How To Read The Control Procedures Of The Mc Protocol - Mitsubishi Electric FX3U-ENET User Manual

8 COMMUNICATION USING MC PROTOCOL
(2) Remote control of the PLC
Send frame
Communication A compatible 1E
using MC protocol frame.
*1 Time required for communication in binary code is shorter because the amount of communication data is
approximately a half of what is required for communication in ASCII code data.

8.1.2 How to Read the Control Procedures of the MC Protocol

This section explains the control procedures when an external device accesses the
PLC using MC protocol.
(1) Transmission of command messages
(Command message)
External device side
PLC side
(2) When a normal completion response message to a command
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This function executes remote RUN/STOP operations.
Remote operations of the PLC can be performed from the external device side.
Communication data code
ASCII code or binary code
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.
(Response message)
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.
Function
Device memory read/
write
*1
Remote control of the
PLC
(Command message)
(Response message)
MELSEC-F
Batch read/write in bit/
word units
Remote RUN
Remote STOP
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