the problem of signal leakage in BNC 2110

[khan1]

I am facing the problem of signal leakage in BNC 2110 while trying to read multiple inputs using DAQ assistant. When, i try to read my input signals: I observe that the high input signal is leaking into other input signals which have low voltages .I tried to ground the BNC input after the high input signal but it did not make any difference. Can anyone help?

[Henrik_Volkers]

crosstalk is specified , see spec.

could be also a crosstalk in the wires to the DAQ , or the setup (capacitive or induktive coupling, or even a groundloop (follow the flow of the currents))

[khan1]

Thanks Henrik Volkers .I did sort out the ground loop problem and the BNC 2110 that i am using fro reading my inputs are shielded from noises. My DAQ card was the source of the problem while reading inputs.I have overcome the signal lekage some what by using 2 DAQ card.Thanks any way for your reply

[BB.]

Hi khan1,

Just to clarify your problem one analog input which has a high voltage is leaking into another input signal of a lower voltage. Have you correctly set the FS/GS switch on your BNC 2110? If you are measuring floating signals (no reference to ground) then you need to set it to FS, if you are measuring a signal with reference to ground use GS. What exactly are you measuring? The noise you are experiencing could be down to wiring, there is a good resource on here: Field Wiring and Noise Considerations for Analog Signals.

Also a good way to test for correct function is to use the test panels as well as a self test in Measurment and Automation Explorer (MAX). Do this by loading up MAX, go to My System >> Devices and Interfaces >> Click on you DAQ card connected to your 2110. Then click self test, and use the test panels. Test with individual analog inputs and see if you get expected results on each channel.This could isolate if there is an internal issue with the hardware.

I hope this narrows down your issue, please let me know how you get on.

Kind Regards,

[khan1]

Thanks  BenjaminB  for the reply.I have done the procedure u posted and it did not work.The DAQ cards are talking to each other and i am sure these cards are the source og signal leakage

[Steven_K.]

Hi khan1,

It sounds like you are experiencing ghosting. This can be caused by high impedance sources. What impedance are the sources you connecting to your DAQ device? Here is a good guide that explains why ghosting occurs and how to decrease it in your measurement:

How Do I Eliminate Ghosting From My Measurements?