NI 9401 switching frequency

[CAVR87]

Hello fellow LabVIEWers,

I have a problem in understanding the expression "switching frequency" in the spec of the NI 9401.

If I use all eight kanals for inputs, it is stated that the switching frequency will be down to 9 MHz.

So does this mean that I can not use the DIs in a SCTL running on 40 MHz, or does it rather mean that I won't be able to measure frequencies exceeding 9 MHz but still get an input corresponding to every singel channel on every tick, even though it might be still high when the input is allready low?

I'm using a cRIO-9074, and my incoming TTL signal is in the range of 10 kHz. I need this extream oversampling to optain a good accuracy. without using a two counter method.

Thanks!

[Julien_De_Freitas]

Hi CAVR87,

In the specifications you can read:

"

Maximum input signal switching

frequency by number of input

channels, per channel

8 input channels.......................... 9 MHz

4 input channels.......................... 16 MHz

2 input channels.......................... 30 MHz"

It means if you would like to measure 8 input channels, you are not able to measure correctly a signal with a switching frequency higher than 9 Mhz.

In your case you are in the range of 10 kHz so you can easily measure it with this module.