I have a PXI System (PXIe-1071 Chassis, PXIe-8133 RT Controller) with two PXI-5114 digitizer cards.
I need to have a triggered acquisition, i.e.., I have to start acquisition when the voltage in the channel reaches a particular level ,( i.e..,when there is a pulse in the channel), and read a particular no. Of samples(record length), then wait for next pulse to arrive, and repeat the acquisition.
For my application, Pulse Repetition Freq.(pulses/Sec) is 40 Hz and upon each pulse, I have to read 8000 samples at a sampling rate of 10MS/s per channel. So I am configuring an Analog Edge trigger with the channel (in which the pulse will appear) as trigger source and pulse amplitude as trigger level(threshold).
But when I acquire data with trigger, the CPU usage goes very high. The PXI controller is a RT controller with 1.73 GHz Intel Core i7-820 Quad-Core processor. The CPU usage of the four CPUs are varying randomly, from 20% to even 98%.
This problem is seen only when configuring acquisition with Analog Edge Triggering . If I configure Immediate trigger(it will not wait for trigger pulse), the CPU usage is not exceeding 15%. I have tried External Trig also as Trig Source, but no improvement.
I guess lot of CPU is being consumed to monitor the occurence of trigger.
Is there any solution for this problem?
I attach the acquisition VI here, which will run in RT Target.
Please let me know if any more details are required.
