I'm having this problem with my Modbus TCP master program: a successful connection is made to the server, to be used to read a number of input registers in sequence by using the ModbusFB.ClientRequestReadInputRegisters function block.
But although the xExecute input is being controlled by a clock signal which turns it ON and OFF cyclically, no ModbusTCP request has ever been sent onto the physical ethernet medium. At the same time, I get no Error or Exception messages from any ModbusTCP function block. However, the ClientTCP.udiNumReqNotProcessed keeps rising, hinting at something called request starvation (at least according to the official documentation). Is there some extra action that I need to take to make the ModbusFB.ClientRequestReadInputRegisters FB send these requests out apart from setting appropriate values at its inputs and outputs?
Please see the attached screenshots.
Talk Topic about project #codesys-example/modbus
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