APPENDIX 1 SPECIAL RELAYS AND SPECIAL REGISTERS
1.2 Special Relays for Link
The link special relays are internal relays which are switched on/off by various factors occurring during data link operation.
Their ON/OFF status will change if an error occurs during normal operation.
These relays are applicable to all types of CPUs except the A3VCPU.
For description of the special relays for link for the A3VCPU, refer to the A3VTS Data Link System User's Manual.
(1) Link special relays only valid when the host is the master station Table 1.2 Link Special Relay List (Continue)
Number Name Description Details
M9200 LRDP instruction received
OFF: Unreceived ON: Received
• Depends on whether or not the LRDP (word device read) instruction has been received.
• Used in the program as an interlock for the LRDP instruction.
• Use the RST instruction to reset.
M9201 LRDP instruction complete
OFF: Incomplete ON: Complete
• Depends on whether or not the LRDP (word device read) instruction execution is complete.
• Used as a condition contact for resetting M9200 and M9201 after the LRDP instruction is complete.
• Use the RST instruction to reset.
M9202 LWTP instruction received
OFF: Unreceived ON: Received
• Depends on whether or not the LWTP (word device write) instruction has been received.
• Used in the program as an interlock for the LWTP instruction.
• Use the RST instruction to reset.
M9203 LWTP instruction complete
OFF: Incomplete ON: Complete
• Depends on whether or not the LWTP (word device write) instruction execution is complete.
• Used as a condition contact to reset M9202 and M9203 after the LWTP instruction is complete.
• Use the RST instruction to reset.
M9206 Link parameter error in the host
OFF: Normal ON: Error
Depends on whether or not the link parameter setting of the host is valid.
M9207
Link parameter unmatched between master station
OFF: Normal ON: Unmatched
Depends on whether or not the link parameter setting of the master station in tier two matches that of the master station in tier three in a three-tier system.
(Valid only for the master stations in a three-tier system.) M9210 Link card error
(master station)
OFF: Normal ON: Error
Depends on presence or absence of the link card hardware error. Judged by the CPU.
M9224 Link status
OFF: Online
ON: Offline, station-to- station test, or self- loopback test
Depends on whether the master station is online or offline or is in station-to-station test or self-loopback test mode.
M9225 Forward loop error OFF: Normal
ON: Error Depends on the error condition of the forward loop line.
M9226 Reverse loop error OFF: Normal
ON: Error Depends on the error condition of the reverse loop line.
M9227 Loop test status
OFF: Unexecuted ON: Forward or reverse
loop test being ex- ecuted
Depends on whether or not the master station is executing a forward or a reverse loop test.
M9232 Local station operating status
OFF: RUN or STEP RUN mode ON: STOP or PAUSE mode
Depends on whether or not a local station is in STOP or PAUSE mode.
Table 1.2 Link Special Relay List
Number Name Description Details
M9233 Local station error detect
OFF: No error ON: Error detected
Depends on whether or not a local station has detected an error in another station.
M9235
Local or remote I/O station parameter error detect
OFF: No error ON: Error detected
Depends on whether or not a local or a remote I/O station has detected any link parameter error in the master station
M9236
Local or remote I/O station initial communicating status
OFF: Noncommunicating ON: Communicating
Depends on whether or not a local or a remote I/O station is communicating initial data (such as parameters) with the master station.
M9237 Local or remote I/O station error
OFF: Normal
ON: Error Depends on the error condition of a local or remote I/O station.
M9238
Local or remote I/O station forward/
reverse loop error
OFF: Normal ON: Error
Depends on the error condition of the forward and reverse loop lines of a local or a remote I/O station.
(2) Link special relays only valid when the host is a local station Table 1.3 Link Special Relay List
Number Name Description Details
M9204 LRDP instruction complete
OFF: Incomplete ON: Complete
On indicates that the LRDP instruction is complete at the local station.
M9205 LWTP instruction complete
OFF: Incomplete ON: Complete
On indicates that the LWTP instruction is complete at the local station.
M9211 Link card error (local station)
OFF: Normal ON: Error
Depends on presence or absence of the link card error.
Judged by the CPU.
M9240 Link status
OFF: Online
ON: Offline, station-to- station test, or self- loopback test
Depends on whether the local station is online or offline, or is in station-to-station test or self-loopback test mode.
M9241 Forward loop error OFF: Normal
ON: Error Depends on the error condition of the forward loop line.
M9242 Reverse loop error OFF: Normal
ON: Error Depends on the error condition of the reverse loop line.
M9243 Loopback execution OFF: Non-executed ON: Executed
Depends on whether or not loopback is occurring at the local station.
M9246 Data unreceived OFF: Received ON: Unreceived
Depends on whether or not data has been received from the master station.
M9247 Data unreceived OFF: Received ON: Unreceived
Depends on whether or not a tier three station has received data from its master station in a three-tier system.
M9250 Parameter unreceived
OFF: Received ON: unreceived
Depends on whether or not link parameters have been received from the master station.
M9251 Link break OFF: Normal
ON: Break Depands on the data link condition at the local station.
M9252 Loop test status
OFF: Unexecuted ON: Forward or reverse
loop test is being executed
Depends on whether or not the local station is executing a forward or a reverse loop test.
M9253 Master station operating status
OFF: RUN or STEP RUN mode ON: STOP or PAUSE mode
Depends on whether or not the master station is in STOP or PAUSE mode.
M9254 Operating status of other local stations
OFF: RUN or STEP RUN mode ON: STOP or PAUSE mode
Depends on whether or not a local station other than the host is in STOP or PAUSE mode.
M9255 Error status of other local stations
OFF: Normal ON: Error
Depends on whether or not a local station other than the host is in error.