Hello, First of all, I would like you to look at the graphs below. 1 record takes 53 us. This value is fixed. Records were triggered by a digital pulse train of 63 us period (about 16KHz frequency). Since the rearm time of PCI-5152 card is 8 us, this condition is very reasonable. Ideally, the time needs for one cycle should be linearly proportional to the number of records per cycle. However, a labview application or hardware will need some time to transfer the measured data. The goal is characterize the delay or processing time which multi record fetch vi needs to fetch different amount of data from PCI-5152 board to the PC memory. I assume the larger the amount of data (# of total data points or such) is the more time the application needs. The result denies my assumption. Looking at the graph on the top right corner, the delay (processing time, lag... I seriously don't know the cause of this time discrepancy) actually decreases as the total amount of data the multi record fetch vi handles increases. It is actually the opposite to what I expected. I thought the delay would be proportional to the amount of data and it would be the time to take to transfer the data through the PCI bus (133MB/s). When the number of records per cycle is below 500, the delay per cycle does increase. For the same number of records per cycle, the delay increases as the record length goes up (Tow graphs on the bottom). However, when the number of records per cycle is larger than 500, the delay shows unexpected behavior. The delay per cycle decreases as the number of records per cycles increases. Between 500 records and 1000 records, the delay increases, however, from 1000, the delay keeps decreasing. I have no explantion for this observation. I would like to ask why the delay actually is smaller when the data stored in PCI-5152's onboard memory is larger. In addition, the delay is quite difficult to to characterized since it shows practically no reasonable trend. I would like other high speed digitizer users to help me figure out why this is happening. Thank you.

High-Speed Digitizers

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I tried enabling 'more memory' node and it worked this time but it had no positive effect. It showed the same result.

I attached the test VI I sued.

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