Accessing The Plc Using Mc Protocol; How To Read The Control Procedures Of The Mc Protocol - Mitsubishi Electric FX3U-ENET-ADP User Manual

FX -ENET-ADP User's Manual
3U
7.2.1

Accessing the PLC using MC protocol

This section explains the main functions for accessing the PLC using MC protocol.
On the PLC side, the Ethernet adapter sends and receives data based on instructions (protocol) from external
devices, so the PLC side does not require sequence programs for data communication.
1) Data read/write
This function reads/writes data from/to the PLC device memory to which the Ethernet adapter is
connected. By reading and writing data, the PLC operation monitoring, data analysis and production
management can be performed on the external device side.
2) Remote control of the PLC
This function executes remote RUN/STOP operations.
Remote operations of the PLC can be performed from the external device side.
Function name
Communication using
MC protocol
*1. Time required for communication in binary code is shorter because the amount of communication
data is approximately half of what is required for communication in ASCII code data.
7.2.2

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
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.
External device side
PLC side
2) When a normal completion response message to a command message cannot be received
a) If an abnormal completion response message is received
Handle the case according to the error code in the response message.
b) If the response message cannot be received or nothing can be received
Send the command message again after a period of time beyond the monitoring time of the response
monitor timer has passed.
Modify the value of the monitoring time as needed.
48
Send frame Communication data code
A compatible 1E frame
(Command message)
(Response message)
7 Communication Using MC Protocol
Function
Device memory
read/write
ASCII code or
*1
binary code
Remote control of the
PLC
(Command message)
7.2 Data Communication Function
Description
Batch read/write in
bit/ word units
Remote RUN
Remote STOP
(Response message)