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Author Topic: Analog Output Counts  (Read 8272 times)

dustin.elliott

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Analog Output Counts
« on: June 11, 2019, 07:03:26 PM »
Hi,

I have a PID loop that running a +/-10 VDC analog output. The PID loop is set to scale the 0 to 100% to -32767 to 32767 (to match the range as shown on the system config page). The PID loop is working and I can see the counts change and the output change. However, the voltage on output isn't changing smoothly the way the counts are. From what I can tell during testing is the voltage output doesn't start changing until the counts are between approximately -5000 to 5000. This doesn't make sense per the info on the system config page. Am I missing something here?

Thanks,
Dustin

BobO

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Re: Analog Output Counts
« Reply #1 on: June 11, 2019, 08:45:31 PM »
No, it looks right to me.

If you disable the loop and drive WY0 directly, does the output do what you expect? What is WY0 driving? It is a high impedance voltage input, right?
"It has recently come to our attention that users spend 95% of their time using 5% of the available features. That might be relevant." -BobO

ADC Product Engineer

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Re: Analog Output Counts
« Reply #2 on: June 12, 2019, 09:59:31 AM »
No, it looks right to me.

If you disable the loop and drive WY0 directly, does the output do what you expect? What is WY0 driving? It is a high impedance voltage input, right?

I would agree, what is the impedance of the load?

dustin.elliott

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Re: Analog Output Counts
« Reply #3 on: June 12, 2019, 04:36:14 PM »
The impedance of the input is ~1 Mohm. It turns out the PLC is working properly and the motor drive it's connected to is the one responding oddly to the input. Thanks for the help.