Modbus Rtu - Mitsubishi Electric 800 Series Instruction Manual

3.5

MODBUS RTU

Operation or parameter setting via communication is possible using the MODBUS RTU communication protocol through the
PU connector on the inverter.
Pr.
117 PU communication
N020 station number
118 PU communication
N021 speed
PU communication
N023
stop bit length
PU communication
119 stop bit length / data
length
120 PU communication
N024 parity check
122 PU communication
N026 check time interval
343 Communication error
N080 count
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. To obtain replies from the inverter, set Pr.117 PU communication
station number ≠ "0 (initial value)".
• Some functions are disabled in broadcast communication. (Refer to
• If a communication option is installed with Pr.550 NET mode operation command source selection = "9999 (initial value)",
commands (operation commands) transmitted through the PU connector become invalid. (Refer to the FR-E800 Instruction
Manual (Function).)
• Always reset the inverter after making the initial settings of the parameters. After changing the communication-related
parameters, communication cannot be made until the inverter is reset.
 Communication specifications
• The communication specifications are shown in the following table.
Item
Communication protocol
Conforming standard
Number of connectable units
Communication speed
Control procedure
Communication method
142
3. RS-485 Communication
3.5 MODBUS RTU
Name Initial value
0
192
1
1
2
0
0
0
MODBUS RTU protocol
EIA-485 (RS-485)
1: N (maximum 32 units), setting is 0 to 247 stations
Selected among 4800/9600/19200/38400/57600/76800/115200 bps.
Asynchronous method
Half-duplex system
Setting
range
0 Broadcast communication
Specify the inverter station number.
1 to 247 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 96 to set the communication speed of 9600 bps.
0 Stop bit length 1 bit
1 Stop bit length 2 bits
0 Stop bit length 1 bit
1 Stop bit length 2 bits
10 Stop bit length 1 bit
11 Stop bit length 2 bits
Parity check disabled.
0 Stop bit length selectable between 1 bit and 2 bits (depending on the
setting of Pr.119).
Parity check (odd parity) enabled.
1
Stop bit length: 1 bit.
Parity check (even parity) enabled.
2
Stop bit length: 1 bit.
0 PU connector communication is disabled.
Set the interval of the communication check (signal loss detection)
0.1 to 999.8 time
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
Valid when Pr.N024 (Pr.120) = "0"
Valid when Pr.120 = "0"
144.)
Related parameter
Pr.549
—
Pr.117
Pr.118
—
—