Syncronized Loops not starting

Question

All,
I have process in which I <think> I need to utilized multiple timed loops with synchronization. In one loop,  I am sending a signal low on channel 1, reading a sample on channel 2, and then sending channel 1 high. This repeats every 100ms using a Timed loop.  In the second loop, I am attempting to send out a waveform on channel 3 whose amplitude is updated every 100ms. based on the sample I take in the first loop (using local variables to communicate).
I've attempted to synch the two loops following the shipped example, but what I am finding is that the second loop never starts. The first loop runs immediately and runs as designed. I am not sure if it's the second loop is waiting on something. Perhaps I have my DAQmx tasks setup incorrectly?
(If anyone has a better implementation for variable waveform generation, please let me know that too.)
Any and all help appreciated.
Matthew Pausley
NC State University
Raleigh,NC
Attachments:
tl_091106.vi ‏257 KB

Answer 1

Well, this is very odd indeed. It turns out that your timed loops will start correctly if you add an extra character to the loop names in the string array for the Timed Structures Name input to the VI called Syncronize Timed Structure Start. The reason your first loop starts is that it actually has a carriage return after the name Loop1. You just can't see it because it's not a visible character. If you add a carriage return or any other letter after Loop2 in that string array (for instance Loop2x), then it will start as well. Similarly, if you delete the carriage return after Loop1 in that string array, it will stop starting correctly. I can't reproduce this from scratch, unfortunately, so it's hard to say if this is a bug or not.
Message Edited by Jarrod S. on 09-14-2006 02:56 PM
Jarrod S.
National Instruments
Attachments:
Workaround.JPG ‏23 KB