Sign in to follow this  
Followers 0
Calle

SLC 500 I/O module become unstable (spiky values)

2 posts in this topic

Hello

I have a bunch of MFCs that are controlled via AB SLC 500 analog combination I/O modules (1746-NI4O). After some time they tend to become spiky and cant hold a certain value. I have maybe 20 cards with this problem. The machine was installed 1994 so it is not so surprising. But does anyone know or have any suggestions about how they usually break down and how to fix them.

 

Kind regards Calle

Share this post


Link to post
Share on other sites

I would try to isolate the problem a little more. If it's a noisy input, then remove your signal and give it a known source. You can put a resistor from a power supply in series with the input and then watch the value in rslogix.

If it's a noisy output, then poke a value into the output address and measure the output with nothing else connected( you'll need a resistor of course if it's a current output).

My guess is that if you're talking about an input, it's the device sending the signal to the plc and not the module.  I've used a lot of these older products and I still have customers that have systems from  the early 90's that are still going strong.

Run some tests and let us know what's happening.

 

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0