SLC Crashes!

lendyck

Member
lendyck
Join Date
Feb 2006
Location
Cambridge, Ontario
Posts
59
I've been working with an SLC 5/04 that likes to crash. It happened a total of three times while I was making online edits. It comes up saying that one possible cause is a low battery. When it happens all the memory is wiped.

Also, after the AC power has been removed for a while, the memory is lost.

There is no battery warning as well as the voltage on the battery is good.

Has anyone experienced this?

Thanks.

Len
 
You have a battery in the CPU. Then it is even more strange that the program is lost. In addition to the battery there is a capacitor that can keep the program for a relatively long time, 1 hour or so.

How long did you remove the power in order to provoke the problem ?

Guesses:
Defective power supply in the rack.
Defective capacitor.
Noise.
Ground connection not sufficient.
Shorting the supply terminals to the power supply (not sure, but I vaguely remember someone stating that this can cause problems).
 
May be 2 issues here. One a bad battery. The other, issues with changes your trying to make. Does it happen every time now? Are you always trying to make the same edit? Or, can it be any edits anywhere in the program?
George
 
The project I'm finishing right now has the a similar problem with 5/04s.

H/W Brand new 5/04s, I have 3 of them on the shelf, I've used two of them and they both behave the same. (2) racks with some local I/O, (2) SDN cards, (1) SN card, and a Escort RFID scanner.

S/W is RSLinx 2.50, RSLogix 7.1.

The instant I begin an online edit, I'll get a major fault (001F IIRC) and it dumps its memory completely. The fault code is not ducumented so a call to RA and they tell me that the memory image is goofed up and to save the program as a SLC format and reload it. It fixes it for a while and then it happens again, a total of 3-4 times during a day of online edits.

Without RA offering a fix there isn't much I can do but idle everything while I make online edits. I just loaded up RSLinx 2.51 and will see if that changes anything.
 
lendyck said:
jstolaruk...exactly! I've done lots of work on a 5/05, and it has never done this. Let me know how RSLinx 2.51 goes. I'm running version 2.43.

Len
Click to expand...

Len, I'm headed out of town Monday morning and won't get back to a 5/04 until the end of next week. I will update when I get back. -Jeff
 
There is a known situation where a processor may looks like it lost his memory: Noise.



At every scan, the processor is calculating the memory checksum and compare it to the last "Post Edit" checksum. If those two values are not the same, the processor changes a few bits and faults. Those few bits are the ones that tell the programming software that the processor memory is empty. Even though its memory is not empty, it forces you to download an uncorrupted program. This is OK since the processor cannot tell which bit(s) has changed in the memory space.



There are 3 ways that noise can reach memory:

1- Backplane: Insure that you have a ground wire on your chassis. Respect the manufacturer recommendations on grounds.

2- Power Supply: There are many small AC line filters that you can add on your supply.

3- Communication Ports: a communication isolator can be add



I have encountered this situation 4 times. 3 where due to incorrect grounding practices and one was due to noise coming through the serial port. I always use an AC filter on PLCs
 
I can't speak in Len's case but here is the interior of the panel that has the 5/04 that faults occasionally only when starting an online edit (if I get past that first edit, I'm good for a while). I used galvanized back plates instead of painted to insure good chassis grounding because there is (4) servos, A VFD, and a soft start, all good noise generators. There is a nice big grounding strap connecting the two sides.

That would be something new in my book to find out pushing the edit key in RSLogix trips an insufficient ground problem causing the memory to dump, but strange things have happened before.

gallery_7691_21_127715.jpg


gallery_7691_21_69772.jpg


med_gallery_7691_21_91951.jpg
 
Yes, I had previously tried closing absolutely everything else running not necessary that I could find to see if the problem changed or went away. It didn't appear to make a difference.

PS: also it didn't seem to make a difference if only the bare minimum components were powered up in the panel too, ie the high voltage side disconnected and only the SLC powered up.
 
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