Modbus-Rtu Communication Specifications (Pr. 331, Pr. 332, Pr. 334, Pr. 343, Pr. 549) - Mitsubishi Electric F700 Instruction Manual

3.18.6 Modbus-RTU communication specifications (Pr. 331, Pr. 332, Pr. 334, Pr. 343, Pr. 549)

Using the Modbus-RTU communication protocol, communication operation or parameter setting can be
performed from the RS-485 terminals of the inverter.
Parameter
Name
Number
331 RS-485 communication station
332 RS-485 communication speed
RS-485 communication parity
334
check selection
343 Communication error count
549 Protocol selection
The above parameters can be set when Pr. 160 User group read selection = "0". (Refer to page 140)
REMARKS
⋅ When using the Modbus-RTU protocol, set Pr. 549 Protocol selection to "1".
⋅ When the communication option is fitted with Pr. 550 NET mode operation command source selection set to "9999" (initial value),
the command source (e.g. run command) from the RS-485 terminals is invalid. (Refer to page 151)
(1) Communication specifications
⋅ The communication specifications are given below.
Item
Communication protocol
Conforming standard
Number of inverters connected
Communication speed
Control protocol
Communication method
Character
system
Start bit
Stop bit length
Communication
specifications
Parity check
Error check
Terminator
Waiting time setting
Initial Value Setting Range
0
3, 6, 12, 24, 48,
96
96, 192, 384
2
0
0
Description
Modbus-RTU protocol
EIA Standard RS-485
1: N (maximum 32 units), setting is 0 to 247 stations
Can be selected from 300, 600, 1200, 2400, 4800, 9600, 19200
and 38400bps
Asynchronous system
Half-duplex system
Binary(fixed to 8 bits)
Select from the following three types
⋅ No parity, stop bit length 2 bits
⋅ Odd parity, stop bit length 1 bit
⋅ Even parity, stop bit length 1 bit
CRC code check
Not used
Not used
Communication operation and setting
Description
Specify the inverter station number.
Set the inverter station numbers when
0 to 247
two or more inverters are connected to
one personal computer.
Set the communication speed.
The setting value × 100 equals the
communication speed.
For example, the communication
speed is 9600bps when the setting
value is "96".
Without parity check
0
Stop bit length 2bits
With odd parity check
1
Stop bit length 1bit
With even parity check
2
Stop bit length 1bit
Display the number of communication

errors during Modbus-RTU
communication. Reading only
Mitsubishi inverter (computer link)
0
protocol
1 Modbus-RTU protocol
1bit
Pr.268
page 100
Pr.333
page 161
Pr.335
page 161
Pr.342
page 162
Pr.495
page 98
Pr.504
page 213
Pr.550
page 151
Related
Parameters
Pr. 549

Pr. 331
Pr. 332


 3

Pr. 334



173