DIO Pattern with external clock

Question

I use Pattern Input with external clock, I only wire external clock to REQ pin, I see how frecuency vary, but I do not receive data but the one that was latched last time, Do I need to wire something else in order to receive correct and continuos data? I think I just need a singnal to get data latched every time I require trought external clock. What do I have to do to get my application running?

Answer 1

It sounds as though you are using a NI-653X data acquisition board to perform Pattern Input. When performing Pattern Input, data is transferred upon the rising or falling edge (user configurable) of each clock pulse. This clock signal can be externally provided or internally generated. To use an external clock signal of up to 20MHz, simply connect the signal to the REQ pin as you are doing.
I recommend trying a LabVIEW shipping example already set up to do pattern input. The particular example I am thinking of gives you the option to try either an internal clock or provide an external clock. I would recommend trying each option. I do not know which version of LabVIEW you have but will provide the path to the example in LabVIEW 7; the path is very simi
lar in earlier versions of LabVIEW:
Help >> Find Examples >> Hardware Input and Output >> DAQ >> Digital Input and Output >> 653x >> Cont Pattern Input.vi
I hope this helps!
Sonya