Triggering in 6534

[Vishal]

Hye to all,
friends some questions are there related to triggering in input & output operations.

1. )Why it is not possible to give start & stop trigger both with the pattern match or mismatch?
2. ) what will happen if i configure like that?
3.) Why triggering facility is not given with handshaking input/output?
4. ) if i am using finite output operation, how can i use pre-trigger & post trigger points?Please explain this briefly. If i configure like that with buffer control.vi will i have to continuously output data to wait for stop trigger?or i have to load the buffer only once?In short i am confused with using pre & post trigger point algorithm with finite output. Please help me.
Hoping best answers from best friends,

[rgharrison]

Hi Vishal,

Here is some help:
1) There are 2 different signals to Start and Stop an acquisition (STARTTRIG and STOPTRIG). When you configure a Pattern Match trigger, the pattern match circuitry applies a digital signal to either the STARTTRIG or the STOPTRIG lines using a switch. For this reason it can not be applied to both.
2) It will either error or not operate as expected.
3) Triggering in Handshaking Mode is not needed because operation (input and output) is defined by the handshaking signals. The operation won't start until it receives the appropriate handshaking signals etc. Therefore handshaking is like continuous triggering except only on the handshaking control lines.
4) You can't use pretrigger points on an output. How would you know when t
o start outputting data since you don't know when the trigger is going to come. For example, lets say you have 10 pretrigger samples for output. When you start your operation, it will start outputting those samples. When it finishes outputting the 10 pretrigger samples and doesn't receive the trigger does it continue outputting the rest of the samples or does it wait for the trigger. It doesn't make sense to have pretrigger output on your DAQ board. You can only use post trigger output for finite and continuous applications.

Ron

[Vishal]

But if i configure stop trigger in output operation and if i connect any number to minimum no of scan/update required and if stop trigger comes before that it will show error right?
2.) if i am using finite output for say 1000 samples and i have configured stop trigger, i have connected 0 to minimum required scan/update in buffer control vi so my post triggered points are 1000 right?
Now i will have to give continuous output until stop trigger comes? or it will stop after 1000 samples if stop trigger has not come yet? I think that the first option will work.

[rgharrison]

Vishal,

The there are many example programs for triggered pattern output operation (start or stop). Just take a look at the programs on ni.com/support (Example Code). That will show you how to use the programs.

To answer your other question, yes you can output continuously and then stop and still output post trigger scans.

Ron