generating and syncronizing two pulse trains

[Math_]

Hi !

Here is my problem. I'm using a serie M and a SCC2345. I need to generate two pulse trains @ 50Khz (with different cyclic rates), with a precise (and constant) phase between them.

The problem is that the phase between CTR 0 and CTR 1 is constante, but not always the same : it changes if I reboot the Pc, LabView, or sometimes only when I launch the VI again.

I can fix it manualy with the variable "initial delay", but I need to do this every time, and it is not very precise.

Someone has an idea on how to syncronise CTR0 and CTR1 with a constante phase ?

Thanks for your help.

Message Edité par Math_ le 08-01-2007 09:34 AM

[Kevin_Price]

You'll need both counter pulsetrains to be configured to start off the same Digital Start trigger -- then the initial delay parameter should produce consistent results for you.  You can do this by generating your own trigger signal by setting a digital bit low, starting the counter tasks, then pulsing the digital bit high and then back low.  You would need to select a digital bit on port 1 or 2 that also maps out as a "PFI" pin because the triggering must refer to the signal by its PFI identity.

-Kevin P.

[Math_]

Thanks for your help, I did like this, and it works.

But as my system must be entirely automatic, I generate the rising edge of the digital port by the serie M herself at the launch of the VI. In the SCC2345, I linked this port with a PFI with a wire. Not very smart, but it works !

Thanks again !