MX2N series HMI PLC all in one programming manual
9 MX2N-70HB Optional com port instructions
9.1 Function Description
1) MX2N-70HB supports the optional 1 RS485 communication port, but can not coexist with
its own 232 port.
2) Support exchange between Mitsubishi programming protocol and MODBUS-RTU
protocol. (When PLC stops, it will be back to Mitsubishi programming protocol; When PLC
start, the protocol depends on D8120.)
3) Communication data of optional communication port is set in the D8120 and it will take
effect after PLC runs (the modification could be made until the STOP-RUN is valid again
when the PLC is in effect, the D8120 is reset to 0 when the PLC is in STOP), and the
MODBUS-RTU slave station number is set in the D8121 ( Range 1~255).
4) Use FROM to read slave data when using MODBUS-RTU master, to write slave data
(supports broadcast sending function)
5) Set the optional communication port to MODBUS-RTU protocol. the baud rate of slave is
9600 . as follows:
9.2Modbus-RTU Protocol special registers & relays
Master：
M8121-Master data transmission.
M8122-Master receive Slave data, check error.
M8123-Master receive completed signal
M8124-Master receive broadcast signal
M8129-Communication timeout signal
D8120-Communication parameter and function
D8126-Sending interval(1=1ms,default 20ms，interval between two communication)
D8122-Station number with communication timeout
D8123-Real receiving time（1=10ms）
D8124-Max receiving time(1=10ms)
D8129-Receive timeout setting （1=10ms，default 50=500ms，Time from sending completed
to receiving completed）
Slave:
D8120-Communication parameters and function
D8121-Slave address（Range：1~255）
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