Mitsubishi Electric FR-D720-0.2K-G Instruction Manual page 189

Communication operation and setting
(1) Retry count setting (Pr.121)
Set the permissible number of retries at data receive error occurrence. (Refer to page 195 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 (LF) signal 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).
Example: PU connector communication, Pr. 121 = "1" (initial value)
Computer
Drive unit
Drive unit
Computer
ALM
Example: PU connector communication, Pr. 121 = "9999"
Computer
Drive unit
Drive unit
Computer
LF
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.
186
Wrong
Reception error
Wrong
OFF
Fault (E. PUE)
Wrong
Reception error
ON
Wrong
Reception Reception
error error
ON OFF ON
Normal
OFF