Automation Directs PLC's

Has any one had a E504 Error on a D0-06AR PLC with a thermocouple card?

David

E504 - BAD REF/VAL - An invalid value or reference number was entered with an instruction

Sounds to me like an error in the program. I doubt it has anything to do with the fact that there's a thermocouple card installed.




-Eric

E504 - Bad Ref/val

Eric
I have about 96 lines of Logic. When I get these PLC's back they have over 6800. They have an illegal rung on line 6800. Automation Direct says it is either a transient or too small of a transformer. We use a 500va transforme and we have hooked it up to a 50 va and we can't make it happen. Would you care to see the program?

"Eric
I have about 96 lines of Logic. When I get these PLC's back they have over 6800."

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I'm confused??

elevmike said:

I'm confused??

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I'm not. Seen it lots of times.

You have some sort of electrical event occurring. Lightning strikes are the biggest cause I've had. It doesn't have to be a direct strike, the noise induced can cause this. I've also had main-line transformers blow up and cause it, and once a 480V 400A line went to ground under ground... That one was a mess.

In short you have an electrical noise problem. If you have anything connected to port 1 or 2 check there first. If not get some clean power to the PLC.

As a note; I'm in the process of changing all of our control panels to 24VDC powered PLCs and racks. To date I have not had this issue on a single PLC powered by a dedicated 24V power supply.

Also if you talk to AD tech support again tell them Mark Gentry from Samuel Jackson gave you this explanation. I've never successfully convinced them of this problem...

Marksji

We are running our power through a Powerline Filter. Shouldn't that keep the power clean? Why do you think the 24vdc changes things?

dyearous said:

We are running our power through a Powerline Filter. Shouldn't that keep the power clean?

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One would think so, but my experience tells me otherwise

dyearous said:

Why do you think the 24vdc changes things?

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I don't have a real good answer for you. Prior to trying the 24vdc route I tried all sorts of things to clean up my power I'm glad I finally found a solution even if I never understood the problem.

My guess is that the internal power supply in the PLC isn't really all that great; it probably puts out pretty dirty power compared to a typical industrial power supply
It could also be that if I give the PLC 24vdc it has to do a DC-DC conversion to get the voltage levels it needs (3v? 5v? etc). Maybe going through two conversions makes a difference... Of course I assume (I know, bad thing to do) that even on the AC powered PLCs that inside there is a 24vdc power supply and the same DC-DC conversion...

This is one I finally listed under who the heck knows, but I'm glad I have a solution. I've got several 250 and 250-1 CPUs on my desk right now that have come back from customers; thankfully I don't have any 06s laying around anymore. I got all those systems changed over.

One thing I did notice is the price for a 24vdc powered PLC is HIGHER than the price for the same PLC with AC power. Doesn't make much sense to me if they're removing a 24vdc power supply to get the DC model...

Mark, I would give the same answer. Dirty power. It isn't the running power that is the problem usually with this sort of thing. It is the startup surge that usually causes the problem.

500VA may be overkill for the running power, but severly insufficient for the startup surge current. This causes the heavy power drains to really start pulling and the voltage to dip and then spike when the heavy load gets powered up.

I have trouble convincing people of this, but it does happen and when people start talking about memory loss or "extra" rungs it is usually the culprit.

Makes enough sense to me. Most of the problems we've had with this are from overseas customers, mostly in Africa. I can't imagine the power grid being up to snuff in any of those locations. I'm sure starting and stopping several hundred horespower can cause some very nast power spikes when the grid isn't up to it.

If it was the transformer? Icky 812

If it was the transformer, hooking the system up to a 50 va transformer and cycling the power turn on and off you should be able to recreate the problem! Which we have done and can not!

You did not touch the 24vdc idea. What do you say to that.
Icky812 Call me 800-621-2589
or email [email protected]

dyearous said:

If it was the transformer, hooking the system up to a 50 va transformer and cycling the power turn on and off you should be able to recreate the problem! Which we have done and can not!

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Did you have the same loads connected or just the PLC?

Marksji is correct, it is related to power problems of one sort or another. I didn't mean that it had to be the control transformer, merely that it could be.

Changing to a 24V DC model may certainly help, but it most likely won't correct the original problem, it will only mask it. The original problem will still probably remain and possibly damage other components over time.

I am 99.9% sure that this is being caused by power problems.

My advice would be to get a power analyzer or at least a scope and see if you can find anything.

You could also get an on-line UPS and feed only your PLC with the UPS. Note that it would have to be an on-line UPS to really solve your problem.

Possible Design flaw

marksji and icky812
We have looked into the flash chip that holds the program. This is the email from the Application Engineer for the chip.

----- Original Message ----- From: Foster, Trent
To: Bill Wynn
Sent: Friday, April 22, 2005 2:30 PM
Subject: Renesas Microprocessor



Bill,

Per our conversation, the WRITE pin on the micro is active low and should have a pull-up resistor on the line to ensure a known state for the purposes of programming the FLASH. This is especially important for transitions between know good states as extra and/or erroneous data could be written into the FLASH space. Some of the Renesas devices have programmable internal pull-up resistors however they do not always limit the current flow sufficiently to ensure absolute state transitions and therefore it is good practice to use a hard pull-up external to the device. The internal programmable pull-up resistors are better suited as terminations for pins with no external connection.

Let me know if you need further info.

Thanks,

Trent Foster
Field Applications Engineer
Avnet Design Services
2855 E. Cottonwood Pkwy St. 220
Salt Lake City, UT 84121
801-365-3800



This is why cleaning up the power on the 120 PLC's won't help. icky812 can you contact Koyo to confirm the pull up resistor? If it isn't there can it be put there like the manufacturer requires?

Have you tried cleaning up the power to see if it helps on any of the problem PLCs? You state that cleaning up the power on 120 PLCs (quite a few out there) won't help you, but I'm curious if that is based on what an engineer read from a spec sheet for a single chip or a trial in the real world.

I'm not trying to be harsh, but I know that in my case cleaning up the power solved the problem. Also I noticed that there are 3 "static ram" chips on the CPU. Which one holds the ladder?

Clean up Power

Marksji
1. We have added a Cutler Hammer Power line filter Part # APF120N05 between the Transformer and the PLC.
2. We have added TVS's across all coils.
As far as we have been told the Ladder is stored in the the Flash memory chip (IC15)and none is stored on the 3 "static ram" chips on the CPU. Those hold timer and counter information.

We have not had a failure since adding the TVS's, but that has only been in the last month. Too short a time span for me. We would like to know exactly why we have had these failures and how to recreate them.

Besides the ON-line UPS do you have any other suggestions to clean up the power?