15 temperature sensors and compactDAQ

[rk_t]

Hello,

I am aquainted with labview but not very well versed with programming techniques, hence my question might be a very basic one, but I would really appreciate your help.

I have an application in which there are 15 temperature sensors (thermocouples), a few digital I/O's and a 3-4 analog I/O's

I have been advised to use compactDAQ by NI people.

So when I searched online a bit, i realized that along with Labview I will need RT module as well as FPGA module. I also read a few white papers.

However after seeing a few videos on youtobe they acquire it by a traditional method us DAQ assistant or DAQmx I am a bit confused as to what I will really need.

Also I will be acquiring data from 15 different thermocouples every 1 sec and at the same time, I will be doing different operations such as acquiring analog data, digital data, etc. 

Can you please advice programming technique suitable for this?

Thanks and regards,

Rohan

[vsenthil957@gmail.com]

Hi rohan

              You dont need to use FPGA module for acquiring data every 1sec. you can use normal DAQ which will go with you No of inputs and Outputs.

[rk_t]

Thanks!!

Can you advice a programming technique?

[Dennis_Knutson]

There are numerous examples for DAQmx that come with LabVIEW.

[rk_t]

Thank you for your response Dennis.

I have used DAQmx couple of times, but did not find a way where I can acquire so many inputs at different rates.

I am havin trouble finding the right technique suitable for it.

Regards,

Rohan

[GerdW]

Hi Rohan,

so you would use 3 DAQmx tasks: one for thermocouples, one for analog, one for digital.

When you really have "I/O" (input AND output) you need two more tasks as you cannot have inputs and outputs together in one task…

Each task can use it's own sample rate. (Sometimes the hardware has some limits on the number of clocks used, there are AppNotes available at NI's website.)

[vsenthil957@gmail.com]

Hi rohan

              you can look it Maser-Slave architecture, and run the slave with timer for different rates of acquisation .

[Sam_Sharp]

LabVIEW RT and FPGA is only really necessary for programming the CompactRIO (NIs embedded controllers) - you can write RT code on (some?) CompactDAQs so you can use them as a standalone datalogger.

You can just connect a CompactDAQ to your computer via USB or network over ethernet and program it using DAQmx from LabVIEW on your PC.

[stevem181]

Hi Rohan,

As others have said, you don't need RT or FPGA.Based on your requirements cDAQ is a viable option.
It sounds like you don't have the hardware yet so based on this assumption, I have some suggestions.

If you are not familiar with Measurement and Automation Explorer (MAX), now is a good time to check it out.
You can set up a simulated chassis and cards which you can use to run your code (in simulation).
Your simulated chassis can even be used with some of the example programs that come with DAQmx.

To set up your simulated chassis, open MAX. right-click on "Devices and Interfaces" - select: Create New
Choose your chassis, then right-click your chassis and select modules (Configure Simulated cDAQ Chassis..).
If you decide to use other DAQmx compatible hardware later, it's no big deal.

A good trick is to use DAQ Assistant to create a task, test it in simulation, then have it "Generate DAQmx Code".
So for your requirements, you could set up a task with 15 thermocouple inputs, then look at the code. 
You will see how a "For Loop" can be used to create multiple channels for a task.

Next, check out the example program: "Analog Input - Voltage and Thermocouple in a single task.vi"
This VI shows how to combine two operations (Voltage Input and TC Input) into one task.

These suggestions don't address the overall programming of your application, but should get you started on

understanding the DAQmx programming. Crawl, walk, then run.

steve

[r_te]

Thanks a lot everyone for your help!

I will try doing the aobve things.

Thanks one again,

Regards,

Rohan