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4.19.6 MODBUS RTU communication specifications
(Pr. 117, Pr. 118, Pr. 120, Pr. 122, Pr. 343, Pr. 502, Pr. 549)
Using the MODBUS RTU communication protocol, communication operation or parameter setting can be performed
from the PU connector of the inverter.
Parameter
Name
Number
PU communication
117
station number
PU communication
118
speed
PU communication
120
parity check
PU communication
122
check time interval
Communication error
343
count
Stop mode selection
502
at communication
error
549
Protocol selection
The above parameters can be set when Pr. 160 Extended function display selection = "0". (Refer to page 165.)
* When MODBUS RTU communication is performed from the master with address 0 (station number 0) set, broadcast communication is selected and the
inverter does not send a response message. When response from the inverter is necessary, set a value other than "0" (initial value is 0) in Pr. 117 PU
communication station number.
Some functions are invalid for broadcast communication. (Refer to page 204.)
NOTE
When "1" (MODBUS RTU protocol) is set in Pr. 549 and "384" (38400bps) in Pr. 118, parameter unit (FR-PU04/FR-PU07)
is disabled. When using the parameter unit (FR-PU04/FR-PU07), change parameter using the operation panel.
REMARKS
Set Pr. 549 Protocol selection to "1" to use the MODBUS RTU protocol.
When PU connector is selected as NET mode operation source (when Pr. 551 PU mode operation command source selection "2"),
MODBUS RTU communication operation can be performed. (Refer to page 177.)
Communication operation and setting
Setting
Initial Value
Range
0
No reply to the master *
Inverter station number specification
0
1 to 247
Set the inverter station numbers when two or more inverters are
connected to one personal computer.
Communication speed
48, 96, 192,
The setting value 100 equals the communication speed.
192
384
Example) 9600bps if 96
Without parity check
0
Stop bit length 2 bits
With odd parity check
2
1
Stop bit length 1 bit
With even parity check
2
Stop bit length 1 bit
RS-485 communication can be made. Note that a communication
0
fault (E.PUE) occurs as soon as the inverter is switched to the
operation mode with command source.
0
Communication check (signal loss detection) time interval
0.1 to
If a no-communication state persists for longer than the permissible
999.8s
time, the inverter will come to trip (depends on Pr. 502).
9999
No communication check (signal loss detection)
Displays the number of communication errors during MODBUS RTU
0
—
communication (reading only)
At Fault
Occurrence
0
Coasts to stop. E.PUE
0
Decelerates to
1
stop
Decelerates to
2
stop
0
Mitsubishi inverter (computer link operation) protocol
0
1
MODBUS RTU protocol
Description
Indication
Fault Output
Output
After stop
Output after
E.PUE
stop
After stop
Without output
E.PUE
At Fault
Removal
Stop
(E.PUE)
Stop
(E.PUE)
Automatic
restart functions
4
201
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