Creating a Pressure - Volume Diagram for an air compressor. Please Help!

[Jason@Quincy]

I'm fairly new to Labview and desperately need some help. 

My hardware:

cDAQ-9172 with a NI 9233 module in slot 1 and a NI 9411 module in slot 5.  I am using 3 ICP type pressure transducers hooked up to the 9233 that is measuring pressure.  Transducer 1, 2, and 3.  Hooked to the 9411 is a rotary encoder.  It is set up to measure 360 derees, and has a z index once per revolution that will be set to top dead center with a cylinder on an air compressor.

My software: Labview 8.2.1

What I need: 

First task:

I have psi transducer 1 and 2 set up on the cylinder head.  1 on the intake side and 2 on the exhasut side.  I need to graph both pressures over 360 degrees crankshaft rotation (0 degrees or z through 360).  The only data I need to see and save to a file is the two pressures graphed over 0-360 degrees crankshaft rotation.

X=0 (z) through 360 degrees on the encoder 

Y=two pressures 

Second Task:

I need to graph pressure transducer 3 over the cylinder volume for 360 degrees. 

X= Pressure 3

Y= Piston Volume

Apparantly for this task I would have to enter the piston diameter and the stroke to calculate the volume.

[Conseils]

Set the coder to trigger the A/D sample aquisition from the pressure transducers. You do this by configuring the aquisition to be triggered by an external clock source; the new DAQ wizards take you through how to set this up and connect the hardware with pretty diagrams.

You will now get a sample for every angle event from the coder, of course what happens inbetween is anyones guess but hey-ho its the same for any discrete sampling system!!! ... you can always do some runs with pseudo continous logging if you are nervous. All you then need to do is set up the start count from the index pulse and you have angle versus presssure related to TDC... Of course it won't go round smoothly and may well go backwards a bit as well !

Message Edited by Conseils on 11-12-2008 01:46 PM