Signal loss detection (Pr.122)
• If a signal loss (communication stop) is detected between the inverter and computer as a result of a signal loss detection,
a communication error (E.PUE) occurs and the inverter output will be shut off.
• The LF signal is not output when a signal loss is detected.
• 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.
• 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).
• For communication via the PU connector, communication check is started at the first communication in the PU operation
• When data from the computer has any error, the inverter does not accept that data. Hence, in the user program, always
insert a retry program for data error.
• All data communication, for example, run command or monitoring, are started when the computer gives a communication
request. The inverter does not return any data without the computer's request. Hence, design the program so that the
computer gives a data read request for monitoring, etc. as required.
• Program example: To switch to the Network operation mode
5.11 (N) Communication operation parameters
Example: PU connector communication, Pr. 122 = "0.1 to 999.8s"
172) from the computer within the communication check time