NI9401 and linear encoder

Hi,

We use NI-9401 module on cDAQ-9189 device in slot 5 to measure a linear encoder (Heidenhain).

I used the drawing design specified there : http://www.ni.com/tutorial/7109/fr/

Under NIMAX, I have created a virtual channel to measure a linear position.

Then I have created a counter task for linear position (with call to my virtual channel).

If I set up my task with option one sample on request, it is working, but it will not be very efficient with Labwindows/cvi because it creats interrup.

I am not able to use continuous samples option ! : internal clock is dimmed and the other clock choises don't work.

Have you got an idea how to set up my task ?

Thank's