6534 input output delay

[mlloyd]

I am trying to combine the two example VIs Burst Output and Burst Input to create one VI that will output data and then wait to receive a data packet back. I have a flat sequence structure with two frames. The first contains the burst output, and the second contains the burst input. My configuration parameters are all default values except the ports (output is 0, 1 and input is 2, 3) and control groups (output is group 1, input is group 2). I am having a few problems:
1. There is a large delay (at least 10 microseconds) between when the output finishes and the input starts.
2. The ACK asserted by the 6534 when trying to receive data is does not become active until a long time after the 6534 internal PCLK signal becomes active.
3. The length of the ACK signal asserted by the 6534 is very short (on the order of 2 PCLK cycles) even when trying to receive over 500 words of 16 bit data.

Any suggestions on how to get things running more smoothly?

Thanks,
Michelle

[e-Cash-Money]

Hello Michelle,

Is it necessary for the input to wait until the output data is finished to begin acquiring data? An easy solution might just be to simultaneously do the input and output and post-process the data in software to determine which input values correspond to the data packets you were waiting to receive. Basically we would be oversampling the input to make sure we acquire everything and then pick out the important bits afterwards. If this is not a viable solution, go ahead and upload your code so we can take a look at it. Thanks!

Take care,
E.Lee

[mlloyd]

Thanks for your help Eric... I got things running a little faster by removing the DIO Wait VI from the output sequence. This seemed to reduce the wait between when output was done and before input started. Your idea would probably make things even faster but at the risk of requiring slightly more complicated code. I'll give it a try if performance becomes an issue again!