Why the analog values in the CM30 Effected when usind the digital inputs?
I do using the ABB CM30 controller in an application that i use two analog input channel each for a separate application
I do use digital inputs (Two) as an interlock per channel
event think i working correctly till the interlock occur
the values( the analog values) that the CM30 read are effected even if i have one digital input activated
I do read the values of the analog inputs in the diagnostic window , that values are effected very bad if the interlock occur
Voted best answer
This sounds as if there is some interaction between the digital inputs and the analogue signals. The ControlMaster CM30does not have any electrical isolation between the analogue inputs, the transmitter power supply and the digital input/outputs as detailed in the specification sheet. Depending on the precise wiring and circuit there may be some interaction when the digital input interlock is operated.
To be sure to get around this it may be sensible to use signal isolators on the analogue input channels and/or use volt free relay contacts on the digital inputs. Using volt free relay contacts on the digital inputs will ensure that the digital inputs are isolated from the CM30 circuit.