Modbus Rtu Communication Specification - Mitsubishi Electric FR-F820-04750 Instruction Manual

Parameters
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
N030
332
N031
334
N034
343
N080
539
N002
549
N000
NOTES 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 5-480.)
If a communication option is mounted with Pr. 550 "NET mode operation command source selec-
tion" = "9999 (initial value)", commands (operation commands) transmitted via RS-485 terminals
become invalid. (Refer to page 5-127.)
FR-F800
Name
RS-485 communication
station number
RS-485 communication
speed
RS-485 communication
parity check selection
Communication error
count
MODBUS RTU
communication check
time interval
Protocol selection
(N) Operation via communication and its settings
Initial Setting
Description
value range
0 Broadcast communication
0
Inverter station number specification
1 to 247
Set the inverter station numbers when two or more
inverters are connected to one personal computer.
Set the communication speed.
3, 6, 12, 24,
The setting value × 100 equals the communication
48, 96, 192,
96 speed.
384, 576,
For example, if 96 is set, the communication speed is
768, 1152
9600 bps.
Without parity check
0
Stop bit length 2 bits
With parity check at odd numbers
2 1
Stop bit length 1 bit
With parity check at even numbers
2
Stop bit length 1 bit
Displays the communication error count during
⎯
0
MODBUS RTU communication. Read-only.
MODBUS RTU communication, but the inverter trips
0
in the NET operation mode.
Set the interval of the communication check (signal
9999
0.1 to 999.8 s
loss detection) time. (same specifications as Pr. 122)
9999 No communication check (signal loss detection)
0 Mitsubishi inverter protocol (computer link)
0 1 MODBUS RTU protocol
2 BACnet MS/TP protocol
5 - 477