Rslogix500 input issue

Hey guys, first time poster here and very new to the PLC world, i'll cut to the point:

I am using the rslogix 500 program and i have a photo-eye attached to an XIC bit in my program. I've been having issues with the process recently so i looked to the program and found that the bit that the eye is attached to seems to be flickering very subtlety, before i go trying to change out some photo-eyes my question is ; is this very faint flickering enough to disable my output? it goes on and out multiple times within milliseconds!

Welcome to the PLCTalk forum !

When you say that the "bit" is flickering, do you mean the indicator on the Input module?

You're either seeing rapid switching of the input state, or a low voltage that is hovering around the 1 vs. 0 threshold.

Either way, start by checking for loose wires (both power and common and signal).

A "flickering" input can definitely cause your logic to not work the way you expect.

+1 For Ken's suggestion. In my experience the problem is almost always the field device or the cable going to it. If this process has been running for more than 6 month, and no changes have been made to the program recently, there is a 99.99% chance that the problem is a bad eye or bad cable. You mentioned flickering, so I'm going to guess bad cable.

Bubba.

PS...
Welcome to the forum!