I'm using the 1762-L24BXB model in conjunction with a fire alarm panel. The output in question is #2. With 24VDC applied to VDC2, outputs 2,3,4,5 and 6 function normally. I'm only using output 2, there are no connections to any other outputs mentioned above.

While in operation, if the 24VDC supply wire is removed from VDC2, and the wire is removed from outout #2, 8 VDC remains between VDC2 and common. If the contacts are closed via the software, the voltage goes away, as though an internal cap was discharged. it does not come back until voltage is once again applied to the VDC2 terminal.

I removed all the wires from the unit except unit power. The same thing happens when voltage is applied to VDC2, it stays there until the contacts for outputs 2-6 are closed. (when I say contacts I'm referring to the output in the logic)

I'm checking the ground right out when I finish typing this and take my break.

Anyone else seen this with the micrologix series?

Yoor probably seeing the leakage through the triac when the triac is off

I can't duplicate it on he bench. It only happens in the field.

I still think it's strange to see a voltage there with no wires attached until the output goes true.

This might be one for the geniuses at AB.

(I realize it's feedback through the triac but from what source?)