switch frequency synchron with digital daq mx card

[v1212800]

Hi,

is there any possibility or example how to switch my frequency with an digital signal from my daqmx card. I have a PXI5404 fgen and a PXI 6259 multifunction and a 8176rt controller.

Thanks
Tim

[psisterhen]

If you configure a digital start trigger on the 5404 (set the source to one of the PXI lines, for example) and you change the output frequency during generation, the frequency won't update until another digital trigger comes in.  You can use this to accomplish what you want.  The program would look something like:

configure the 5404 start trigger source to PXI 0
start the 5404
loop
   change the output frequency of the 5404
   use the 6529 to send a digital trigger on PXI 0
end loop

So you will need to set the 5404 frequency in software, but you can control exactly when the frequency changes using the digital trigger.

[v1212800]

Hi,

thanks for the answer. Is the PXI 0 an external trigger or is it via the backplane of the chassis? If not, is it possible to trigger it via the backplane? And I cant find any trigger source PXI 0, only PXI star, PFIO to 3, RTSI 0 to 7, TTL 0 to 7, software trigger VI, external, ECL 0 or 1.

[psisterhen]

PXI triggers are the chassis backplane lines.  They are sometimes referred to as RTSI in the driver (since that's the trigger and clock bus used in PCI).  So try one of the RTSI lines.

[NeilF]

Just to make it very clear, PXITrig0 is the same as RTSI0, PXITrig1 is the same as RTSI1, etc.  They are the backplane trigger lines that all devices in the PXI chassis share.  The PFI lines are the front panel inputs/outputs.  They are typcially labelled PFI0, PFI1, etc.

Neil

[v1212800]

@ psisterhen,

I have realized your loop, but it isn't faster than 2 microseconds... Is there a possibility to make it faster?
I tried timed loops and I tried an external digital trigger to set up a nw frequency, but to set up a new frequency, it has to be software-timed.
Is it really the last end, these 2 miliseconds?