AB PLC analog input card 1771 IFE

diribarren

Member
Join Date
Jul 2002
Posts
5
We have a PLC5 with a new analog input card added to it---this PLC is on remote IO. There are two PLC's controlling this one area in our plant. Anyway the analog input card (1771 IFE) just locks up and quits reading our tank levels. To correct it ---or get them to start reading levels again the maintenance tech toggles power on the other remote rack! I can't find anything being sent from the remote rack that would step on the level data but I can't figure out what toggling power on the other racks does to this one analog card. Any ideas?? I read in a forum somewhere of a similar problem but can't find the article! HELP!! :)
 
analog card tip

Your analog card is improperly programmed in terms of reading back the
bits which tells you that the card is alive and well. You need to
carefully analyze the BTR's and BTW's and all the bits necessary to set up the card and read back the card's health. This problem is
not uncommon, I had to correct this type of problem
caused by other people's sloppy programming, on several ocassions.
I am not going to do your work for you, get the manual and start analyzing the bits and bytes.
 
As mentioned this is probably a problem in the logic not recognizing that the analog card needs to be reconfigured.

One thing I see every once in a while is people setting up continous BTR and BTW instructions. For the most part they are ok but when an error occurs these instructions must be reset and most people miss that part.

Find the BTR and the BTW instructions for this card. There are all sorts of "preset" ways to write the logic to get different types of operation. I am going to point you to the A-B user manual which shows the most common method of writing a BTR and a BTW. This method will do a read then a write then a read then a write.......and so on. The drawback is that it does more writes than is really necessary on input cards and more reads than outputs need. BUT, it works.

Take a look at this link and print out page 15-17 and compare it to what you have.

A-B Manuals Online - PLC5 Instruction Set Manual

Post again if you need more help. As was mentioned, we obviously cannot do your work for you, but we are more than happy to help point you in the right direction and help you out along the way.

OG
 
YEP---I have it setup like in the manual for a continous BTR then BTW---which I don't like but I want to make sure it works! This problem only happens intermittently and I can't get maintenance to document the errors etc. I can't sit and wait for it! I know I had heard of someone else having this weird problem but maybe not! THanks for all the advice! I will let you know as soon as I can isolate this problem!

SMILES!
 
I've heard that having two AB plc's controlling the same equipment will cause problems (unless they are setup as master/slave).
Could that have any effect on the problems he is having?



Russ
 
I guess I just let that slip through as someone who is not totally familiar with the terminology. I envisioned this as two chassis each with their own PLC5 and blue hose connecting them together. That blue hose is generally thought of as Remote I/O when it could be DH+.

Even if it is RIO, the PLC5 is in the same chassis as the analog card is the PLC where the block transfer instructions will be found. What could be happening here is that the other PLC5 is sending data to this PLC and overwriting the Control block.

diribarren take a look at those BTR/BTW instructions again. There is a parameter called "Control Block". If this is a "N" value such as N20:0 then it is possible that this data is being overwritten by the other PLC5. Go into the other PLC5 and search for MSG instructions. Then go into the Setup screens for the MSG instructions and look for ones that say "PLC-5 Typed Write. Reads are not important, just writes. Look at the section that says Target Device and below that should be a field that says Data Table Address.

Now take that address and add the "Size in elements" field. If for example the destination is N25:0 and the size in elements reads 500 then that write instruction is overwriting N25:0 through N25:499 in the other PLC-5. So if the Control Block I mentioned earlier were say N25:250 then we definitely have a conflict.

I still think the problem lies in the block transfer instructions as mentioned in a previous post. But hey, this could cause problems too and it is easy to do.

OG
 
While you're checking that "BTR/BTW control block over-write" that Operaghost wisely suggested, think about this one too. It's a very long shot but I've run into it before. Do you have an MMI on the system? If so, is it possibly writing into an incorrect location in your data files? Specifically, into areas associated with the BTR/BTW control blocks or possibly into the configuration data for the IFE card? The situation I ran into revolved around a typographical error on the part of the RSView programming guy. He was toggling the wrong address in the PLC and causing all sorts of intermittent mischief.

Good luck.
 
Even if it was on Remote I/O the PLC5 in the remote chassis still has control over all of it's on I/O including analog cards so I don't think that is an issue here.

I should mention as a follow up to my earlier post that if your Control block is an "N" file then be aware that the block transfer needs 5 words for each BTR or BTW. So if the Control Block is N20:0 that means it is using N20:0, N20:1, N20:2, N20:3, and N20:4. So if any one on a network, either another PLC, or an MMI as Ron suggests, is writing to any of these locations, problems will most definitely arise.

Make sure you let us know if/when any of these suggestions help solve the problem.

OG

p.s. I still think it's that Continuous setting that is messing things up. If a BTR/BTW is set to continuous and an error occurs, they cannot reset themselves! There I said it again, now I will shut up.
 
We had this problem also in the past.
This card is in a remote i/o adapter rack.
If your programming is Ok, check if the card is a 1771-IFE Series A.
If this is the case, replace it for a 1771-IFE Series C or higher.
Norman.
 
diribarren,

I am having a simular problem right now. The big difference in my problem and yours is my analog card card (1771-IFE, series A) is in the local rack. I have posted my problem here before. Try HERE . I havent updated the post in quite a while, but still am having problems, and am still trying to test, verify the block transfer excecution by looking at its status bits. I am lucky enough though that my company has a service contract with a local supplier, who is also helping us with the problem. I'd love to see what some of your test/results are.

Good luck.

Andrew
 
diribarren

I am a little confused on exactly where the IFE card is located and what does the second PLC have to do with this part of your system and which chassis is having its power cycled.

Describe your system in more detail, correcting what I have below.

I will assume you have two PLCs both configured for scan and managing their own I/O and linked via DH+.
I will call the PLC that scans the IFE module in question, PLC #1.

PLC#1 is in its local chassis; (PLC-5/??)
How many racks is the chassis configured for?
Is the IFE module in that same chassis?
If not, which chassis has the IFE module?
Which rack has the IFE module?
Which chassis is having its power cycled?
How, by what means, is the power being cycled?
When the IFE module stops functioning what status are the LEDs?

Roger
 
Had a problem today with an 1771-IAD 16 point input card which was located in a remote rack. It was showing no inputs. The ACTIVE light was out. Cycled power to the remote rack and the ACTIVE light came back on and the inputs came on, but then we noticed that there was an Analog input card 1771-IFE in the same rack, and when the power was cycled to the remote rack the run light on the front of the card started flashing and we were not getting any values back from card. Well technically I suppose we were, but the values were all zeros.

The logic in the PLC had a rung which preformed a BTW to card on 1st scan bit. Toggled first scan bit and RUN light went on solid.

About 5 or 10 minutes latter, we turned off power to remote rack to replace input card and again when we powered it back up the RUN light on the Analog Input card was flashing. This time instead of toggling the 1st scan bit, I cycled power to the PLC. When it restarted the RUN light again went on solid.

So in your case, the cycling of the power could have done the same thing. You did not say weather the Analog card was in a remote rack, but if it was, maybe it was ending up in a condition similar to the above. Possibley due to communication between the PLC and the remote I/O adapter?

Kim
 
Last edited:

Similar Topics

Hi all, I’m an electrician with limited knowledge of PLC circuits. Typically I will see simple 2/3/4 wire terminations for transmitters on...
Replies
26
Views
1,160
Hi all, I want to catch min piks of an analog signal when digital signal is on(pls see the attached oscillogram). My hardware is 5069-L306ER CPU...
Replies
3
Views
948
Hello I have a analog input signal that is bouncing a bit. The PLC card is a 1769-IF8 I changed the input card filter setting from 60hz to 50hz...
Replies
14
Views
4,747
Dear all I am using delta AH530 RS- 2 cpu with devicenet communication and now I am getting problem while configuration of AH6xa-05 which is...
Replies
0
Views
1,020
Hello everyone I got problem during practical. I am using delta plc model:DVP20EX00R2. Problem is that when i give 7v dc supply through bridge...
Replies
4
Views
2,378
Back
Top Bottom