S5-95U that loses FB's????

Heino Geerdens · Sep 1, 2006

Hello,

Does anyone ever had experience with an S5-95U that loses FB's when they shut it down and restart again?
I'm quit new to the company so i've never had a chance to see it myself. According to the responsible, every now and then when they restart the machine after power-off, some FB's seem to have disappeared, online-offline comparisation confirms this. After reloading them it runs without any problem.
Does anyone ever saw this phenomenon? My guess would be peaks on the power-supply, or bad ground (checked it and looks OK)...

Thx
HG

gregoryg · Sep 1, 2006

Is there an OP connected to this S5-95? I saw similar problems with S5's when they were connected to OP.

geniusintraining · Sep 1, 2006

Heino,

I would say that you need to see it for yourself...

Something just does not make sense to me...are they saving the program correctly?

also are you sure they said FB and not OB's? some OB can be in the PC and not the PLC

gregoryg is better then I so listen to him.

But I still can't see that happening, I have a lot of S5's and a few 95's but I have not had that problem

Please up date us if you ever find out the issue

gregoryg · Sep 1, 2006

This is what I should say first.
Check your backup battery! If it's faulty then after power failure CPU loads program from EPROM module and if there is an older program version stored, you will loose all changes you're making. If you are loading blocks to CPU they are stored in RAM not in the EPROM.

Clay B. · Sep 1, 2006

I have seen something similar. Eurotherm used to make a fiber optic link system that would lose its program or the program would be corrupted on power down. After some research I found the problem was a capasistor that was to small. Basically what was happening was the program could not store itself before that power level on the cap dropped out. What you are seeing could be soemthing along these lines...IE a weak battery The battery would be the first place I would check.

JesperMP · Sep 2, 2006

Are you sure that it is FBs that dissappear mysteriously ?
I could imagine if some DBs would be lost. DBs can be created programmatically. Normally all blocks exist on the EPROM including most DBs. But you can also create DBs via the program. That could explain if the DBs are lost at a powercycle if the backup battery is empty.

Heino Geerdens · Sep 4, 2006

Hey guys,

Gregoryg, yep there's a display it's a ESA electronica type VT-420.
We have similar machines with identical configuration, and I believe that the CPU has been changed, I'm hoping the battery has been checked.
I'm trying to get more information ...
Thx

Heino Geerdens · Sep 4, 2006

Ok, here's an update on the info
- No FB's or DB's are lost, all DB's just DB 1 will remain.
- The CPU is replaced, the battery too but will check it to be safe.
Haven't seen the program so can't say if DB's are created by the program or not. But if DB's are made by the program it shouldn't be a problem to restart it, in our case, the DB's have to be loaded by with a PG.
If the battery would be dead, this would appear after every power-loss but it only happens one in a while!

HG

JesperMP · Sep 4, 2006

Hello Heino.
Your first and last posts contradict each other.
Are some FBs "lost" or not ?

Anyway, you should also check what gregoryg´s suggest about differences in RAM and EPROM.

kenschunk · Sep 4, 2006

DB1 <should> be recreated by the CPU when it performs a cold reset. My first question would be memory module - is there one in the PLC, and what does the PLC do if you power cycle it without the memory module in place? It sounds to me like the system is restoring from the memory module, and the memory module doesn't have the DB's in it.

As far as the battery goes, if it's just <mostly> dead it might still have enough capacity to backup the memory for a short period of time. I haven't worked with an S5 for a few years, but I seem to remember needing to leave the battery out, and power off, for several long minutes to get one to reset. The internal capacitance would be enough to ride through a short power outage.

Heino Geerdens · Sep 4, 2006

JesperMP said:
Hello Heino.
Your first and last posts contradict each other.
Are some FBs "lost" or not ?

Anyway, you should also check what gregoryg´s suggest about differences in RAM and EPROM.

No FB's are lost only DB's.

kenschunk said:
DB1 <should> be recreated by the CPU when it performs a cold reset. My first question would be memory module - is there one in the PLC, and what does the PLC do if you power cycle it without the memory module in place? It sounds to me like the system is restoring from the memory module, and the memory module doesn't have the DB's in it.

I've just checked it, no memory module is in place.

Just talked to the maintenance guy, according to him power-off sometimes is used as a reset-function, this means that it will only be down for a short while. This could explane why sometimes there's no problem.
To be sure I'll start with checking the battery, if that's Ok I'll come back.
Thx so far!

OK, just checked it; Dated 07/2006 I've got 3.68Vdc. Anyone got an idea?

JesperMP · Sep 4, 2006

Hello Heino.

There can be two explanations to the missing DBs (that I know of).

1. The DBs are created dynamically in the program rather they are fixed on the EPROM.
Some programming error causes the program bit that creates the DBs to fail. There is little you can do about it without expert knowledge about the program.
However, on most 'normal' programs this method is not used, so it is unlikely that it is the cause.

2. The DBs are fixed, meaning they must be on the EPROM.
The reason that they disappear upon reloading of the EPROM is that the programmer forgot to put them on EPROM.
You can solve that by making a new EPROM with all the necessary blocks.

Heino Geerdens · Sep 4, 2006

Hi Jesper,

I'm not that familiar with Siemens certainly not with S5, so i've got some questions;
- are DB's always fixed in S5 or is this a setting that could be changed
- With the EPROM, do you mean the memory module (isn't used) or does it have an additional EPROM? If so, I guess you need a burner to program it.
I think i need to learn much about S5!
Thx!

JesperMP · Sep 4, 2006

Hello again Heino

- are DB's always fixed in S5 or is this a setting that could be changed

Normally they are fixed. But some programmers 'cleverly' create the DBs dynamically. But this is only used in a small fraction of the programs, and then only on more advanced projects.

- With the EPROM, do you mean the memory module (isn't used) or does it have an additional EPROM?

If there is an EPROM installed you cant miss it. It has a large orange plastic retainer that potrudes out from the PLC.

But as you say now that there is no EPROM at all, then I am very confused as to what is going on.
I assumed that the program was loaded from the EPROM and for some reason the DBs where not on the EPROM. And if the battery is also OK, then the explanation must be something else.
Could it even be that the DBs are deleted dynamically ?
Or that some external factor deletes the DBs ?

gregoryg · Sep 4, 2006

How is that display connected to CPU? Via PG port or for ex. Sinec-L2 interface?

S5-95U that loses FB's????

Heino Geerdens

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