How to check if an external clock reference is present?

[Tims]

Hi,

I have an NI5911 flexable resolution digitizer and use NI SCOPE drivers.

I currently use PFI1 as an input for an external 10MHz reference which
works fine until it is disconnected.
The question is can I some how detect an external reference is there, so
when I initialise the device it can make the decision on whether to use
the internal or external reference?

Thankyou Tim

[Raecine Meza]

Tim,

There is no built-in way to accomplish this, but you could create a program that checked for this. For example, configure the program to use the external reference. The read functions for the 5911 have a timeout. So you could set the timeout value for a short value. Then check the error from the read function to see if there is a timeout error.

If there is a timeout, then you can conclude that no external reference was available and you can reconfigure the record to use the internal reference instead. At this point, you'd perform the read function all over again using the internal reference. If there is no error, then you will get your data back as expected using the external reference clock.