Special Auxiliary Relays - Mitsubishi FX3U Series User Manual

FX Series Programmable Controllers
3U
User's Manual - MODBUS Serial Communication Edition
6.3

Special Auxiliary Relays

The table shows the Special Auxiliary Relays used for MODBUS serial communication.
Special Device
CH1
M8411
M8029
M8401 M8421
M8402 M8422
M8403 M8423
M8063 M8438
M8404 M8424
38
Name
CH2
MODBUS
Configuration
Request Flag
Command
Execution
Complete
MODBUS
Request in
Process
MODBUS
Communication
Error
MODBUS
Communication
Error (latched)
Listen Only
Mode
Valid Detailed Description
LD M8411 can be used to trigger a set of subsequent
MOV commands that initialize the MODBUS function.
M, S
Note: For details refer to Section 5.2.
This bit is turned on if the processing of a MODBUS
command is completed.
Special clear conditions:
1) Power on
M
2) STOP to RUN
3) If another command using M8029 is triggered
(including another MODBUS command)
Note: In the event of an error there will be one or
more of the error flags set.
If the MODBUS stack is processing a command no
further commands can be triggered until the current
request is completed and the Command Execution
Complete Flag is on.
M
Special clear conditions:
1) Power on
2) STOP to RUN
Set during the processing of the current MODBUS
command error.
Special clear conditions:
M, S
1) Power on
2) STOP to RUN
3) If another MODBUS command is triggered
Set once a MODBUS command error has been
processed.
M, S
Special clear conditions:
1) Power on
2) STOP to RUN
0: Normal processing
1: Listen only mode
Special clear conditions:
1) Power on
2) Reception of a restart command from the master
Note: Received messages are evaluated, but no
S
action takes place and no response is sent. The
only exception is the "reset communication
option" command (diagnosis 0x08 sub
command 0x01). If this command is received
the slave recovers from listen only mode
without sending a response, all subsequent
commands to this slave will be answered with a
response as usual.
6 Related Devices and Communication Status
6.3 Special Auxiliary Relays
R / W
R, W
R
R
R
R
R