Mitsubishi Electric FX3U-ENET-ADP, Руководство пользователя

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7 Communication Using MC Protocol
48
FX
3U
-ENET-ADP User's Manual
7.2 Data Communication Function
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.
*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.
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.
Function name Send frame Communication data code Function Description
Communication using
MC protocol
A compatible 1E frame
ASCII code or
binary code
*1
Device memory
read/write Batch read/write in
bit/ word units
Remote control of the
PLC Remote RUN
Remote STOP
External device side
PLC side
(Command message) (Command message)
(Response message) (Response message)