Hi all,

I am setting up our DT80 to communicate with a plant's Citect SCADA system via MODBUS.

The unit is communicating with the system fine, as some values are being displayed while some are not.

We are trying to display 5 different numbers, each assigned to a CV within the DT80.

My question is in regard to the Modbus registers and what determines an input or an output register?

From the manual;
input reg, 1-800, 30001-30800
output reg, 1-800, 40001-40800
'returns current value of channel variable 1..800CV

It seems as though readings which are being measured from 2 probes are working on the SCADA, but any calculated entries are not working. Is this because for example the sensors give an input register value while the calculated values are an output register?

Any help is greatly appreciated,

Nick

Good morning Nick,

What date types are you using?
If your using a Long Int or a float then they use 2 registers

I think you should look at the Modbus slave document in the training section:
https://datatakerforum.com/Documents/Notes/TR-0012-RD%20-%20Modbus%20Slave.pdf

It has some worked examples that should assist you.

Cheers,
Roger