Input card giving off Power

[thekokiko]

I have a 5069-IB16 card on a rack controlled by a 5069-L320ERS2 (Safety Controller). For whatever reason I am getting a voltage reading coming out of the input itself of 16 volts. I removed the wire from the input and measured it directly from the input to 0V.

Any idea what could be causing this because I'm suspecting it now messing with me inputs.

 

[I_Automation]

Unused inputs, discreet and analog, can have leakage going though the transistors.

That's why a lot of analog inputs say to short out unused inputs to common.

Connect a device to the input and see if that voltage goes away.

Don't forget, DMM's don't drain like old VTVM meters and "wiggie's" did so they read voltages that won't be there under use.

 

[thekokiko]

So its a safety controller (guardlogix). the slot i've been checking is slot 3. i checked i on an input from slot 2 and it was around 12 volts and then an input from slot 1 and it was 5 volts. not sure if that is helpful information but just what i found. the issue i was having was that when an input was wired in and sending 24v to the input card, the input didn't come on. i figure because theres voltage fighting it and dropping it below the threshold for it to trigger.

 

[I_Automation]

Yes!

Safety inputs send out pulses to the device and check for current flow to detect the device is still there and no wire broke. Safety outputs also do this but with a voltage small enough to not trigger the device.

Those are designed that way and will not effect other inputs, the device or how the device is read.

 

[thekokiko]

okay but these cards aren't safety cards. its a safety controller with 3 regular digital inputs cards 2 digital output cards 2 analog input cards 1 analog output and then the safety input and output at the end.

I also found that when i turned off an MCP the voltages drop down to 5 volts instead. not sure how those would be related but who knows

 

[5618]

Hi, neighbor. That sounds like SA power is somehow incorrect. Are your outputs AC that would need a separate SA power feed from a FPD? Is the power supply negative grounded?. If you’re reading from ground and your 24V- isn’t grounded, you could read a variety of random voltages. I fired up almost your same setup for the first 8 modules with only MOD and SA power connected and see less than 0.9 volt on inputs. It seems to drop a bit with more modules connected and seems to drop as the system warms after power up.