186
Communication operation and setting
4.16.6 Modbus-RTU communication specifications
(Pr. 117, Pr. 118, Pr. 120, Pr. 122, Pr. 343, Pr. 502, Pr. 549, Pr. 779)
Using the Modbus-RTU communication protocol, communication operation or parameter setting can be performed from
the PU connector of the drive unit.
Parameter
Number
Name Initial Value Setting Range Description
117
PU communication
station number
0
0 No reply to the master ∗1
1 to 247
Drive unit station number specification
Set the drive unit station numbers when two or more drive units
are connected to one personal computer.
118
PU communication
speed
192 48, 96, 192, 384
Communication speed
The setting value × 100 equals the communication speed.
Example) 9600bps if 96
120
PU communication
parity check
2
0
Without parity check
Stop bit length 2 bits
1
With odd parity check
Stop bit length 1 bit
2
With even parity check
Stop bit length 1 bit
122
PU communication
check time interval
0
0
RS-485 communication can be made. Note that a
communication fault (E.PUE) occurs as soon as the drive unit
is switched to the operation mode with command source.
0.1 to 999.8s
Communication check (signal loss detection) time interval
If a no-communication state persists for longer than the
permissible time, the drive unit is will come to trip (depends on
Pr. 502).
9999 No communication check (signal loss detection)
343
Communication error
count
0—
Displays the number of communication errors during Modbus-
RTU communication (reading only)
502
Stop mode selection
at communication
error
0
At Fault
Occurrence
Indication
Fault
Output
At Fault
Removal
0 Coasts to stop. E.PUE Output
Stop
(E.PUE)
1
Decelerates to
stop
After stop
E.PUE
Output after
stop
Stop
(E.PUE)
2
Decelerates to
stop
After stop
E.PUE
Without
output
Automatic
restart functions
3
Continues
running at
Pr. 779
⎯
Without
output
Operates in
normal
condition
549 Protocol selection
0
0 Mitsubishi inverter (computer link operation) protocol
1 Modbus-RTU protocol
779
Operation speed
during
communication error
9999
0 to 12000r/min/
0 to 8000r/min
∗2∗3
Motor runs at the specified speed at a communication error.
9999 Motor runs at the speed used before the communication error.
The above parameters can be set when Pr. 160 Extended function display selection = "0". (Refer to page 144)
∗1 When Modbus-RTU communication is performed from the master with address 0 (station number 0) set, broadcast communication is selected and the
drive unit does not send a response message. When response from the drive unit 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 189 )
∗2 Differs according to capacities. (0.2K to 2.2K/3.7K)
∗3 If a value exceeding 3000r/min is set, the actual rotation speed will be limited at 3000r/min.
NOTE
When "1" (Modbus-RTU protocol) is set in Pr. 549 and "384" (38400bps) in Pr. 118, parameter unit (FR-PU07) is
disabled. When using the parameter unit (FR-PU07), change parameter using the operation panel.