FP-AI-111 input troubles

[TommyHelter]

Three inputs on two separate FP-AI-11 modules are malfunctioning (input signal confirmed) after likely being exposed to the same 24 vdc supply from the Vsupply terminals. I have experienced this problem once before and find it very disconcerting. Is there any more protection on this type of input on the Compact Field Point module?

TommyH

[Aaron_G]

Tommy,

The current versions of the FP-AI-111 and cFP-AI-111 are both rated for over-current protection of 30 mA. With an input impedance of 100 Ohms, this translates into 3 VDC, so shorting the 24 VDC supply to the input will destroy the input shunt resistor. The [c]FP-AIO-600 and [c]FP-AIO-610 modules have a wider over-current protection range on their inputs.

Regards,
Aaron

[TommyHelter]

Thank you. Much appreciated.

TommyH

[TommyHelter]

I looked at the specs for the 600 and the 610. It appears that there is only protection up to +/- 100 mA. So that's not going to do it either. Perhaps I will need to consider another component to provide the isolation I need.

Thanks again anyway,
TommyH