ECWX/RX Success Fail Bits Not Working

[Schmu @ Maxam]

Well, I have 10 D2-260's in my plant with 2 talking to my VFD banks in the electrical room. I have written some safeties to kill the motors if communications drop to the individual control stations. Unfortunately, the Success and Error bits are not flagging even though communications are occuring. If I drop to program mode and then back to run, the bits function for a few seconds then stop. I have gone through all the memory addresses. The contacts are not overlapping, the workspaces are not overlapping and I am running out of ideas. Does anyone have any light to shed on this? Thanks!

[franji1]

Could it be they are only on for one PLC scan?  If you are "polling as fast as possible" (i.e. driven by ST1 "always ON") that will be true.  DirectSOFT status display sometimes will catch a bit that's on for one ladder scan, but even if it is, the next read occurs so fast, it may just flash for a very brief time.

I like to use a differential contact driving INC V instructions for each of my "success" and "error" bits so I can monitor their status numerically.  What's also good about that, is you can kind of get an idea of the data rates by how much those INC V locations increase in one second.

Code: [Select]

   C100
    _
-]_| [----------------------[INC V2100]

   C101
    _
-]_| [----------------------[INC V2101]
where C100 is one of your unique "success" bits and C101 is one of your unique "error" bits, incrementing V2100 and V2101 on every success and error.

[Schmu @ Maxam]

I actually have them powered by SP1, but they are attached to counters. So while I do not see them, the counter should.When I go to Program Mode, then back to Run, the coutners work and I can visibly see the bits changing (Success) but then it all stops (communications continue though). Counters pasted below.

#BEGIN COMMENT
"Counter to CS02. If had failed, counts will automatically reset the shut down."
#END
STR C12
STRPD C60
ORND C60
CNT CT4 K30


#BEGIN COMMENT
"Counter to CS02. If fail, shut down equipment."
#END
STR C13
STRPD C60
ORND C60
CNT CT5 K8

[franji1]

Are your counters immediately below the ECRX/ECWX instructions or immediately above or???

Also, are you doing any of this within a Stage or Subroutine?

[Schmu @ Maxam]

All the WX, RX's are in a single rung above the logic. The resets to the counters are leading and trailing edge contacts based off of a minute time. No stage or sub.

[franji1]

C12 and C13 are unique to THAT IBOX (no other IBoxes or other rungs), along with the workspace V register?  XRef view is best for determining this - don't rely on "find" (e.g. you could have a RANGEd instruction).

[plcnut]

Here is a great example program for drive communications that was posted by Bernie, you may find it helpful: http://forum.automationdirect.com/showpost.php?p=44628&postcount=8

[Schmu @ Maxam]

That's pretty neat for MODBUS. It beats the interlock crap I have now. But this problem is about the ECOM ECWX and ECRX with the success and error bits. I need the bits to work. I really can't rebuild the enire program right now, so I need to fix what I have. Thanks though! Any other ideas?

[Greg]

Are you using RX/WX at the same time you are using ECRX/ECWX?

[Schmu @ Maxam]

Yes, MRX, MWX, ECRX, ECMX.

[Schmu @ Maxam]

Any other ideas as to how ECWX commands are properly executing without the bits working? I never have easy problems, it seems. Thanks for trying, all!

[Greg]

Something has to be interfering with the bits, especially if the communications started by the ECRX/ECWX is working. It is not possible for the communication to be working and the bits to not get set ON.

Also, if you have MRX/MWX, these instructions are not interlocked with the IBox instructions ECRX/ECWX.

Barring any HMIs, PIDs or an ERM module overwriting your Success and Error bits, you could try testing this simply by putting an END at the top of your program and then putting only the ECRX/ECWX IBoxes above that END. This way the only code executing is the ECRX/ECWX instructions and the rest of the ladder is not running.

[franji1]

Note that MRX/MWX have nothing to do with ECOM modules - they are only valid with the local "Port 2" serial port on a 260, so they should have absolutely no affect.

You might want to make sure you are not doing anything with V40600 or any LDA O40600 (this is C0-C17 as a WORD) (e.g. RX or pointers or )

[Schmu @ Maxam]

It turns out the workspace addresses I was using after V650 were the problem. The software did not show any overlaps on those addresses, but when I moved them, the bits started working again. I see strange things like this every now and then. Thanks for the help everyone!