1785 l30b/e

roxusa · Dec 31, 2018

I have a PLC5 that is faulting and I am unable to go on line when the controller run/fault light is red. This Processor has been in use for 25 years and had a
PC / HMI added a few years ago that has a Digi Switch between it (Eternet) to the DF1 Channel 0 on PLC. Started faulting last week and cycling power to PLC
will restore it (power stays on PC/HMI) and it will work sometimes for Hours.
I was hoping I could be on line to see what fault is, can I add a (U) S:0/1
as last rung to make sure it is not a math overflow.
Any Ideas,Thanks

BachPhi · Dec 31, 2018

most likely hardware problem. I would try to reseat the cards first.

roxusa · Dec 31, 2018

I reseated all the cards and swing arms Sunday and ran for 6 Hours fine. Turned control off but processor and PC/HMI stay powered. This morning PLC was faulted again. Wont run until Wednesday I will look int a new Processor but wish I could see fault description. Does this Processor save fault info.

roxusa · Dec 31, 2018

I also ordered a new battery even though this one looks good

Mickey · Dec 31, 2018

Bad power supplies can do this also.

FYI, PLC5's do not fault with a math overflow.

roxusa · Dec 31, 2018

Will Processor hold last fault I look at File S2(Processor Status)Errors tab, For a Old merge File and it had this message in S:12
You entered a negative preset or accumulated value in a timer instruction
I uploaded again today after resetting fault by cycling power with out a merge and it was still there under S:12 this time I cleared it and disconnected my laptop to plug the PC/HMI back in and it has been running several hours no fault. If it faults again I will upload and look again. I am reading the manual on Fault Routines.
Although my fault is a solid red on the PROC

OkiePC · Dec 31, 2018

roxusa said:
Will Processor hold last fault I look at File S2(Processor Status)Errors tab, For a Old merge File and it had this message in S:12
You entered a negative preset or accumulated value in a timer instruction
I uploaded again today after resetting fault by cycling power with out a merge and it was still there under S:12 this time I cleared it and disconnected my laptop to plug the PC/HMI back in and it has been running several hours no fault. If it faults again I will upload and look again. I am reading the manual on Fault Routines.
Although my fault is a solid red on the PROC

I think that the fault code is retained, but it has been too many years for me to be certain of that. I would add a tag pointing at the pertinent status registers to whatever HMI you have handy, then use it to generate alarms. If you want to get real fancy you could even copy the alarm text from the manual to the various states of the alarm word(s) so the HMI will literally RTFM for you based on the fault code.

If the fault is a negative preset, then you should add limit checks to any logic that can write to a timer preset, and make sure you are not directly accessing them with the HMI or other devices on the network.

roxusa · Dec 31, 2018

Thank You
I have been studying this Program The error listed said file-5 rung 22 for the fault location
but that rung only has an XIC bit to a OTE
However rung 21 has the math and a Timer that is set for load position (conveyor) and in it I see the possibility of it getting a negative number.
The HMI is PC based and I don't have any way of accessing it.
I will upload program again if it faults and see if it points me in the same directions and if so change some of the program so the timer PRE can't go negative
Thanks Again

OkiePC · Dec 31, 2018

roxusa said:
change some of the program so the timer PRE can't go negative
Thanks Again

I'd recommend this as a preemptive strike and a generally good practice for any calculated or HMI adjustable preset.

roxusa · Dec 31, 2018

I will need to find a way to be online with processor while it is running to see how they are shifting integers from HMI to conveyor, The DFI is going to Digi and then Ethernet to PC/HMI. I did ipconfig to find IP of Digi Module Can I expand this with a switch and use ethernet driver in Linx t0 see PLC.
Not sure what I would need for the 8 pin mini DIN DH+

roxusa · Jan 2, 2019

After clearing fault at PLC and leaving power on I found it faulted this morning
again. Attached is the program shows the fault at File-5 Rung 22 but I believe this means rung 21 as that is where a timer is.I did find a faulty Photo Eye I just fixed and will watch for fault again. Since this program has been running years I hate to have to edit for this problem and would like to be sure it is what I think. I found my old PCMK card and am looking for the cable so I can monitor online while PC/HMI is connected.
Looking at program it looks like valid data (B16:7/0) is set for 12-130, and looks to me if it is less than 50 the next part of that rung will subtract 50 and give me the negative number going into T15:12/PRE

Any suggestions, Thanks

jdbrandt · Jan 2, 2019

roxusa said:
I will need to find a way to be online with processor while it is running to see how they are shifting integers from HMI to conveyor, The DFI is going to Digi and then Ethernet to PC/HMI. I did ipconfig to find IP of Digi Module Can I expand this with a switch and use ethernet driver in Linx t0 see PLC.
Not sure what I would need for the 8 pin mini DIN DH+

You would need a 1770-KF2 box, and cable. eBay; about $40.00 last I looked.

roxusa · Jan 2, 2019

what cable do you use with the 1770-KF2 Box to PLC-5

1785 l30b/e

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