Hello,
This is a simple VI to detect an edge from the channel "Vent Signal"
(AI1) and send out a trigger pulse on channel AO0 (or several, up to 4)
which is detected by connecting AO0 to AI6. The AI6 channel is
called Trig_Pulse. The simulate signal VI is being used to
generate a signal on AO1 that is being fed into AI1, under normal
conditions AI1 would detect a signal from an external device.
This VI is part of a larger program that I have extracted it
from.
We are using a BNC-2110 breakout box, and this VI will only run as
intended if there are BNC cables run from AO0 to AI6 and from AO1 to
AI1, for the reasons described above.
Essentially the problem is that after running the program for about 30
seconds the generation of the test pulse starts to lag behind the
signal, so that even though the edge detection is still working
properly and fast, (as indicated by the Edge Detected indicator
coinciding with the trailing edge of the Vent_Signal signal) there is
latency before a trigger is generated.
If anything mildly CPU intensive is done while the VI is running it
will provoke this reaction. Additionally, the trigger will not
stabilize, once the trigger has started to lag, the latency between an
edge detection and generation of a pulse continues to grow
larger.
An example of correct/desired operation can be seen in correct1.jpg,
the small, fixed amount of latency is acceptable. The problem is
illustrated in wrong1.jpg, note how the time between triggers continues
to increase and lag further behind the edge of the vent_signal.
Please ignore the noise on the other 4 channels, as I mentioned this
has been extracted from a larger VI.
This code is being converted to run in Labview 7.0 from Labview 6.1. It worked properly in 6.1 on a slower machine.
I have tested it on another Labview 7.0 system an observed the same problem.
I'd appreciate any suggestions you might have for solving the problem
