Special Relays For Link - Mitsubishi MELSEC-A Series Programming Manual

APPENDICES
Appendix 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 special registers are applicable to all types of CPUs except the A3V.
For description of the special registers for link for the A3V, refer to the A3VTS Data Link
System User's Manual.
(1)
Number Name
LRDP instruction
M9200
received
LRDP instruction
M9201
complete
LWTP instruction
M9202
received
LWTP instruction
M9203
complete
Link parameter error
M9206
in the host
Link parameter
M9207 unmatched between
master station
Link card error
M9210
(master station)
M9224 Link status
M9225 Forward loop error
M9226 Reverse loop error
M9227 Loop test status
Link special relays only valid when the host is the master station
Table 1.2 Link Special Relay List
Description
OFF:Unreceived
ON: Received
OFF:Incomplete
ON: Complete
OFF:Unreceived
ON: Received
OFF:Incomplete
ON: Complete
OFF:Normal
ON: Error
OFF:Normal
ON: Unmatched
OFF:Normal
ON: Error
OFF:Online
ON: Offline, station-to-station
test, or self-loopback test
OFF:Normal
ON: Error
OFF:Normal
ON: Error
OFF:Unexecuted
ON: Forward or reverse loop
test being executed
• 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.
• 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.
• Depends on whether or not the LWTP (word device write)
instruction has been received.
• Used in the program as an interlock for the LWTP
nstruction.
• Use the RST instruction to reset.
• 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.
Depends on whether or not the link parameter setting of the
host is valid.
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.)
Depends on presence or absence of the link card hardware
error. Judged by the CPU.
Depends on whether the master station is online or offline or
is in station-to-station test or self-loopback test mode.
Depends on the error condition of the forward loop line.
Depends on the error condition of the reverse loop line.
Depends on whether or not the master station is executing a
forward or a reverse loop test.
APP - 13
Details