How to get rid of the DC offset?

[Xiang00]

Hello everyone,

I use USB6211 to control a power supply (PS375 SRS) through a wire lead BNC cable.

The problem is that when I sets 0V on "Gen Voltage Update.vi", the monitor of PS375 showes 9-13V offset on its numeric display for output voltage.

When I want to set 100V, then the display showes 109-113V.

I found that

1. When I shutdown the PC, the PS375's numeric display showed 0V

2. When I turn on the PC, the PS375's numeric display showed 9-13V

These are the all information I have.

Could you help me?

[AnalogKid2DigitalMan]

That SRS unit is a 20KV supply, correct?

0-10V in = 0-20KV out. You are seeing a 10V output offset, that translates to 5mV input offset.

If you have a DMM or scope, monitor the DAQ output when connected to the SRS to see if there is any DC and AC components when the DAQ is set to 0V output.

That fact that you see an output offset when the PC is turned on leads me to think it could be noise on the 5V PC power supply.

Have your tried using the RS-232 port for programming the SRS? This may be more accurate than using an analog control voltage.

-AK2DM