Minimizing PCI resource usage

Hi, I'm using 2 cards for a specific application. By changing the voltage on the analog outputs (I use both analog outputs) of a pci-6251 I move a scanning mirror to a desired position. After I find the desired position I just leave the voltage output as it is. At this point I use a second card to count photons (not a NI card). My problem is that the second card doesn't  run properly when the pci-6251 is supplying voltage simultaneously. When I turn off the program that controls the voltage output on the pci-6251 the second card works fine. I realized that both cards compete for the computers resource usage. When I don't use the pci-6251 I can have as many as 2M counts/sec on the other card and when I do use the pci-6251 I can only have ~ 80k counts/sec. I don't understand why the pci-6251 uses so much of the computers resources just to keep a constant voltage output. Is there a why to solve this problem so the 2 cards work in harmony with each other? Thanks for the help,Eyal

Hi Eyal,&nbsp;Are voltage values being constantly written to the analog output when the mirror is in the correct position? This analog output voltage will remain constant until it is changed so one thing that may reduce the use of resources is to write the final voltage values to the PCI-6251 and then close all references to it. <a href="http://digital.ni.com/public.nsf/allkb/FA35E2F2B29A75638625727E0001F3F4?OpenDocument" target="_blank">This</a> article gives a bit more information about this. Hopefully this will allow your other card to run as quickly as possible. Let me know if this helps. &nbsp;Regards,KentApplications Engineer