Daqmx separate multiple physical cahnnels apply equations and collect information

[Nikolian]

Dear People!

I am using a DAQCard 6023E with 16 channels. My purpose is to collect information from a gasifier to find temperature and pressures from 7 of the channels and 4 channels respectively. Forget about the pressure to make the problem more easy.

The readings we get from the gasifier is in miliV amplified by an intensifier while also it adds an offset. When the readings come inside LabView I get all the 7 channels I pass them from DAQmx Create Channel then I add a Sample clock. I start the task with a DAQmx Start task and I put everything inside a loope where DAQmx Read starts to read all the physical channels. Now I need to reverse engineer the mV (which are amplified) by subtracting the offset and divide by the amplifications to each separate physical channels ( for each channel there is a different offset and amplification). When do this I pass them from a thermolinear module to convert it to V to Temp. And this information then passes to a "Write to measurement file" to have a file with all the inform. Then the while loop closes and we have the DAQmx Clear task and the error (very basic).

If I had only one physical channel it will be very easy. I will have to use just a Subtract and Divide module to reverse engineer the mV before passing to the thermolinear module.

The two questions I have is:

1) How is it possible to separate the the physical channels inside the while loop before or after the DAQmx Read ( I don't really know what is best) to apply for each physical channel the appropriate offset (subtract) and amplifications (divide) and then reconnect them so when they go to the "Write to measurement file" to create one file with all the physical channels and not one file for each physical channels?

2) The thermo linear module needs to have a cold junction voltage (for the 25 ambient temp). Does this voltage needs to be in V or in miliV as my input is in miliV? While also inside the Thermoliner module it informs me that it needs microvolt (1000miliV) do I need to change this for the module to work?

The thermocouple I use is a K type with constant value for units (Celsius) IC sensor and Voltage reference. I hope I was not too long to explain you my problem and I hope somebody can help me in this.

Thank you very much to the whole community and hope to hear from somebody in the near future. I have a deadline and I can not see how I will do this. I am new to labview I am using it only 3 days now.

Kind Regards

Alex

[Dennis_Knutson]

You obviously cannot separate channels before a DAQmx Read since until the read, you have no data separate.

After you read all channels, you can use the Index Array function to get specific channels. Since you did not attach any code, I do not know if you are acquiring a 1D array of waveforms or a 2D array of DBL. So, manipulate the channels you want and place back in the array (Replace Array Element).

Try this and see how far you get. If you get stuck, you need to attach your code.

[Nikolian]

Thank you very much for the response.

All day I was thinking this and this is exactly what I did with the difference that I used at the end a "build array" module to reconnect all the separate channels.

1a) Do you think is better to use the "replace array element" module than the "build array" module?

Also I have problems with the thermolinear module. Is the appropriate module to use to make miliV to Temp. If you look inside the module it says that it needs the voltage to be in microVolt (1000 miliVolt).

1b) Do I need to change my miliVolts to Volts and then put it inside the thermolinear module? Or do I need to change my miliVolts to microVolts and then to the module?Or I can just let them be miliVolts and LabView will do all the work for me using the thermolinear module

2b) Does the Cold Junction Voltage needs to be in miliVolts, microVolts or Volts?

I still can not make the whole system to work but I know I am in the right path

Thank you and hope to have again some of you knowledge 😛

Alex

[Nikolian]

Sorry for the second post

I am using 1D array of waveforms.

thank you

[Dennis_Knutson]

If you are modifying all channels, then it is appropriate to use the Build Array.

I am not familiar with anything called a thermolinear module, sorry.

[Nikolian]

Could you explain me a little about the clock I am using.

I have put rate 1000 but I don't have any idea what to put in samples per channel

I read somewhere that samples per channel should be 10% or the rate so that you don't overflow the buffer.