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Gnex

1769-OF4CI - Output always @12mA

5 posts in this topic

Hi there, is somebody experience whereby the output of the 1769-OF4Ci is not responding on the value entered?. 

Setting: 4-20mA

Res: 0- 32767 - PID set

whatever value I key in the output current remained. 

please help.

Ganie

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Do you have a load across the terminals within the proper impedance range?

Are you measuring the output with a meter?

If so, try forcing the output to a different value.

Does it respond? If not, try using a different output channel on that same module. If that works, the previous channel is faulty.

If forcing the output did work on the original channel, insure that any instructions you're using to control that output are being scanned.

Are the values for that channel in the Controller-Scoped Tag collection changing as you would expect?

 

Just some things to check. There are more but this will get you rolling.

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13 hours ago, Filthy McNasty said:

Hi Filthy, Thanks for your inputs. Yes we used fluke multimeter as a load, it reads a 12mA out but it wont responce to any value keyed. yes i used another channel but this time it only  gives 4mA with same behavior not responding to any raw value keyed. I used the IO configuration to set all parameters but have same result. not sure if thier are other settings in the dropdown list in Data.

Thanks a lot for any inputs.. 

1

 

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" Yes we used fluke multimeter as a load, it reads a 12mA out but it wont responce to any value keyed. "

For the record, unless it's a process meter it probably doesn't offer itself as a suitable load. Modern meters are at least 10Mohm impedance. Hardly a load. I would use an actual load device (like a valve positioner, recorder, 250 ohm resistor, etc.)

Try another identical output module if you have one. If you get the same results, I would verify the wiring or way you're trying to measure the current.

If the module isn't defective or inhibited it should have changed the sourced current when you forced the output.

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Your issue is pretty simple. The default for the 1769-OF4 is -10 to 10VDC outputs. When you change it to 4-20 mA and leave it's raw proportional scaling (-32767-32767) the default for the out put data tag stays 0, or half scale, 12 mA. You need to change this under controller tags to -32767 on all 4 outputs. When you download all 4 outputs will be at 4mA. Then you can write code and modulate the output as you choose between 4-20mA.

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