Problem with a 1769-OF8C, CompactLogix

Elcan · Jun 24, 2010

Hi all,
I'm experiencing this weird situation. I have a 1769-OF8C Analog Outputs card, used with a CompactLogix, and RSLogix 5000. I set this card to send a 4-20 mA signal.
The problem is that I'm getting 12 mA all the time at the outputs, no matter the values I try to send.
Any idea about what I'm doing wrong?

Thank you!

rdrast · Jun 24, 2010

Somewhat WAG here, but if you open up the properties box on the analog module, and go to limits, do you have the limits set to appropriate values?

harryting · Jun 24, 2010

What's the output data echo (Input word 3-10) says? Have you wrote configuration data over yet? Are you seeing any faults?

More details, please.

Elcan · Jun 24, 2010

rdrast said:
Somewhat WAG here, but if you open up the properties box on the analog module, and go to limits, do you have the limits set to appropriate values?

Oops! Too much World Cup for me!

Andre.pimant · Apr 4, 2014

I have the same issue, how i can solve that. I has been tested the channel 0 with 500 ohms resistance but dont works. Always 12mA.
Somebody help me with configuration parameters. Thanx

Bit_Bucket_07 · Apr 4, 2014

rdrast said:
Somewhat WAG here, but if you open up the properties box on the analog module, and go to limits, do you have the limits set to appropriate values?

The first time I installed an Analog Output module in a ControlLogix system, I was surprised to find that the upper and lower limits both defaulted to zero. I would have expected 0 to 100% as the default configuration settings. Nope.

Ken Roach · Apr 4, 2014

You're right about the clamp values. Andre opened another new thread and we found that the "stuck at 12 mA" symptom lines up with "Raw/Proportional range and default 0/1 min/max values".

It's a common-enough issue that it's described in the RA Knowledgebase (TechConnect Required)

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/46010

Bit_Bucket_07 · Apr 4, 2014

Ken Roach said:
You're right about the clamp values. Andre opened another new thread and we found that the "stuck at 12 mA" symptom lines up with "Raw/Proportional range and default 0/1 min/max values".

It's a common-enough issue that it's described in the RA Knowledgebase (TechConnect Required)

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/46010

To be honest, I'd rather not even have this configuration option. I can set clamps in my program logic. This strikes me as a solution desperately searching for a non-existent problem.

shailesh_vb · Jan 14, 2017

Maybe problem is solved.
I was going through same problem. I changed Data format setting to "Scaled for PID" and set limits to "0..16383".

It solved and I got 4..20mA at outputs.

Regards,
Shailesh

daba · Jan 15, 2017

The infamous Limits tab on the configuration dialog....

I always make a point of that when teaching analog output configuration...

Changing the onboard scaling from default values does not change the limit (clamp) values.

But once you know, or have been trained to know, it's easy.

I disagree with Bit_Bucket_07 - configuration is the best place for this, as it a physical constraint opposed to a programmed constraint. What if a maintenance tech forced the output to 100%, the output mudule limit would still apply, which is as it should be.

Problem with a 1769-OF8C, CompactLogix

Elcan

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rdrast

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harryting

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Elcan

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Andre.pimant

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Bit_Bucket_07

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Ken Roach

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Bit_Bucket_07

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shailesh_vb

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daba

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