I have a question about the threshold voltage for the NI 9401 to recognize a pulse. Can that voltage be configured? Is there a set value of 2.5 volts or does it have to be set to 5 volts for a pulse to be detected?

[tmassey]

I have a question about the threshold voltage for the NI 9401 to recognize a pulse. Can that voltage be configured? Is there a set value of 2.5 volts or does it have to be set to 5 volts for a pulse to be detected?

[AnalogKid2DigitalMan]

Per the specs for the 9401:

Digital logic levels

Input

Voltage .................................5.25 V max

High, V

IH..............................2 V min

Low, V

IL ...............................0.8 V max

Thus any voltage between 2V and 5.25V on an input will be considered as a logic high. Any voltage between 0V and 0.8V will be considered as a logic low.

-AK2DM