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Readout Speed using DAQmx Read/Write

Hi,

 

I'm using LV version 8.5 with an USB 6251 OEM board connected. Right now I'm working only with the digital IO.

What I want to achieve is the following:

- System waits for a trigger signal

- When trigger occurs a bit-stream is written out on one pin (port0/line0) and a second bit-stream is read in on another pin (port0/line2). This has to be done at the same time, and therefor I use the same internal clock (ctr1).

 

I want this to happen (relatively) fast. Trigger comes in between 10kHz and 100kHz, clock for the bit-stream is set to 1MHz.

 

I can write the bit-stream and I can read it (for test-purposes I just shortcut the write-pin to the read-pin and see if I get the same bit-bitstream that I send out). My problem is that even though I use the same clock for read and write DAQmx functions and I start them at the same time, there is a delay of ca. 7ms between writing and reading. And the time it takes for a DAQmx rear/write functions to run is somewhere around 20ms.

Is there any possibility to speed things up?

I'm adding a screen shot of the central part where I read and write the bit-stream. I added a time-delay before the start of the write function as an attempt to synchonize the read/write operations.

 

I'm very greatful for any help.

CG

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