Two boards, differenc clock signals but synchronized...

[ssanto]

I have two boards doing patterin I/O... I need one to output a specific clock signal (2 MHz for example) on the REQ line, I need the other board to have a REQ signal of half that (1 MHz). Is it possible to do this and keep the boards synchronized?

Thanks,
Sal

[June]

Sal:
I can think of a couple options for your application. 1) Use internal timebase for both devices, but use start trigger to start the operation.
2) Use two external counters to generate 2 MHz and 1 MHz signal, since the counters will be using the same onboard timebase, your 2 MHz and 1 Mhz signal will be in phase and synchronized with each other. Use these signals to clock the pattern I/O operation.
3) If you are using PXI 6534 devices, they have onboard phase lock loop circuit, this means that they will be phase locked to the PXI backplane clock. You will need to start both devices with start trigger, and the two internal timebase should be in phase.

June

[Jporter]

June,
I have a problem that may have a similar solution. I need to phase lock the timebases of my 6608 and 6534. Based on your reply to Sal, I understand that if I place my 6608 in slot 2 (to place its oscillator on the PXI backplane) then the 6534 will automatically be locked to it. Is this correct? Or am I making this to simple?
Jay

[June]

Hi Jay,
that is correct. Both the 6608 and 6534 has phase lock loop circuitry on them, which means that by default, they will lock to the PXI backplane clock. Placeing the 6608 in slot 2 will drive the highly stable OCXO to replace the backplane clock of the PXI chassis so that any devices that can phase lock to the backplane will all share the 75 ppb resolution.
June