Pre-Store capability on PXI-6551?

[scrib]

Hi,

Is there a pre-store capability on the PXI-6551? We are using the module to replace a logic analyzer and we need to be able to acquire and perform a hardware compare of a set of samples before the trigger occurs.

Thanks in advance,

Joe

[Chris_D]

Joe,

Yes, you will have "pre-store" capability on the 6551. You can do this be setting up a Reference Trigger and configuring the number of pre-trigger samples you want.

[JaredW]

Joe,

Chris is mostly correct on his reply to you. If you are only using the 6551 as a logic analyzer then yes, you can set up the acquisition such that you are able to retreive pre-trigger samples.

However, you mentioned in your post that you wanted to do hardware compare on the pre-triggered samples. The hardware compare feature of the 6551 does not allow for using a reference trigger. The hardware compare engine must be triggered with a Start Trigger, which doesn't allow for pre-triggered samples.

Is there a specific reason you need the "pre-store" ability? How is your system setup? Maybe there is a way we can get around the need for a comparison of the pre-triggered samples. Also, does your current logic analyzer support hardware compare? If so, I'd like to know which logic analyzer you have.

-Jared

[scrib]

Jared, Chris:

Thanks for the replies.

The reason we need this capability is because the trigger edge that we're using signifies a "rollover" event where we'd like to make sure the UUT is generating data properly through this "rollover" event. This trigger occurs at 1.5 second intervals and we're acquiring data at 10MHz.

The logic analyzer does not support hardware compare which is why we converted to the PXI-6551 -- to decrease our test time.

Regards,

Joe