SLC tags communications lost

On version 7.5.6 and just had an issue with 10 or so tags from an SLC going to ‘unreachable’ red crosses etc although another 10 in the PLC were reading correct.
Disabling a tag and re-enabling cured it as did doing the same for the PLC connection as a whole.
The SLC is being read through a MOXA gateway onto Ethernet.

Is there any explanation as to what could have caused this? No PLC mods occured in this PLC.

Are those 10 tags in a different scan class than the rest?

No, every tag from that PLC has default scan rate. I THINK looking at the screen and what was over laid with bad comms everything lost was a float but I didn’t take a screenshot etc.

You can send your logs into support and we’ll take a look, but it sounds more like something that needs to be diagnosed WHILE it’s happening, so if happens again and you can call in and let the support guys look that would be even better.

What model slc are you using and what moxa model? Just curious I recently purchased for testing a gw1000 gateway from data link technologies for a slc 5/04 over dh+… just curious about your hardware…

Its a Moxa EIP3000 DF1 to Ethner/IP Gateway going to a SLC5/04 (channel 0). Been in around 8 months and has been trouble free so far. Only problem is this is not the first PLC to have been dropped from Ignition requiring a disable/enable. The other SLC was sitting on a DH+ to Controllogix, so I don’t think the Moxa was to blame for this occurence.

What is the model you are using? Always interested in methods of getting comms to 5/04’s.

This has happened again (admittedly after a recent Ignition upgrade although the Allen Bradley driver showed as running after the upgrade). This time all the tags are set for a defined scan rate (leased at 2 seconds, 10 minutes). If a new tag is added to the folder all the tags suddenly respond whereas before they all show red crosses. The wrapper file shows something regarding “[quote]requesthealthmonitor threw uncaught exception[/quote]”

What version of Ignition is this happening on?

The requesthealthmonitor thing is annoying and needs to be fixed, but it’s not the cause of the issues here.

Version 7.6.2.

Strange thing is when a folder that wasn’t responding had a new tag added (which caused all the tags in the folder to suddenly commuicate) the error message as described wasn’t added to the wrapper log anymore, the last ‘healthmonitor’ being just before the problem was cured.