PLC STATUS type structure MBP_STATUS access write mechanism by reference Final status EFN type long word access readonly mechanism by value Event flag to set when I O is complete FLAG type long word access readonly mechanism by value If FLAG is set to 1 then the data is not byte swapped when it i
62. ss activation but not over system bootstraps MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS MBX_CHANNEL type long word access write mechanism by reference The actual channel number assigned to the mailbox is returned to the caller This channel should be used for the user s or other user s to dequeue messages from using the standard VMS QIO system service calls HOLDING_REGISTERS type word array access read only mechanism by reference Address of holding registers array Used to service read holding registers from another Master on the Modbus Plus network NUMBER_HOLDING_REGISTERS type longword access read only mechanism by value Number holding registers in holding register array Each holding register is two bytes long DESCRIPTION This subroutine allows the caller to set up a mailbox to receive slave messages from devices on the Modbus Plus network The caller passes the name of a mailbox and if the mailbox should be permanent or not If the mailbox is permanent the MSG_CNT will not be used if the mailbox already exists on a subsequent activation of the process The caller must have already allocated slave paths via the MPB_OPEN_NET call This subroutine will post another read on each of the slave paths and write the messages to the mailbox when the messages are received In the event the mailbox becomes full the software will respond to the remote device with the Modbus Plus slave response i
63. st develop locking techniques that will prevent one writer from overwriting another s output This should be considered if the MBP_WRITE_REGISTERS calls are used by more than one process on one or more nodes If host holding register are to be used the synchronization of the reads and writes to the host holding registers are the responsibility of the user VMS locking and synchronization techniques can be used for this purpose The process that allocates the slave paths provides all access for remote Modbus Plus master nodes via AST routines within the Modbus Plus Interface Library Controlling the AST recognition of this process will control access to the host holding registers by the Modbus Plus master nodes Note See VMS documentation on process AST states lock manager event flags and other methods of process synchronization To disable AST recognition see the SYS SETAST VMS system service Additionally a process can have only one AST active which in itself can be used for synchronization If changes to the region only occur at AST level a consistent view of the region can be provided for remote Modbus Plus nodes 1 14 _ Process Expanded Region Each process that uses the Modbus Plus Application Interface library has a group global section created when the MBP_OPEN_NET is called This region is used by the Modbus Plus Process Monitor utility see utilities chapter It also provides the ability for another process to enable or disable the re
64. ster This subroutine does not support the ability of the remote PLCs to read from the VAX holding registers CONDITION MBP_NOSLAVE No slave paths were allocated VALUES RETURNED MBP_NOTINITIALIZED MBPPEX structure not initialized 50 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS MBP_MBXFAIL MBP_NOSLAVE MBP_SLVREADFAIL MBP_SLVBUSY MBP_MBXCREFAIL MBP_MBXSIZE Unable to create mailbox see secondary status will contain the VMS system service code Caller did not allocate any slave paths Slave read failure Attempt to allocate second read on same slave path VMS SYS CREMBX failed Examine MBP L_STATUS in the MBPPEX structure for the System Service status Size of the mailbox is too small Must be larger than modbus plus message header 51 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 16 MBP RESUME UNSOLICITED Restore the recognition of Modbus Plus slave messages of a Modbus Plus connected VMS process FORMAT MBP_RESUME_UNSOLICITED MBPPEX PROCESS_NAME DEVICE CTRL_SLAVE_PATH RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access read mechanism by reference The structure to receive starting and ending address of the process specific data area used by the Modbus Plus interface subrou
65. sting IO WRITE_SR status XL SL bytes to XB This error is logged on the system console It is generated when the VAX host attempts to a Slave Write to the PLC master Examine the I O status displayed and consult the Modicon DEC host Based Devices User s Guide MBP_WRNGNMBRPATHS Wrong number of paths The caller specified an incorrect number of paths 73 MODBUS Plus VMS INTERFACE LIBRARY ERROR CODES B 2 Routing Errors The following errors are a result of a Modbus Plus routing error The routing failure code was translated from the code listed in Modicon DEC Host Based Device User s Guide to one of the following symbolic codes Additional information in the buffer at time of this writing is Byte Contents Number 4 Contains MAC function code Hex 13 8 Routing Failure index 15 Device type of the failed node see Documentation 16 Failure code translated to one of the following MBP error codes MBP_BADDESTADDR Bad destination address MBP_BRIDGEBUSY Bridge Plus Paths busy MBP_EXCEPTIONRESPONSE Exception response received MBP_FORGOTTEN Forgotten transaction MBP_INVALIDPATH Invalid path MBP_INVALIDROUTE Invalid route MBP_NODEOFFLINE Node is off line MBP_NORRESPONSE No Response received from Modbus node MBP_PROGACCESSDENIED Program access denied MBP_SLAVEDOWN Slave device is down MBP_SLAVEREJECT Slave rejected message MBP_UNKRTRERR Unknown routing error MBP_UNSUPPORTED Unsupported MAC function 74 Appendi
66. t register was 40001 Only the read and write of holding registers is supported MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS The caller must determine if the slave paths allocated by the current process are to be written to a global region or it the data should be sent to a mailbox A process can only support one method for responding to the Master Writes If both functionality is desired a second process must be present to service the other method See the MBP_REGISTER_ UNSOLICITED call as well The byte order and synchronization of data within the Host Holding Register regions are the responsibility of the user The VMS process that calls MBP_HOST_WRITEABLE_REGION supports the actual data transfer between the Modbus Plus device driver at AST level Therefore disabling the AST recognition of this VMS process while the region is being modified will guarantee atomic and consistent data for Modbus Plus Master nodes reading data from the Host s holding registers The method used must ensure that the process will be able to respond to the Master Modbus Plus node prior to the Master node timing out because no slave data response from the VMS host was received CONDITION VALUES RETURNED MBP_NOSLAVE MBP_MBXFAIL MBP_SLVASSIGNED MBP_INVALIDARG MBP_SLVBUSY MBP_SLVREADFAIL No slave paths were allocated Unable to create mailbox see secondary status will contain the VMS system service code Slave path already ass
67. t be specified with the NAME switch This must be defined as a foreign DCL command DSPMBP MBPLUS_ DSPMBP EXE DSPMBP NAME global_section_name FULL CLEAR NAME The user must specify the name of the global section that is to be displayed The global section name consists of the device name being used to communicate with the Modbus Plus network ie MPAI MPB1 plus the process name The global region is created when the indicated process called MBP_OPEN_NET If the desired process was SCANNER and it specified the SQ85 or SA85 device MPA1 then the global section name would be MPA1_SCANNER FULL Forces the entire contents of the global section to be displayed The default is to display only selected fields CLEAR Forces specific counters and timers to be reset 65 MODBUS Plus VMS INTERFACE LIBRARY UTILITIES The following are example displays captured from an operational system DSPMBP NAME MPAI_MONITOR_SCANNER Paths MBX Last Last R W Start End Address MST SLV EFN Chan Read Write Status Process Name 001CD200 001CD9FF 01 01 000 4 11 29 19 4 11 29 19 00000000 MONITOR_SCANNER MASTER PATH 1 SLAVE PATH 1 Modbus I O status Modbus I O status Condition code t 1 Condition code 1 Transfer 20 Transfer 2 0 Crash code J 0 Crash code 2 0 Path number 2 Path number 66 Last read write 0 020000 0 040000 Last read 0 000000 Read Write counter 10390
68. te swapped before written to the PLC holding register STATUS type structure MBP_STATUS access write mechanism by reference Final status EFN type long word access read mechanism by value Event flag to set when I O is complete MTMO type long word access read mechanism by value Modbus Read Master Response timeout value in seconds Must be greater than two DESCRIPTION This subroutine sets a single output register using the specified path The event flag is used for I O synchronization and if none is specified event flag zero is used The event flag will be set when the register requested to be set has been set This routine uses ASTs to process all I O completions and therefore must have adequate AST quota This routine will byte swap the user register before sending it to the holding register within the PLC addressed by the route array Both the synchronous and asynchronous versions are available 32 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS CONDITION MBP_NOTINITIALIZED MBPPEX returned by MBP_OPEN_NET is corrupt or VALUES invalid RETURNED MBP_BADPATH The specified path is less than or greater than the number of master paths allocated by the MBP_OPEN_NET call MBP_PATHINUSE A request to do a second read or write to the master path but the path is already active with a previous I O request MBP_NOCHANNEL There is no channel or path assigned to the specified path The MBP_OPEN
69. the PLC this software will automatically swap the data for the register data For example if a holding register in the PLC contained a simple counter and it currently read 2011 hex the same sixteen bit data word read by the VAX would have been 1120 hex if this software did not swap the data This byte swapping is only performed on register data MBP_READ_REGISTERS MBP_WRITE_REGISTERS MBP_WRITE_EXTENDED MBP_READ_ EXTENDED The unsolicited data from the PLC is placed into the mailbox as it is received from the PLC on the Modbus Plus Network This software is unable to determine if the data should be byte swapped when it is received from the PLC Therefore the responsibility for this determination must be resolved by the programmer of the PLC and the VAX programmer 11 MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW 1 12 Application Status Returns All of the calls to the Application Library return status to the caller as the value of the function call similar to normal VMS standards If the a status block is returned it s format is as follows in bytes 3 1 1 5 0 MBP_ Error Code O Error Specific Transfer size 4 The following definition is contained in the MBP_C and MBP_FOR text libraries as MBP_STATUS 1 13 _ _ Contention and Synchronization Issues This software assumes that the caller maintains all control and access to the PLC registers If there are multiple writers then these writers mu
70. tines see MBPPEX in MBPlus TLB PROCESS_NAME type character zero terminated access readonly mechanism by reference Process name of the target process DEVICE type character zero terminated access readonly mechanism by reference Device name that slave path is allocated on MPA1 MPB1 Note The Modbus Plus devices are created as two device pairs Specify the first device for a single SQ85 devices MPAO and MPAI are created specify MPA1 CTRL_SLAVE_PATH type longword access readonly mechanism by value SQ85 controller slave path number assigned to device by the target process to enable recognition of slave messages from MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS DESCRIPTION This subroutine allows the caller to restore the recognition of Modbus Plus slave messages of another process To use this entry the calling process must be in the same group as the target process such that it may map the process expanded region of the target VMS process The target VMS process is the process that has registered for unsolicited slave reads by calling one of MBP_REGISTER_ UNSOLICITED MPB_REGISTER_UNSOLICIED_V MBP_HOST_WRITEABLE_REGION_V This entry maps with write access the group global region named by concatenating the device less colon and the process name with an underscore separating them For example for a single SQ85 and a process named SCAN the region would be MPAI_SCAN This
71. to develop redundant VAX hosts without changing logic in the PLC o The ability for the VAX programmer to partition and even distribute functionality to multiple programs running on either the same or different VAXs 1 6 1 PLC MSTR Example Assuming that there are eight PLCs Modbus Plus addresses 1 to 8 and two VAXs Modbus Plus addresses 20 and 21 Each of the PLCs has two MSTR blocks The first MSTR block is responsible for sending a transaction containing completed counts and statistics about a product just made to the Production Management VAX The second MSTR block is responsible for uploading significant event and current process history to a process Process History VAX In the event that either of the VAX are unavailable the other VAX assumes the functions of the failed VAX In each PLC the following holding registers are defined 1 MSTR block one route byte 1 node MSTR block one route byte 2 data path MSTR block two route byte 1 node MSTR block two route byte 2 data path BD In normal operation the Production Management VAX writes its Modbus Plus address in the 40001 holding register for all of the PLCs The Production Management VAX allocates five paths and writes the returned path numbers from the MBP_OPEN_NET call See MBPPEX structure in the 40002 holding registers of the eight PLCs assigning two PLCs per data path In a similar fashion the Process History VAX would write its node address into the 40003 of th
72. troller Only the local SQ85 s global data can be written to No byte swapping of data is performed CONDITION MBP_NOTINITIALIZED MBPPEX returned by MBP_OPEN_NET is corrupt or VALUES invalid RETURNED MBP_BADPATH The specified path is less than or greater than the number of master paths allocated by the MBP_OPEN_NET call MBP_PATHINUSE A request to do a second read or write to the master path but the path is already active with a previous I O request MBP_NOCHANNEL No channel open on path MBP_IONOTCOMP T O not complete on channel MBP_INVALIDEFN Invalid event flag specified MBP_NOCHANNEL There is no channel or path assigned to the specified path The MBP_OPEN_NET most likely failed to allocate all of the desired paths Check status of the MBP_OPEN_NET call 60 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS 2 20 MBP WRITE REGISTERS Write registers to a slave Modbus Plus node FORMAT MBP_WRITE_REGISTERS W MBPPEX PATH ROUTE START COUNT BUFFER STATUS EFN FLAG MTMO RETURNS VMS usage COND_VALUE type longword mechanism by value Longword status as defined by either a system service call or the MPB_xxxx status codes see error codes listed below ARGUMENTS MBPPEX type structure access readonly mechanism by reference The structure that was returned by the MBP_OPEN_NET call PATH type word access readonly mechanism by value Path that this I O is directed to The path must be betwee
73. type long word access read mechanism by value Modbus Read Master Response timeout value in seconds Must be greater than two DESCRIPTION This subroutine writes the user buffer to the registers within the PLC addressed by the specified route array The event flag is used for I O synchronization and if none is specified event flag zero is used The event flag will be set when all of the registers specified have been written To satisfy the request this routine may do more than a single Modbus 62 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS transfer may This routine uses ASTs to process all I O completions and therefore must have adequate AST quota The START register number is used to determine which type of output is being performed The source buffer should be sized for two bytes per holding register or eight registers per byte for coils For register transfers the VAX sixteen bit word is byte swapped to match the format of the PLC sixteen bit registers unless the FLAG argument is set to one Both the synchronous and asynchronous version is available CONDITION MBP_MBPPEXINVLD MBPPEX structure is invalid VALUES RETURNED MBP_INVALIDEFN Invalid event flag specified MBP_NOCHANNEL No channel open on path MBP_IONOTCOMP T O not complete on channel MBP_BADPATH Path specified not allocated or out of range MBP_NOTINITIALIZED MBPPEX structure not initialized MBP_INVALIDARG One of the call argument
74. ucture access readonly mechanism by reference Structure returned by MBP_OPEN_NET PATH type word access readonly mechanism by value Path that this I O is to be directed to Must be between one and the number allocated by the MBP_OPEN_NET call ROUTE type five byte array access readonly mechanism by reference This is an array filled in by the caller that specifies the route path to the particular PLC The content of this array requires knowledge of the connected Modbus Plus network devices and their addresses This subroutine does not validate the route array BUFFER type 110 byte array access write mechanism by reference Buffer to receive the Modbus Plus status and statistics from the SQ85 MODBUS Plus VMS INTERFACE LIBRARY APPLICATION LIBRARY CALLS CLEAR type word access readonly mechanism by value If true 1 read and clear the statistics else only read STATUS type structure MBP_STATUS access write mechanism by reference Final status EFN type long word mechanism by value Event flag for I O synchronization DESCRIPTION This routine asks the SQ85 to return its Modbus Plus counters and statistics By setting the Clear flag to true the counters are optionally cleared This entry executes synchronously CONDITION MBP_NOTINITIALIZED ee MBP_BADPATH MBP_PATHINUSE MBP_NOCHANNEL MBP_ INVALIDEFN MPB_IONOTCOMP SYSTEM SERVICE MBPPEX structure not initializ
75. ve and the PLC or another Modbus Plus node is the master The PLC uses the MSTR instruction to read or write to or from the VAX The PLC writes are directed to one of the following only one of the following methods is supported at the same time by the same VMS process 1 A single VAX mailbox for all paths with optional readonly slave region MBP_REGISTER_UNSOLICITED 2 A VAX mailbox by path MBP_REGISTER_UNSOLICITED_V 3 Anarray or region by path for read or write access MBP_MBP_HOST_WRITEABLE_REGION_V Each of these three options are shown in the following diagrams MBX_NAME Readable Host Holding Registers Modbus Plus oS MP Driver Master Node MBP_REGISTER__UNSOLICITED MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW Path 1 Path 2 Number slave paths connected for MP Driver S Modbus Plus Master Node MBP_REGISTER__UNSOLICITED_V Paths 2 amp 3 Host Holding Register Path 1 Host Holding Registers MP Driver amp Modbus Plus Master Node MBP_HOST_WRITEABLE_REGION_V The PLC specifies which slave path is to be used in the second route parameter of the MSTR instruction If the mailbox option is used and the mailbox becomes full then the PLC is returned an error 10 MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW If the PLC wishes it may read from any of the paths from a single region if it is defin
76. x C Sample PLC MSTR MODBUS Plus VMS INTERFACE LIBRARY EXAMPLES C 1MSTR Example The following ladder diagram shows the use of the MSTR block within a PLC NETWORK 0005 Segment 01 This logic determines whether the NODE and PATH ultimately provided by the Level 2 system is valid This logic will enable or disable any MSTR instruction that generated the unsolicited messages to the Level 2 system based on the availability of the Level 2 system to provide the NODE and PATH Currently the NODE and PATH are merely hard coded into these registers for test purposes The Level system would probably clear these registers once per scan and recopy the values from the Level 2 write area If the registers remain cleared the Level 2 system is no longer available I I MBP NODE I NUMBER I FROM LVL2 I 1 I 40110 I MBP PATH I NUMBER I FROM LVL2 I 2 4 H u 1 00000 40111 I I JUNK NODE PATH I JUNK VALID I JUNK TRIGGER 3 SUB I 40012 00000 00999 T s 2 2 a I JUNK I JUNK I JUNK I 4 SUB I 40012 I Mile Ze 76 MODBUS Plus VMS INTERFACE LIBRARY EXAMPLES NETWORK 0006 Segment 01 These are the triggers for the MSTR instruction execution The instruction can be triggered by a valid NODE and PATH initialization see comment for network 5 manually with a contact from a forced coil or repetitively with a timer prov
77. y the master Modbus Node as the last route parameter Master paths in the VMS environment are allocated and managed by the device driver The paths allocated by the MBP_OPEN_NET are allocated from a free pool of which there are eight maintained by the driver see IO _ALLOC function in the Modicon DEC Host Based Devices User s Guide The actual allocated master and slave paths are stored in the process expanded region and returned to the caller by the MBP_OPEN_NET call Because the driver allocates the paths the paths may not be allocated sequentially All the routines documented in this manual that specify a path reference the path index Typically the path index will be equal to the actual path in a single program access system but not always This has little effect except for slave paths since the route array specifies the target PLC and there is no advantage to selecting a particular master path over another 1 8 Master Paths Each SQ85 or SA85 supports up to eight master paths The MBP_OPEN_NET allocates available master paths in sequential order A master path is used when the VAX is the master and the PLC or other remote Modbus Plus node is the slave Most functioning by the VAX uses the Master paths MODBUS Plus VMS INTERFACE LIBRARY OVERVIEW 1 9 Slave Paths Each SQ85 or SA85 supports up to eight slave paths The MBP_OPEN_NET allocates available slave paths in sequential order A slave path is used when the VAX is the sla

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