Mitsubishi Electric FR-A820-00046 (0.4K) Instruction Manual page 644

 Retry count setting (Pr.121, Pr.335)
• Set the permissible number of retries at data receive error occurrence. (Refer to
• When the data receive errors occur consecutively and the number of retries exceeds the permissible number setting, a
communication fault (PU connector communication: E.PUE, RS-485 terminal communication: E.SER) occurs and the
inverter output is shut off.
• When a data transmission error occurs while "9999" is set, the inverter does not trip but outputs the Alarm (LF) signal. 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 an output terminal.
Example: PU connector communication, Pr. 121 = "1" (initial value)
Computer
Inverter
Inverter Computer
ALM
Example: PU connector communication, Pr. 121 = "9999"
Computer Inverter
Computer
Inverter
LF
ALM
NOTE
• For the RS-485 terminal communication, the operation at a communication error occurrence depends on the Pr.502 Stop
mode selection at communication error setting. (Refer to
 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.
• The LF signal is not output when a signal loss is detected. However, when a signal loss is detected via communication
through the RS-485 terminals while Pr.502 = "3 or 4", the LF signal is output.
• When the setting is "9999", communication check (signal loss detection) is not made.
• When the setting is "0", communication through the PU connector is not possible. The monitor items and parameter
settings can be read during communication via RS-485 terminals, but a communication error (E.SER) occurs instantly
when the operation mode is switched to the Network operation.
• A signal loss detection is made when the setting is any of "0.1 s to 999.8 s". To make a signal loss detection, it is necessary
to send data (for details on control codes, refer to
interval. (The inverter makes a communication check (clearing of communication check counter) regardless of the station
number setting of the data sent from the master).
Illegal
Reception error
Illegal
Reception error
OFF
page 640) from the computer within the communication check time
page 641
Fault (E.PUE)
Illegal
Reception error
ON
Illegal
Reception error
ON ON
OFF
page 630.)
5.15 (N) Communication operation parameters
for data receive error for retry.)
Normal
5. PARAMETERS
1
2
3
4
5
6
7
8
9
10
643