PV900 - SLC5/04 help needed

[CRMCC]

Iam having a problem tracking down a fault on a machine. The problem is with a separator controlled by a SLC500 (1747 L542B 5/04), this has a PV900 (2711-K9A5 Mono Key DH485) for data input, monitoring and alarms. A while ago a contractor changed the software to enable some of the ancilliary equipment to be controlled manually from the PV, but only when the machine was stopped. His first attempt allowed a waste pump to be run without any fluid inside, and due to the type of pump the internals would wear out very quickly. He then reprogrammed the machine to not allow the pump to be run in manual at all, but other faults are still present. The major fault that we get is if the bottom probe on the waste tank fails, and then the top probe of the waste tank is triggered, the machine stops(this is the correct thing and was in the original program) but the waste pump then shows on the PV that it is running even though it is stopped. The first time this happened it took a long time to find the fault as we were investigating the pump as it had the wrong status, now we know it is a problem with the bottom probe we can remedy the fault easily. However it would be be better to get rid of the incorrect states on the PV and posibbly add a meaningfull alarm message when this happens. Any help would be greatly appreciated.

Item Description Tag Tag address
pump solids pump m320_01 N31:31
LLP solids tank probe min Is_01_912_015 N31:50/1
HLP solids tank probe High Is_01_912_016 N31:50/2

 

[Ken Roach]

Welcome to the Forum !

Thanks for posting that screencapture and ZIP file.

I don't have the editing software handy but I think I see what the original programmer did: he used a Multi-State Indicator to try to indicate just three states (Running, Stopped, Failed).

But because the integer Word he used for the indicated value is used for more than three states, he tried to account for word values that included those three states as well as other bit values in the word.

If given the choice, I would find an unused word in data file N31 and dedicate it to this one indicator, then add (or fix) logic to set just one bit for each state. That would be the most clear method both in the SLC-500 code and in the PanelView.

Another method would be to use a Bit Array in PanelBuilder32 to narrow down the value to specific bits that indicate Running, Stopped, and Failed. This is only going to work if the bits are adjacent.