ni usb6212 analog input impedance

[kristos_b]

Hi all,

I have a question about one of ni usb modules. Previously I was using usb6009

and because it has low ADC input impedance (144k) I was forced to use external

buffers and some other circuitry. Now I have in the Lab the usb6212 module

which has ADC input impedance 10GOhm when the device is on and 1200 Ohm

when it is off (according to this http://www.ni.com/pdf/manuals/371932f.pdf). This

is perfect for my application because I have to measure the line first and

after measurement I have to short the capacitor to get ride the charge

(continuously in the loop). My question is how you actually switch between high and low

input impedance. I tried different things from DAQmx palette but nothing works

for me. I could not find anything about this problem on ni webpage or LAVA.

Could you help me with this or point me to the solution on the web.

Thanks,

Krystian

[kristos_b]

I got the reply from customer support:

"The 1200 ohm off impedance is the input impendance when the device is unplugged from the PC and powered down, there are no options toprogrammatically switch to this impedance."

No switching of the input impedance unfortunately...