Reading a parameter cyclically

For the cyclic transmission method, the handshake bit has to be changed to activate service processing (execution of read service). When using acyclic PDU types, every inverter processes every request telegram and in this way always executes the parameter channel.

Parameters are set as follows:

1. Enter the index of the parameter to be read in byte 2 (index high) and byte 3 (index low).
2. Enter the service identifier for the READ service in the management byte (byte 0).
3. In cyclical PDU types, you transfer the read service to the inverter only by changing the handshake bit. In acyclical PDU types, the parameter channel is always evaluated.

Since this is a read service, the sent data bytes (bytes 4 - 7) and the data length (in the management byte) are ignored and do not need to be set.

The inverter now processes the read service and sends the service confirmation back by setting the handshake bit to an equal value.