Analog output variations

[erivinoth]

Hi,

One of our project using SLC5/05 processor and 1746-NO4I 4-channel analog output module. 4-20ma current output used. When we put 0% (From HMI)we are getting 3ma and when we put 100% we are getting 14ma only we are not getting 4 & 20 ma in 0% & 100%. Output impedance is 250Ohms This output is connected to Quarter turn Modulating actuator. Can anyone give me the solution for this issue.

Thanks,

Regards,
Vinothkumar

 

[TConnolly]

Show us a screen shot of how you are scaling your 0 to 100% for the output in your PLC program, or better yet, zip and post your program.

Have you checked your PLC power supply load? You can check that in RSLogix500 under IO configuration. Click the power supply button and select the correct power supply. Loigx500 will indicate if you have a large enough power supply for the configured IO.

Have you checked the switch on the Analog Output card that selects internal or external power?

What happens if you disconnect the wiring and attach a 250 ohm resistor?

Lets start first with the program though, since scaling is a common error.

 

[Mickey]

And here is the scaling info. If needed.

 

[erivinoth]

Hi,

Thanks for your reply, Actually this is existing system which is installed 10 years before. Worked well. This PLC is Password protect so i could not see the program. Totally there are 8 actuators, all are same function. other actuators are working fine. They are used internal power supply.

 

[shooter]

swap cards, most probably the power supply of the card is no good.