169
Communication operation and setting
4
PARAMETERS
(1) Retry count setting (Pr.121)
Set the permissible number of retries at data receive error occurrence. (Refer to page 178 for data receive error for retry)
When data receive errors occur consecutively and exceed the permissible number of retries set, an 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
Pr. 190 or Pr. 192 (output terminal function selection).
REMARKS
Pr. 121 is valid only when Mitsubishi inverter (computer link operation) protocol is selected. Pr. 121 is not valid when Modbus-
RTU communication protocol is selected.
How the drive unit operates at a communication error differs according to the Pr. 502 Stop mode selection at communication error
setting.
Computer
Reception error
Reception error
Fault (E. PUE)
Drive unit
Drive unit
Computer
ENQ
ACK
NAK
NAK
Computer
LF OFF OFF
Reception
error
Drive unit
Drive unit
Computer
ENQ
ACK
NAK
NAK
ON
Wrong
Wrong
ENQ
ACK
Normal
ENQ
Wrong
ENQ
Wrong
Example: PU connector communication, Pr. 121 = "1" (initial value)
Example: PU connector communication, Pr. 121 = "9999"
ON OFF
Reception
error
ALM ON
