Micrologix IO cards Error

Hi

I have a Micrologix 1400 with some external IO cards, the costumer complains about failing IO cards, especially the Analog Output card is replaced often (once every 18 months) I haven't worked that much with the Micrologix, so I don't know if there is any special things to look for.

Temperature and external power supply looks OK

Are the Micrologix external IO especially sensitive ?

Any input would be great

Thanks
/Holmux

They're generally pretty reliable but they do fail now and then. Like after 10 years or so. If he's got consistently failing cards I would check to make sure there's not some terrible noise or 240VAC riding on the DC bus or some other shenanigans.

I think you are right, I am also leaning against quality a power source problem.

Well I have been looking a bit on the setup, there is a lot of static electricity going around in the operation, so I will start with measuring the quality of the power and ground going true this cabinet.

That means I will need to go and get me some new tools, I have been looking for an excuse to get my self a portable oscilloscope for a long time, Christmas came early this year

Make sure you have a GOOD ground to the ML1400 and it is mounted on steel din rail NOT aluminium din rail.

Alan

alan_505 said:

and it is mounted on steel din rail NOT aluminium din rail.

Alan

Click to expand...

Why?

See link.. There is a paragraph about dissimilar metals. Is that your reason?

https://www.designnews.com/electronics-test/din-rail-basics/151128668527601

We had a couple panels where analog input values and output levels would randomly freeze until a power cycle. The Flex IO racks were mounted to aluminum rail. None of the ground tabs on the module bases or the ASB pierced the oxide layer on the rail to actually be grounded. A switch to steel rail resolved the problem.