Mitsubishi Electric FR-A700 Instruction Manual page 343

(6) Retry count setting (Pr. 121, Pr. 335)
⋅ Set the permissible number of retries at occurrence of a data receive error. (Refer to page 332 for data receive error
for retry)
⋅ When data receive errors occur consecutively and exceed the permissible number of retries set, an inverter alarm
(E.PUE) is provided and the output is shut off.
⋅ When "9999" is set, an inverter alarm is not provided even if data receive error occurs but a minor fault output 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. 196 (output terminal function selection).
Example: PU connector communication, Pr. 121 = "1" (initial value)
Operation mode
Computer
Inverter
Inverter
Computer
Example: PU connector communication, Pr. 121 = "9999"
Operation mode
Computer
Inverter
Inverter
Computer
LF
(7) Signal loss detection (Pr. 122, Pr. 336 RS-485 communication check time interval)
⋅ If a signal loss (communication stop) is detected between the inverter and computer as a result of a signal loss
detection, a communication error (PU connector communication: E.PUE, RS-485 terminal communication: E.SER)
occurs and the inverter output is shut off.
⋅ When the setting is "9999", communication check (signal loss detection) is not made.
⋅ When the setting is "0", communication from the PU connector cannot be performed. For communication via the RS-
485 terminals, monitor, parameter read, etc. can be peformed, but a communication error (E.SER) occurs as soon as
the inverter is switched to network operation mode.
⋅ A signal loss detection is made when the setting is any of "0.1s" to "999.8s". To make a signal loss detection, it is
necessary to send data (control code refer to page 331) from the computer within the communication check time
interval. (The send data has nothing to do with the station number)
⋅ Communication check is started at the first communication in the operation mode having the operation source (PU
operation mode for PU connector communication in the initial setting or network operation mode for RS-485 terminal
communication).
Example: PU connector communication, Pr. 122 = "0.1 to 999.8s"
Operation Mode
Computer
Inverter
Inverter
Computer
Pr. 122
Communication
check counter
Wrong
Reception error
Wrong
Reception error
OFF
External
PU
Check start
Communication operation and setting
Alarm (E.PUE)
Wrong
Reception error
Wrong Normal
Reception error
ON
Alarm(E.PUE)
OFF
Time
333
4