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_NeveRMinD_

CP1H analog input problem

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Hello there, I'm using the first built in analog input on a CP1H model. It's set as a 4-20mA signal. The input itself is used to measure the water level of some well. My problem is that the analog input value after AD conversion oscillates (roughly from 800 to 1000, as an example), so the result scaling differs in +/- 2cm from the actual value. I'm using the 12000 resolution, and in my opinion the wiring is good. The same mA signal is connected to an another device that shows the water level, and the value on it is stable. So, can anyone help me with this issue?

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Have you set the Analog Input for "Averaging" in the PLC setup? Don't forget to power cycle the PLC after making this change.

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I've checked that check box, but it made no difference. What is that power cycle you're mentioning?

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Whenever you make changes to OMRON PLC settings they must first be transferred to the PLC. "Settings", "Options", "Transfer to PLC". In order for these changes to take effect power to the PLC must cycled [Turn OFF then ON]. Whoa! The same 4-20mA signal is connected to two places. PLC and another device. Not good practice IMHO.

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I made some value averaging in the program and it worked fine, but I would really like to make this built-in averaging to work. So I'll try your advice. As for the signal multiplication, it's a technique used a lot in the industry and works very well, never had any problems with it.

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Have you tried disconnecting the analog signal from "another device" and connect ONLY to the PLC?

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After restarting the PLC the averaging started working. Didn't know you had to "power cycle" when you make some settings changes, thought that downloading them was enough... Thank you for you help BITS N BYTES!

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