ABB AC500, Modbus and Beijer hmi (Comms seem intermittent)

[arpus4KM]

Well, I'm working with this ABB plc project, and It's been a learning experience coming from Allen Bradley. The project can't be changed to an AB unit, even though it would be easier to service for my whole office.

Where I'm getting weird issues is with the HMI not having solid communications with the PLC.

It's communicating through Ethernet, Modbus TCP/IP. I've had the communications working fine more than once, but it seems intermittent. Sometimes on startup I won't get any kind of modbus comm error on the hmi, but tags and values don't update properly. I can disconnect the cable, see a modbus comm error show up, and plug back in and still nothing.

Other times it will work flawlessly, all buttons and feedback work. I can see analog in values and write to the registers. What might be going on with this? or is it just a weird communication problem with modbus and beijer or ac500 issues?

 

[arpus4KM]

Just putting this here in case it's ever searched.


The issue was that Modbus Comms were established, so I never got an error stating they were bad unless unplugged.

But ABB PLC have the option for %M area and %R Area. the tag base I had was using the %R area for modbus (persistant I believe). and It kept reverting back to %M area whenever the system would restart. so downloading the program after a restart would allow the tags to update like they should, but a power down would cause it to boot with the wrong settings.


This was fixed by using the "create boot project" option on download. This just seems to be a thing with ABB, I'm not proficient with them, but after making a boot project, rebooting the system kept the %R area setting for comms and it's been good since.