(N) Operation via communication and its settings
PARAMETERS
579
5
GROUP
N
5.15.6 Modbus-RTU communication specification
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 581.)
• 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 page 316.)
Communication specifications
• The communication specifications are given below.
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.
P
r. Name
Initial
value
Setting
range
Description
331
N030
RS-485 communication
station number
0
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.
332
N031
RS-485 communication
speed
96
3, 6, 12, 24,
48, 96, 192,
384, 576, 768,
1152
Set the communication speed.
The setting value 100 equals the communication speed.
For example, if 96 is set, the communication speed is 9600
bps.
334
N034
RS-485 communication
parity check selection
2
0
Without parity check
Stop bit length 2 bits
1
With parity check at odd numbers
Stop bit length 1 bit
2
With parity check at even numbers
Stop bit length 1 bit
343
N080
Communication error
count
0
Displays the communication error count during Modbus-RTU
communication. Read-only.
539
N002
Modbus-RTU
communication check
time interval
9999
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)
549
N000
Protocol selection
0
0 Mitsubishi inverter protocol (computer link)
1 Modbus-RTU protocol
Item Description
Related
parameter
Communication protocol Modbus-RTU protocol Pr.549
Conforming standard EIA-485 (RS-485)
Connectable units 1:N (maximum 32 units), setting is 0 to 247 stations Pr.331
Communication Speed
Selected among 300/600/1200/2400/4800/9600/19200/38400/57600/76800/
115200 bps
Pr.332
Control procedure Asynchronous system
Communication method Half-duplex system
Communication
specifications
Character system Binary (fixed at 8 bits)
Start bit 1 bit
Stop bit length
Select from the following three types:
No parity check, stop bit length 2 bits
Odd parity check , stop bit length 1 bit
Even parity check, stop bit length 1 bit
Pr.334
Parity check
Error check CRC code check
Terminator Not used
Waiting time setting Not used
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