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Architecture and DAQ help

Hi,

 

The System:

I have  a system with 20 thermocouples, a pressure transmitter, 3 magnetic valves and 2 heaters that has to be interfaced with a LV application. I am using a PCI 6289 DAQ, SCXI 1102c and 1303, 1302. This is done at a university lab for Thermodynamic study of a droplet.

 

to do:

I have to acquire Thermocouple and pressure values, calibrate it with formulae inside VI, display and log it. The magnetic valves must be controlled on pressing FP buttons and the heater current should be changed on front panel.

 

My Questions:

1. I am trying a architecture with 5 loops as you can see in the attachment and 4    Queues(represented by coloured arrows). Is this good enough or an over-kill??

2. I should acquire 1k continuous samples, at the rate of 2KHz. Must I use DAQ Assistant or DAQmx to implement this.

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@GoKu25 wrote:

I should acquire 1k continuous samples, at the rate of 2KHz. Must I use DAQ Assistant or DAQmx to implement this.


If you ask that way, I'd say you must not use the DAQ Assistant, but should learn how to use DAQmx.  There is a series of tutorials on DAQmx, my favorite being "How to use 10 functions in NI-DAQmx ..." (you can search for this phrase on the Web and you'll find it).

 

Bob Schor

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Hi GoKU25,

 

for your architecture: I think what you are trying is fine for the scope of your application. What you are describing is the Queued Message Handler. This architecture is perfectly able to do what you want to achieve, as can be seen in the continuous measurement and logging example from the "create project" screen.

For the aquisition itself, I would also strongly suggest the DAQ functions and not the assistant.

If you need further help, the two courses "LabVIEW Core 3" and "Data Acquisition and Signal Conditioning" are ideally suited to the task that you planing.

Cheers,

Niko

Niko NR
Systems Engineer, National Instruments
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Hi Niko,

Thanks for the reply. Is "Data Acquisition and Signal Conditioning" course not availble in Online training? I have access to LabVIEW Core 3

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Hi GoKu25,

I don't think so, because you need the appropriate hardware for that course to follow through the exercises. Since you said you are in a university, you might have access to training at NI as well.

You can send me a private message if you need any further information and I will inquire for you.

Cheers,

Niko

Niko NR
Systems Engineer, National Instruments
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I have finished 70% of my application. I have individual sub vi's for acquisition, Control and logging. The application 2 Independent processes. One acquires data, calibrates and logs and displays. The other controls Valve open/close state. These controls are handled with in the Queued Message Handler architecture since only a single run of the respective code is required. Then the thermocouple data should be calibrated, analyzed for various conditions like high temperatures, heating/cooling based on temperatures...I do this in the Display loop- not within a subVI, given the number of Indicators, there would be too many references to wire into a sub vi- where everything is cluttered. I want to know if there is a better way of programming it.

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