measuring voltage of digital input

[katona]

hi.

i'm developing a software for a testbench.

(the hardware was developed in the past by another person, and i have to use this hardware now)

i have to read some digital data with a ni usb 6501.

i've measured the voltage levels on the pins and realized that for logical 1 I get about 4,7V, for logical 0 about 3,5V (which after converting into digital is still 1).

Do you have any idea how could I solve this problem?

I was thinking that if I could get somehow the analog voltage value on the pin, the problem would be solved, but I don' know if that's possible.

Thanks in advance.

Katona

[RuedigerE · Accepted solution]

Hi,

on 6501 input low voltage (logical  false) is up to 0.8V and input high voltag is in the range of 2.0V to 5.8V. You have to use a electrical circuit in or a device with a analog input order to solve this issue.

What do you think about a "Schmitt Trigger"

http://en.wikipedia.org/wiki/Schmitt_trigger

Regards

Rüdiger 

[katona]

Thanks.