Hello Everybody
First of all: I am a LabView newbie!
I need to acquire several signals (pressure temperature) of a four-stroke cycle diesel engine.
I am using:
- Labview 7.1
- DAQCard-6024E
MY PROBLEM TO SOLVE...
In order to analyze the long term behaviour of piezo-resistive pressure sensors I need to acquire up to 16 analog signals.
The acquisition should be started by a digital TTL signal from the crankshaft. This impulse is given once per revolution, but the 4 strokes cycle engine needs 2 revolutions (720°)to be complete. So I need to distinguish between this two impulses (1st impulse --> 0°; 2nd --> 360°). This could be done by looking at the pressure in the combustion chamber. The pressure there at the begin of the intake stroke (1st impulse) is about at atmospheric pressure, while the pressure at the begin of the work cycle (2nd impulse) is much higher.
MY QUESTION...
How can I make it possible to start a data acquisition with a digital Trigger only if the value of an analog input channel is below a predetermined value?
The application should then acquire a number of scans, stop, and start very short time afterwards again. (This should happen about 50 times, afterwards the standard deviation and so on will be calculated, ...)
CAN SOMEBODY HELP ME?
I have attached my current file. The acquisition works, but cannot distinguish between the trigger signals. It can take a number of scans, starting with an randomly chosen trigger, it take the scans, stops, and is exactly ready when the "same trigger" (1st) occurs again. Unfortunately I need now to check and sort the data for the first trigger.
I woould be glad if somebody helped me, or give me any tipps of perhaps already existing software.
Thanks!
Woodi
