pci-6534: Pattern I/O using Start-/Stoptrigger with external clock

[AlexH 33]

I'm using a PCI-6534 card in pattern input-mode with singlebuffering for 16 bit samples with hardware start-/stoptrigger on lines ACK/STOPTRIG and an external clock on line REQ.

When the starttrigger occurred a x amount of data is to acquire until the stoptrigger is received. The x amount of data is not predetermined. How can i determine the amount of data currently read between a start- and stoptrigger ? The function DIG_Block_Check(...) returns only the error-code for the stoptrigger.

How is the data transfered from PCI-6534 to the buffer ?
I tested a few acquisitions but the relevant data starts not on the first address of the buffer.

Thanks for any help.

[bman]

Alex

When using a Start and Stop trigger with Pattern I/O using the PCI-6534 device, it does not work as one may think. It starts reading in data into a circular buffer when the start trigger comes in. The data will continually overwrite itself in the buffer until the Stop trigger comes in.

When the Stop trigger comes in it keeps x amount of data from the cirular buffer and then aquires x amount of posttrigger data.

Since you have an undetermined amount of data to acquire, the best solution I can think of is to use a counter either on an E-Series board or a NI 660x board to generate the clock. You can start this clock from a start trigger and stop it on a stop trigger. There is already an example that does this that I have attached below.

Brian