Finite Measure with 2 boards 6602 and 6 DMA Channel Counter Buffered - error 200141

Question

Hi all,
First .. I'm a beginner with LabView and I hope to explane myself in good way cause I'm italian..
I red all the post about the error 200141 and check the suggested solutions (also the way to ignore the error), but I want try to ask for a differet one..
What i'm trying to do is to aquire 6 encoder, 3 on the first board PCI 6602 and 3 encoder on the second board on DMA channels.
The encoder generate 90000  X4 = 360000 pulses x revolution and the max speed rotaion is 4 RPs.
Cause I need to store in a bin file all the pulses from the encoders, i generate a trigger of 1.5 MHz to get all the samples at the max system speed (360000 * 4 = 1440000 pulses  x sec).
I think to have reached the limit, and maybe is not possible do better.. actually the 2 PCI 6602 works with 1,0 MHz of trigger and the system store in 6 files 4000000 of samples during
the finite measure of the angular position on 6 channels.
The trigger is not yet sync between the 2 PCI cause I'm waiting for a RTSI cable to put in the PC...
In Your opinion is possible to find a alternative way to acquire these encoders ?..
Thanks

Answer 1

I also doubt if you need to capture every single increment from each encoder.  I'll discuss this more below.
Further, many earlier discussions suggest that counter tasks can sustain data transfers merely in the 100's of kHz, with *maybe* a possibility under special circumstances to slightly exceed 1 MHz.  Your boards have very small hardware buffers (either 1 or 2 samples worth), causing the PCI bus usage to be very frequent and therefore less efficient.
Now, let's go back to your sample rate.   You've got encoders which suggests that you're dealing with a physical system.  Physical systems have inertia, which limits their useful bandwidth.  In my experience, it's quite unusual to care about motion artifacts beyond the 10's of kHz.  The inertia just doesn't allow anything significant to happen at that rate.
So, if the physical bandwidth of your motion system is, say, 5 kHz, there's a rule of thumb suggesting to measure at 10x when possible.  So that'd mean 50 kHz sampling.  50 kHz x 6 channels on the PCI bus may be possible.  Multi-MHz sampling won't be.
Can you describe the physical system a bit?
-Kevin P.