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Communication operation and setting
4
PARAMETERS
4.18.3 Operation selection at communication error occurrence (Pr.121, Pr.122, Pr.502)
(1) Retry count setting (Pr.121)
Set the permissible number of retries at data receive error occurrence. (Refer to page 213 for data receive error for retry)
When data receive errors occur consecutively and exceed the permissible number of retries set, a drive unit trips
(E.PUE) and a motor stops (as set in Pr.502).
When "9999" is set, a drive unit fault is not provided even if data receive error occurs but an alarm signal (LF) is output.
For the terminal used for the LF signal output, assign the function by setting "98 (positive logic) or 198 (negative logic)" in
any of Pr.190 to Pr.192 (output terminal function selection).
You can select the drive unit operation when a communication line error occurs during RS-485 communication from the
PU connector.
Parameter
number
Name
Initial
value
Setting
range
Description
121
Number of PU
communication retries
1
0 to 10
Number of retries at data receive error occurrence If the number of
consecutive errors exceeds the permissible value, the drive unit trips
(depends on Pr.502).
Valid only Mitsubishi inverter (computer link operation) protocol
9999 If a communication error occurs, the drive unit will not come to trip.
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 trips (depends on Pr.502).
9999 No communication check (signal loss detection)
502
Stop mode selection
at communication
error
0
At fault
occurrence
Indication Fault output
At fault
removal
0, 3 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
The above parameters can be set when Pr.160 Extended function display selection = "0". (Refer to page 182)
Computer
Example: PU connector communication, Pr.121 = "1" (initial value)
Example: PU connector communication, Pr.121 = "9999"
Reception error
Fault (E.PUE)
Drive unit
Drive unit
Computer
ENQ
ACK
NAK
NAK
Computer
LF OFF OFF
Drive unit
Drive unit
Computer
ENQ
ACK
NAK
NAK
ON
Wrong
Wrong
ENQ
ACK
Normal
ENQ
Wrong
ENQ
Wrong
ON
Reception error Reception error
OFF ONALM
Reception error