Hello
Yes, I have fully read it and that is why I had my questions about Modbus. In the meanwhile, I was able to get out the needed information by misregarding the text about adding 30000 or 40000 to the vector address (which is simply not true because by using the different Modbus commands there is nothing to add). So,
ReadCoils(4001,2) works. And so does ReadDiscreteInputs(4001,2) giving the same result. The same is true for ReadCoils(5001,2) and ReadDiscreteInputs(5001,2). And that is a bit confusing as ReadDiscreteInputs is supposed to be available to read inputs, while ReadCoils is for setting and reading outputs. But anyway, the good news is that it works! Thanks for your reply!