Mitsubishi Electric 800 Series Instruction Manual page 501

5.12.6 MODBUS RTU communication specification
Operation by MODBUS RTU communication or parameter setting is possible by using the MODBUS RTU communication
protocol from the RS-485 terminals of the inverter.
Pr.
331 RS-485 communication
N030 station number
332 RS-485 communication
N031 speed
N033 RS-485 communication stop
bit length
333 RS-485 communication stop
bit length / data length
334 RS-485 communication
N034 parity check selection
343 Communication error count
N080
539 MODBUS RTU
N002 communication check time
interval
549 Protocol selection
N000
NOTE
• To use the MODBUS RTU protocol, set "1" to Pr.549 Protocol selection.
• If MODBUS RTU communication is performed from the master to the address 0 (station number 0), the data is
broadcasted, and the inverter does not send any reply to the master. To obtain replies from the inverter, set Pr.331 RS-
485 communication station number  "0 (initial value)". Some functions are disabled in broadcast communication. (Refer
to page 503.)
• If a communication option is mounted with Pr.550 NET mode operation command source selection = "9999 (initial
value)", commands (operation commands) transmitted via RS-485 terminals become invalid. (Refer to
500
5. PARAMETERS
5.12 (N) Operation via communication and its settings
Name Initial
value
0
96
1
1
2
0
9999
0
Setting range
0 Broadcast communication
1 to 247 Inverter station number specification
Set the inverter station numbers when two or more inverters are
connected to one personal computer.
3, 6, 12, 24, Set the communication speed.
The setting value  100 equals the communication speed.
48, 96, 192,
384, 576, 768, For example, if 96 is set, the communication speed is 9600 bps.
1152
0 Stop bit length 1 bit
1 Stop bit length 2 bits
0 Stop bit length 1 bit
1 Stop bit length 2 bits
10 Stop bit length 1 bit
11 Stop bit length 2 bits
0 Without parity check
Stop bit length 1 bit / 2 bits (depends on the setting of Pr.333)
1 With parity check at odd numbers
Stop bit length 1 bit
2 With parity check at even numbers
Stop bit length 1 bit
― Displays the communication error count during MODBUS RTU
communication. Read-only.
0 MODBUS RTU communication, but the inverter trips in the NET
operation mode.
0.1 to 999.8 s Set the interval of the communication check (signal loss
detection) time (same specifications as Pr.122).
9999 No communication check (signal loss detection)
0 Mitsubishi inverter protocol (computer link)
1 MODBUS RTU protocol
2 BACnet MS/TP protocol
Description
Valid when Pr. N034 (334) = "0"
Valid when Pr. 334 = "0"
page 214.)