Mitsubishi FR-A740-00023-EC, Instruction Manual

Page: 343 / 474

333
Communication operation and setting
4
P
ARAME
T
E
R
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4.24.6 Modbus-RTU communication specifications (Pr. 331, Pr. 332, Pr. 334, Pr. 343,
Pr. 539, Pr. 549)
(1) Communication specifications
⋅
The communication specifications are given below.
Using the Modbus-RTU communication protocol, communication operation or parameter setting can be
performed from the RS-485 terminals of the inverter.
Parameter
Number
Name Initial Value Setting Range Description
331
RS-485 communication station
number
0
0 Broadcast communication is selected.
1 to 247
Specify the inverter station number.
Set the inverter station numbers when two
or more inverters are connected to one
personal computer.
332 RS-485 communication speed 96
3, 6, 12, 24, 48,
96, 192, 384
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".
334
RS-485 communication parity
check selection
2
0
Without parity check
Stop bit length 2bits
1
With odd parity check
Stop bit length 1bit
2
With even parity check
Stop bit length 1bit
343 Communication error count 0
⎯
Display the number of communication
errors during Modbus-RTU
communication. Reading only
539
Modbus-RTU communication
check time interval
9999
0
Modbus-RTU communication can be
made, but the inverter will come to an
alarm stop in the NET operation mode.
0.1 to 999.8s
Set the interval of communication check time.
(same specifications as Pr. 122 )
9999
No communication check (signal loss
detection)
549 Protocol selection 0
0
Mitsubishi inverter (computer link)
protocol
1 Modbus-RTU protocol
CAUTION
When Modbus-RTU communication is performed from the master with address 0 (station 0) set, broadcast communication is
selected and the inverter does not send a response message to the master.
When response from the inverter is necessary, set a value other than "0" in Pr. 331 (initial value 0).
Some functions are invalid for broadcast communication. (Refer to page 335)
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 310)
Item Description
Related
Parameters
Communication protocol Modbus-RTU protocol Pr. 549
Conforming standard EIA-485 (RS-485)
⎯
Number of inverters connected 1: N (maximum 32 units), setting is 0 to 247 stations Pr. 331
Communication speed Can be selected from 300, 600, 1200, 2400, 4800, 9600, 19200 and 38400bps Pr. 332
Control protocol Asynchronous system
⎯
Communication method Half-duplex system
⎯
Communication
specifications
Character system Binary(fixed to 8 bits)
⎯
Start bit 1bit
⎯
Stop bit length
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
Pr. 334
Parity check
Error check CRC code check
⎯
Terminator Not used
⎯
Waiting time setting Not used
⎯