Modbus Rtu Communication Specification - Mitsubishi Electric FR-CS84-012 Instruction Manual

5.11.5 MODBUS RTU communication specification

Through communication using the MODBUS RTU communication protocol via the PU connector on the inverter, inverter
operation and parameter setting are available.
Pr.
117 PU communication station
N020 number
118
PU communication speed
N021
PU communication stop bit
119
length / data length
120 PU communication parity
N024 check
122 PU communication check
N026 time interval
343
Communication error count
N080
549
Protocol selection
N000
NOTE
• To use the MODBUS RTU protocol, set "1" in 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.
• Some functions are disabled in broadcast communication. (Refer to
 Communication specifications
• The communication specifications are given below.
Item
Communication protocol
Conforming standard
Number of connectable units
Communication speed
Control procedure
Communication method
Character
system
Start bit
Communic
Stop bit length
ation
specificati
Parity check
ons
Error check
Terminator
Time delay setting
182
5. PARAMETERS
5.11 (N) Communication operation parameters
Initial
Name
value
0
192
1
2
9999
0
0
MODBUS RTU protocol
EIA-485 (RS-485)
1: N (maximum 32 units), setting is 0 to 247 stations
Selected among 300/600/1200/2400/4800/9600/19200/38400/57600/76800/
115200 bps
Asynchronous method
Half-duplex system
Binary (fixed at 8 bits)
1 bit
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
CRC code check
Not available
Not available
Setting
range
Specify the inverter station number.
0 to 31 Enter the inverter station numbers when two or more inverters are
connected to one personal computer.
48, 96, 192, Select the communication speed.
384, 576, The setting value × 100 equals the communication speed.
768, 1152 For example, enter 192 to set the communication speed of 19200 bps.
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
1 With parity check at odd numbers
2 With parity check at even numbers
0 PU connector communication is disabled.
Set the interval of the communication check (signal loss detection)
time
0.1 to 999.8 s
If a no-communication state persists for longer than the permissible
time, the inverter output will be shut off.
9999 No communication check (signal loss detection)
Displays the communication error count during MODBUS RTU
—
communication. Read-only.
0 Mitsubishi inverter protocol (computer link)
1 MODBUS RTU protocol
page
Description
Description
Data length 8 bits
Data length 7 bits
184.)
Pr.549
̶
Pr.117
Pr.118
̶
̶
̶
̶
Pr.120
̶
̶
̶
Related
parameter