kcox1980

That's what I thought, but as I was going to put the instruction in, the thought occurred to me that it might accept the same tag for both.

The application in question is a length measurement. Individual roll lengths are stored in a REAL data type but at the end of each roll the length is added to a daily total which is stored as a DINT type. At the end of the shift the operators record the number stored in the Length_Total into the log book and that value is used to determine material usage. We have some discrepancies on our usage and I suspect we are losing some length data in this calculation. The ADD instruction looks like this; Source A: Length_Total  ~> DINT type Source B: Roll_Length ~> REAL type Dest: Length_Total ~> DINT   What happens to the numbers after the decimal in this calculation? Are they dropped off or rounded up/down?

Thanks for your help. I realize this was probably a basic question but my primary PLC background is with Mitsubishi systems. I've been on this job for about 3 months and at this point I am basically self-taught with AB while awaiting my training classes scheduled for later this year.

Probably should have mentioned this in the original post but the units are in feet and the setpoint is 100.4 per roll. So if I understand you correctly that means I am correct in assuming that I am losing that 0.4' (plus or minus natural error in the system) on every roll?

While I can't look at the internals of the HMI project, based on the behavior of the machine I believe that it is just setting the bit. The tape heads can be disabled either by an HMI button or a physical button near the head itself, however the only way to re-enable them currently is by an HMI button. Again, I can't confirm the behavior of the HMI disable buttons but the physical buttons are momentary I believe(I'll double check that, I was sure until I typed it out haha).

Is it possible to latch a bit directly from an HMI without an OTL instruction in the logic? The PLC platform is RSLogix5000 and we are running a version of PanelView though I'm not sure off the top of my head which version it is.  We have some automated tape heads on our line that can be disabled remotely while they change rolls but to re-enable it they have to walk all the way back to the HMI. I've been tasked with providing a remote enable function which I thought would be easy enough until I started looking at the logic and was unable to find the latch instruction.

Not really much to it. What I have in mind for the modification is just an XIC bit with an ONS for my remote enable button and an OTL to match the HMI command address. There are a total of 4 tape heads with identical logic FYI.

I was afraid of this. We do not currently have a developers license for modifying the HMI project, so if I were to add an OTL instruction to the PLC would it cause any kind of conflict?

Hey everyone, I'm new to the forums here. For a short introduction my initial training and first on the job experiences were with AB systems but not only was my job scope pretty limited(all I did was load a pre-made program into a newly built machine) but I has been several years since I've done even that. For the last 4 years my programming skills were developed on Mitsubishi systems, which were quite different. Now I have a new job as a Process Technician and one of my responsibilities is to develop my AB skills up to where I was at with Mitsubishi systems so that this new company can stop the current practice of having to outsource any PLC changes and troubleshooting to an integrator. I've spent some time on the phone with one of said integrators and that got me caught up a lot but I also have some training classes scheduled later this year.   So now that's out of the way, on to my question: We are having an intermittent issue where one of our extrusion feeders stops filling up for an unknown reason. I'm wondering if Logix 5000 has a feature where I can record a rung or even just a few tags so that if an event happens we can go back to that time stamp and see what the logic was doing at that time. For this particular issue I suspect a hardware problem but some confirmation that the logic is doing what it is supposed to would be nice.