Mitsubishi Electric FR-F800 Series Instruction Manual page 514

 Signal loss detection (Pr.122, Pr.336 RS-485 communication check time
interval)
• If signal loss is detected between the inverter and computer, the communication error (PU connector communication:
E.PUE, RS-485 terminal communication: E.SER) will occur and the inverter output will be 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.
• Setting any value from 0.1 s to 999.8 s will enable signal loss detection. To detect signal loss, data must be sent from the
computer within the communication check time interval (for further information on control codes, refer to
inverter makes a communication check (clearing of communication check counter) regardless of the station number setting
of the data sent from the master.
• 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).
Computer
Inverter
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Example: PU connector communication, Pr. 122 = "0.1 to 999.8s"
External
Operation Mode
Inverter
Computer
Pr.122
Communication
check counter
ALM
search engine
PU
Check start
OFF
5.12 (N) Communication operation parameters
page 509). The
Fault (E.PUE)
Time
ON
5. PARAMETERS
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