AB Micro850 analog output card issue

Hello,

We are using 80 micro850 controllers (2080-LC50-48AWB) to operate irrigation booms in our nursery. We are using an analog output card (0-10v) to control a DC drive board which powers a 90VDC motor for travel. We have a couple Micro 850's that stop moving and will not continue without a power cycle. On further testing, the value going to the analog output card (2080-OF2) increases, but the voltage across output 0 on the card remains at 0V. When the controller is powered down and back up, voltage is again present on the output card. This same process happens repeatedly on a couple controllers (all 80 running the same logic).

This issue seems to be more prevalent in Firmware version 12. A firmware downgrade to version 11 usually corrects the problem. However, we have a couple devices that do not respond even with a FW version downgrade.

We have tried replacing he analog output card - no difference. A new PLC did fix the issue, but I'm hopeful not to have to replace too many.

Has anyone experienced this issue before?

Many thanks

I have a few hundred of the OF2's installed and working and never an issue with any, I use them on LC50-24QBB's and QWB's... I have my IF2's in slot one and OF2's in slot two, have you tried moving your OF2 to a different slot on the failed PLC? How long were they installed before they started acting up?

On further testing, the value going to the analog output card (2080-OF2) increases, but the voltage across output 0 on the card remains at 0V.

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Can you reword this? You mean you check power on the card and its at 0 until you reboot the PLC then it goes up as expected correct?

If yes when the PLC 'should' be calling for output voltage what is happening in the program? is your output showing voltage but your meter is still 0?

By the way, I have used V12 on more than 50% of them so I dont think thats the issue

In our configuration we have :
Slot 1 - RTC
Slot 2 - IF2
Slot 3 - OF2
Slot 4 - HSC

No, I haven't tried moving OF2 to a different slot, but we could certainly try that. The time between installation and "acting up" has varied. Sometimes a couple months - sometimes within a few days of installation.

When I say

On further testing, the value going to the analog output card (2080-OF2) increases, but the voltage across output 0 on the card remains at 0V.

Click to expand...

I go online with the Micro850 using Connected Components Workbench (CCW). From CCW I can watch as the controller starts to "drive". The scaled value going to the output card (0 - 10V = 0 - 65,535) increases as the drive speed ramps up. A meter on the output card (at the same time) shows that as the value is increasing, there is no output voltage. After a power cycle, the same process occurs, only this time as the scaled value increases, voltage is again present and we're back in business.

All other cards work as intended, just the OF2 stops? Thats one thing I would check when it happens, is the HSC/IF2 still working and are you getting your values in and out... just wonder if 'all' I/O is somehow disabled until you reset power then they are all active again

Thank you. I think the others still work as intended, but I'll check next time it happens.

I've also tried using a module info function block, and no error is shown when OF2 acts up. I also tried a plugin reset function block, and OF2 resets, but a reset doesn't restore voltage like a power cycle does.

I'll check the other cards next time it happens - thank you!

So if you ever figure it out please come back and let us know.

And welcome to PLC Talk :site:

operate irrigation booms in our nursery

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Also how about moisture... if there a lot? Just thinking about the physical connection but I dont think that would get better with the power being cycled

Thank you!

I think we're good on moisture. The Panel is sealed (Fiberglass panel with rubber seals all around).

I'll keep in touch. Enjoy your weekend

I'd be talking with Rockwell. The red flag for me is the fact that changing from FW 12 back to 11 corrects the problem. I would also go look up what changed between 11 and 12 and see if anything stands out as possibly related. You may have stumbled across a problem with either the processor or module.

Firejo said:

I'd be talking with Rockwell. The red flag for me is the fact that changing from FW 12 back to 11 corrects the problem.

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sjacobjf said:

A firmware downgrade to version 11 usually corrects the problem

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Obviously Firejo knows more about the inner workings of these parts than I do but I think it maybe by chance that it 'usually' corrects the problem. All of the ones I have bought have come with V10 or V12 pre loaded have you also tried V10 firmware? I loaded 18 yesterday with V12 and a OF2 in the second slot and no issues, now once I load the program they are gone and I never see them again unless there is an issue but I have not heard of any.

Definitely a conversation with Rockwell is in the cards if I had 80 CPU's at one site, thats a lot of money.

Firejo said:

You may have stumbled across a problem with either the processor or module.

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Thats what I thought and way I said I never had an issue with the hundreds I have working but I only have QBB and QWB, not the AC version

Thank you Firejo and geniusintraining. Your thoughts are helpful.

I've been in touch with Rockwell support before (their free package - maybe that was the problem), and seemed to get the standard questions (check the power/ground, try a different firmware version, etc). Overall, I didn't find them real helpful, but I'll try again.

I appreciate your support - thank you.

2/24/2021 2085-OF4 module stops working after disconnecting wire
Answer:
Module DAC detects hardware errors like broken wire or high load resistance associated with the channel x, and the corresponding channel is locked (disabled) until user clears the error.
For further information refer to Micro800 Discrete and Analog Expansion I/0 User Manual Publication 2080-UM003.
CEx are written during run mode to clear any □AC hardware error bits and re-enable the error-disabled channel
X.
• Bit 8 is CEO
• Bit 9 is CE1
• Bit 10 is CE2
• Bit 11 is CE3
A value of 3848 will reset all 4 channels.
A value of 2056 will reset channel 3 (CE3).

tim_phillips said:

and the corresponding channel is locked (disabled) until user clears the error.

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Hi Tim,

Thanks for the information but the way I take the above is that it should start working again, without a power cycle once it comes back into range but I think sjacobjf is not resetting until power is cycled

But it is another thing to look at... wonder if you can write a min/max to keep it from error/locking out?

Hi Tim,

Thanks for your post, and the reference to Micro800 Discrete and Analog Expansion I/0 User Manual Publication 2080-UM003. In looking at the documentation there, they say that the status block for OF4 will produce a value in the "Ex" field of the function block. We've tried looking there and have (so far) not seen any errors when output drops out. We've also tried the "reset function block", and resetting the card doesn't bring the output voltage back.

Maybe though, as you quote above, writing the right value would reset the channels and do the trick.

Many thanks!

This is an addition to an "old" post, but we have an update on this. As I mentioned above, we were in touch with Rockwell. After some back-and-forth, they recommended that we try putting MOV's on PLC outputs to "clamp-to-ground" on any voltage spikes. Our outputs are connected to 24vac solenoid valves. I think we went with 40v limiting MOV's - anyways - this has worked for us. We installed these on any controllers that were having the issues of "no output" on 2080-OF2, and this corrected the problem. It appears from our conversations with Rockwell, that perhaps the inputs on the PLC's are internally protected from spiking, but not the outputs. A spike to the output on the PLC can temporarily knock out 2080-OF2 - which is only corrected by a power cycle. Anyways - thank you all for your help, and I thought you might appreciate the update.

Best regards!