Strange fault on SLC 5/05 system.

I have been getting a fault on a SLC system that I do not know how to fix. The error is "a rack data error occured in slot 6" I am not sure what the problem is. Anyone dealt with this processor fault before?

The set up:
SLC500 "P2" power supply
10 slot rack
SLC 5/05 processor
slot 1 IA16
slot 2 IA16
slot 3 OW16
slot 4 OW16
slot 5 NO4V
slot 6 NO4V


Thanks in advance!

Never seen this fault, but some common-sense reasoning makes me beleive that the data stream between the module in slot 6 and the CPU sometimes comes invalid (there must be some kind of checksum mechanism involved).

Possible causes: faulty NO4 module, intermittent open in the backplane connector, intermittent backplane PCB trace.

Can you move the module to slot 7 and re-configure the PLC accordingly? Replacing the module and the rack would naturally follow if this does not help...

Well,
The system just went into service. The processor, rack, and digital I/O cards are used. The analog cards and the power supply are new.

I pretty much thought the same as you. My first "swap" is going to be the rack. I have a brand new 10 slot rack going in, as well as a swap of slot 5 and 6 NO4V's tonight during some scheduled downtime.

I'm hoping that if the problem does not go away with the rack swap, maybe it will follow the card...

I hunted the AB website/manuals for any info on this fault and I really can't find a description or corrective action.

The SLC-500 backplane is ferociously jealous of it's data integrity. There's an ASIC chip there whose whole job is to check the operation and identity of each module every single program scan.

The Rack Data Error (code xx50) is one of the toughest to troubleshoot. Usually it shows the correct slot number where the SLC backplane chip has a data error, either something out-of-range or the checksum failing.

If changing the rack doesn't help, you definitely have a noise problem. It might not really be in Slot 6 if the noise is getting into the empty slot circuit traces! Check noise suppression on the OW16's output circuits, and double-check shields on wiring connected to the NO4V for ground loops.

The P2 power supply is within about 110 mA of it's 24V supply limit. If the N04V are being powered by the backplane (there's a switch on the module PC board), you might try a separate analog circuit power supply.

Thanks, Ken

The empty slots have slot fillers in them. The NO4V's are set to external power and are powered by a SOLA 24-2.5-100 power supply that also supplies power to an N-TRON 4 port ethernet switch and a PanelviewPlus 700.

Update...

Swapped rack- problem persisted at same rate

Swapped slot 5 and 6 NO4V's (5 to 6 and 6 to 5)
Swapped slot 4 OW16 with new (was old used series A, planned to swap anyway)
Checked analog shields- all grounded and no loops
Nothing out of the ordinary close to the rack.

Still have problem, but has slowed from 3-4 times a day to 1-2 times per week.

I haven't been able to get the slot# since the slot 5 and 6 swap because, as seen in another post, I want to display the code on the Panelview. Time does not permit getting a laptop on it. Apparently the firmware in the SLC 5/05 does not support "last major error", at least it's not in the same S2 (structured) location as other processors. I haven't checked the actual S location (S:55 or whatever it is) address.

Surge Suppression: Currently none, the OW16's are only driving pushbutton pilot lights and tube base relays. So, I should say not yet anyway....



Any other Ideas?

Off the wall suggestion. From memory the only SLC systems that have ever given me this kind of grief were mounted in cabinets with non-metallic gear plates.

Even though all the SLC parts were grounded correctly to an earth terminal...we never got rid of the problem until we replaced the fibre gear plate with a metallic one.

The other clue is that the efforts you have made HAVE reduced the problem...which strongly indicate a noise problem somewhere.

Are there any other potential noise source in the facility? Anything inductive, big DC motor brake coils, large contactors, RF welders, variable speed drives, etc?


Maybe time to get the oscilliscope out and have a poke around.

Must be noise.

I have seen something similar, where it was the last used slot in the rack the indicated "problems".
I think the noise can enter the rack in one of the unused slots, and then affects the last used slot.

I'd try a bigger rack power supply. Power supplies cause strange, unexplainable things to happen to microprocessor based stuff.

Re: Update...

93lt1 said:

Surge Suppression: Currently none, the OW16's are only driving pushbutton pilot lights and tube base relays. So, I should say not yet anyway....

Click to expand...

I had a similar problem once and could not get it to go away. Actually I've had it a few times and replacing the rack seemed to fix it, but this one time... I had to put some code in to record which digital outputs were on when the fault occured by storing the output image words into a group of integers and then looking for a bit that was common when each fault happened. After 3 faults I was able to narrow it down to something like three devices out of several dozen. One of them was a faulty coil.

I searched for a possible solution and found this older topic that seems right on track. I have a SLC 5/04 with a P2 power supply, 13 slot rack with 1 free slot. I have a NO4V analog I/O being fed with an external AB power supply. I get a processor fault in rack 12 (the last rack slot and where my NO4V is located). I check for ground loops and found none.

The analog outputs goto 2 Rexroth Analog amplifier cards that power proportional hydro valves. This is my 1st dealings with these Analog I/O's. Any suggestions would be appreciated.

Did you add this module to your I/O Configuration