9-14
(3) Transmission procedure
1) Set communication functions H30 through H39.
2) Make communication according to transmission frames.
3) If no response returns for one second from the inverter upon a frame from the host, retry
communication. Several retries indicate certain errors. Make investigation.
4) If no communication is received from the host for 30 seconds after the first operation command is
received, the inverter judges a transmission breakdown error and shuts down the inverter output,
leaving the motor to coast to stop.
5) After consecutive eight communication errors, the inverter output is shut down and the motor coasts to
stop.
(4) Host controller transmission procedure
Do not send the next frame unless the response is returned.
If the inverter does not respond for longer than the standard time, timeout should be judged and retry
should be performed. If a retry is started before timeout, normal reception may become impossible,
so that timeout should be judged correctly. The timeout time is one second in the selecting mode and
0.5 second in the polling mode. In the retry sequence, send the same frame again as that sent
before no response, or send a polling (M26: communication error monitor) frame for reading an error,
and check for a normal response. (Judge the timeout again during the check.)
If a normal response is returned, a transient transmission error due to noise or the like is indicated,
and correct communication can be continued. If retries occur frequently, any abnormalities are
probable. In-depth investigation is necessary. If no response is returned, continue retrying. If there
are three retries, there is some trouble in the hardware or software of the host controller. Terminate
the software of the host controller and investigate.
No error code is returned in the case of negative acknowledgment of a short frame. Judge the error
code using the communication error monitor (M26) separately.
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