1794-OE4 Flex I/O problem.

Hi all, I have a system that consists of a PLC 5/40E and some 1794 flex I/O. This system has worked seamlessly for years and nothing has been changed recently. I have two 1794-0E4 analogue output modules along with three 1794-IB16 input modules in my remote I/O. The analogue output modules are intermittently locking up,(values present in block transfer, but no voltage output) no fault indication in hardware or software apparent. Block transfer instructions are functioning and commanding output values ok. I have swapped out the two modules to no avail.

Kind regards.

Vern1

Have you tried swapping out the 1794-ASB module?

When you get a no voltage situation what are you doing to recover?

I've also seen rare cases where the TB3 terminal blocks have gone bad due to a one time short or other factor (corrosion perhaps) so you might try swapping the terminal base too.

Hi Robertmee, To recover I just cycle the power on the 1794-ASB. Have not tried swapping it yet.

Regards.

Vern1

Are you using a 1771-SN card or the port on the processor.

We had the same problem when using the 1771-SN with "new" flex I/O modules. We had to cyle power to restore comms every time we saw a power blip. Apparently the new flex I/O was not "totally" compatible with the SN card.

After moving the network off of the card and onto the port on the processor there were no more issues.