How To Read The Control Procedures Of The Mc Protocol - Mitsubishi MELSEC-F User Manual

8 COMMUNICATION USING MC PROTOCOL

8.1.2 How to Read the Control Procedures of the MC Protocol

External device side
PLC side
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This section explains the control procedures when an external device accesses the
PLC using MC protocol.
(1) Transmission of command messages
Data communication through the MC protocol is performed using half-duplex
communication.
When accessing the PLC, send the next command message after receiving a
response message from the PLC side for the previous command message
transmission.
(Command message)
(Response message)
(2) When a normal completion response message to a command
message cannot be received
1) If an abnormal completion response message is received
Handle the case according to the error code in the response message.
2) If the response message cannot be received or nothing can be received
Send the command message again after the monitoring time of the
response monitor timer.
Modify the value of the monitoring time as needed.
(Command message)
(Response message)
MELSEC-F
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