where do I connect the endevco pressure transducer wirings using PCI-6250,SCC-LP04,SCC-A106 and SCC-FT01 in SC 2345 / SCB 68

[Migs]

Hi,

We have purchased LabVIEW 8.2 with PCI-6250,SCC-LP04,SCC-A106, SCC-FT01, SC 2345 and SCB 68.

This will be used to measure pressure  using endevco pressure transducer.

 I'm a newbie in LabVIEW and I don't know how to connect this things. I had attended the Basic Labview training but it only focussesd on programming.

PCI-6250 is already installed including SC 2345 wiring.

My problem is where do I connect the endevco pressure transducer wirings using SCC-LP04,SCC-A106 and SCC-FT01 (2 pcs.)  in SC 2345 / SCB 68.

I hope somebody may help me.

[Luke_G]

Hi Migs,

Welcome to the world of test and measurement. It looks like you've picked a good project to start with.
If I understand your question correctly, you are trying to decide which of your SCC modules you should connect your pressure transducer to.

Briefly, the modules that you listed have the following characteristics:
LP04- Low pass filter modules remove high frequency (quickly changing) characteristics of your signal. The LP04 attenuates signals above 1kHz.
AI06- This analog input module accepts an input of up to 0.1V and attenuates any signal components that are faster than 10kHz.
FT01- Feed-through modules do not provide any signal conditioning and are used to simply connect your signal to your DAQ card (much like your SCB 68.)

The correct module for this application will depend on the nature of your signal. As long as the signal from your pressure transducer is less than 0.1V, the AI module is probably what you need. You will want to sample at a rate greater than 20 kHz (twice the frequency of your filter) to prevent aliased signals. I recommend that you take a look at Signal Conditioning Fundamentals for a good explanation of signal conditioning concepts.

I also recommend that you take a look at the SCC Quick Start Guide. Step 6 is particularly useful as it describes how to connect the modules to the 2345 carrier. Step 7 explains how to configure your device in MAX so that you will be ready to acquire data in LabVIEW.

Please repost if you have a more specific question.

Thanks,

[Migs]

Thank you Luke I learned a lot from your idea.

Had checked the pressure transducer’s signal output from it's specifications and it I found out that the full scale output is 300 +/- 100 mV, 225 mV respectively ( two transducers).

Will my SCC- AI06 be damage if I will use it since the signal voltage is greater than 100mV?

What shall I do next?

[Luke_G]

To be honest, I'm not sure if the AI module will be damaged.  My thought is that the DAQ device (PCI-6250) would be the first one to break.  In either case, DAQmx will clip your reading and prevent you from seeing anything outside the safe range for the device.  So in other words, you'll probably want to get a different SCC module.  I'd recommend the AI05 which has a range of +-1V. 

A cheaper option would be to use the FT01 that you already have.  The PCI-6250 has programmable gains, and can be set to various input ranges, including +-0.5V.  Keep in mind that it is better to amplify your signal nearer to your sensor to increase your signal to noise ratio. 

[Migs]

Thank  you Luke. May I use the LP04 ( low pass filter) as a second stage following the FT01(first stage)?

[Luke_G]

Hi Migs,

You're welcome.

Actually, if you are going to use the LP module, you don't need to use the FT module.  The LP module accesses input lines of your daq card the same way that the FT module does, but adds the filtering capabilities.

[Migs]

Hi Luke,

Had successfully connected the transducer to the LP module.  Had check on the MAX and it's working well.

Currently I'm working on the LabVIEW program.

May you recommend some link ( LabVIEW example program)  that would help me find similar program that I may use?

Thanks for your technical knowledge, It helps a lot even a new user can understand on how to set-up NI products.

[Luke_G]

Hi Migs,

I'm glad that the device is working for you. 

I recommend that you look at the examples in the Example Finder that ships with LabVIEW.  It's hard to point to a specific example without knowing all the specifics of your application, but a good general-use starter VI is "Cont Acq & Graph Voltage".

Let us know if you have any further questions.