Mitsubishi Electric FR-A820-00046 Instruction Manual page 829

Parameters
Setting the communication protocol (Pr. 549)
● Select the communication protocol.
● The Modbus® RTU protocol can be used by communication from the RS-485 terminals (from the
Ethernet connector for FR-A800-E).
Tab. 5-271: Protocol selection
Communication EEPROM write selection (Pr. 342)
● When parameter write is performed via the inverter PU connector, RS-485 terminal, USB commu-
nication, the Ethernet connector (FR-A800-E only), or a communication option, the parameters
storage device can be changed from EEPROM + RAM to RAM only. Use this function if parameter
settings are changed frequently.
● When changing the parameter values frequently, set "1" in Pr. 342 "Communication EEPROM write
selection" to write them to the RAM only. The life of the EEPROM will be shorter if parameter write
is performed frequently with the setting unchanged from "0 (initial value)" (EEPROM write).
NOTES Turning OFF the inverter's power supply clears the modified parameter settings when Pr. 342 = "1
(write to RAM only)". Therefore, the parameter values at next power-ON are the values last stored
in EEPROM.
The parameter setting written in RAM cannot be checked on the operation panel. (The values dis-
played on the operation panel are the ones stored in EEPROM.)
Operation selection at a communication error (Pr. 502, Pr. 779)
● For communication using RS-485 terminals, via the Ethernet connector (FR-A800-E only) , or a
communication option, operation at a communication error can be selected. The operation is
active under the Network operation mode.
● Select the stop operation at the retry count excess (Pr. 335, only with Mitsubishi inverter protocol)
or at a signal loss detection (Pr. 336, Pr. 539).
● For FR-A800-E: The operation at a communication error can be selected with Pr. 502 when Pr. 1431
"Ethernet signal loss detection function selection" = "3" or Pr. 1432 "Ethernet communication
check time interval" ≠ "9999" during Ethernet communication.
● When a communication error is detected while communication with the RS-485 terminals is
performed, the alarm (LF) signal is output to an output terminal of the inverter.To use the LF signal,
set "98 (positive logic) or 198 (negative logic)" in any of Pr. 190 to Pr. 196 (output terminal function
selection) to assign the function to the output terminal.
(To output the LF signal even if communication through RS-485 terminals is not performed for
the time set in Pr. 336 or longer, or during communication using a communication option, set "3
or 4" in Pr. 502.)
● For FR-A800-E: When a communication error is detected during communication via the Ethernet
connector while Pr. 1431 "Ethernet signal loss detection function selection" = "2 or 3", the alarm
(LF) signal is output to an output terminal of the inverter.
To use the LF signal, set "98 (positive logic) or 198 (negative logic)" in any of Pr. 190 to Pr. 196
(output terminal function selection) to assign the function to the output terminal. (While com-
munication is performed with a communication option, LF signal is output only when "3 or 4" is
set in Pr. 502.)
FR-A800
Pr. 549 setting Communication protocol
0(initial value) Mitsubishi inverter protocol (computer link)
1 Modbus® RTU protocol
(N) Operation via communication and its settings
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