Noise issue after PLC migration (1771-IFE to 1756-IF8)

[Amber Heng]

Urgent!!

Hi all I am a newbie here. Currently I am migrating from plc-5 to controlLogix. When 1771-IFE change to 1756-IF16, I am getting a reading of -1023 (fluctuating) for all the channels. This is a single ended configuration with the AB conversion kit. I have checked the conversion kit and everything is correct. I also measure mA from the 1756-IF16 terminals, the readings are correct but yet I am still getting the fluatuating -1023 value in the studio 5000.

I have no idea what to do. Appreaciate if anyone can help.

 

[ASF]

Have you got the i RTN terminal from each channel connected to a RTN terminal? I find the easiest way to do it is to connect one of the RTN terminals to 0V, and then connect each of the i RTN terminals to 0V as well as needed.

Also check the scaling in the card's hardware configuration in Logix Designer. If this hasn't been set up yet it could be causing what you're seeing.

 

[Amber Heng]

Have you got the i RTN terminal from each channel connected to a RTN terminal? I find the easiest way to do it is to connect one of the RTN terminals to 0V, and then connect each of the i RTN terminals to 0V as well as needed.

Also check the scaling in the card's hardware configuration in Logix Designer. If this hasn't been set up yet it could be causing what you're seeing.

I had loop the i RTN together to the RTN. And double check the scaling. I have put 4 to 20mA equals to 0 to 4095

After that I took out all the channels wiring and just hook up to just 1 channel and try. I got 4244 for all channels.

 

[labeledas]

What mA value are you expecting?

Are you sure it's wired correctly, what is the model number of input device?

and you are sure its set for current and not voltage? just saying because if wire off detection is enabled it would throw all your channels to high saturation in voltage mode 20.58mA of the 4244 in your case.

 

[robertmee]

You're wiring is wrong and each channel is reading 0ma...since 4ma = 0 and 20 ma = 4095 then 4095/16 = 255.9....you're 4 ma under at 0ma so that's -4×255.9 = -1023. Fix your wiring. Or when you installed the module did you select single ended or differential? An easy way to tell is on the channel configuration tab do you have 8 channels or 16?