Suitable device for thermocouple data acquisition simultaneous to USB 6210/6212 DAQ

[Jarir]

Hi,

I have USB 6210 and 6212 DAQs for analog voltage reading from sensors. Now I want to read temperature(Accuracy +/- 0.5C) simultaneous to the analog voltage reading by extending my existing LabVIEW code.

Recently, I have found out that I can not use K type TC directly to my DAQ. I need a separate signal conditioning circuit. I am not good at electronics, therefore I am looking for easy way out ideas for this application. 

I am thinking of using thermocouple analog conditioning interface(https://www.digikey.com/en/products/detail/playing-with-fusion-inc/FDQ-10001-K/13998047?s=N4IgTCBcDa...) to use. As far as I understand, I can connect the K type thermocouples here and get the analog data to USB daqs, then calibrate the data according to the equation to get the temperature(Celsius data). Am I going into the right direction?

Do you have any more suggestions for devices that will make my life easy considering the application? My budget is around $500.

[santo_13 · Accepted solution]

How many TCs? If your budget is $500, you may be able to get another DAQ that directly supports TC reading.

https://www.ni.com/en-us/shop/model/usb-tc01.html

If you want to get a +/-0.5C accuracy, have you attempted to calculate your overall accuracy, resolution of the setup with DAQ 621x with the Thermocouple signal conditioner?

The more stages in the signal chain, the more the sources of error.

[Jarir]

I need one TC initially, later I might increase it to 2. 

I checked TC01. It should work for me the best. However, I am concerned that if I can use the TC01 and USB 6210 simultaneously on one PC. Because, previously, I tried to connect USB 6210 and 6212, it did not let me because it said this DAQ doesnot support multi device data acquisition. 

Could you please shade more light on that?

[santo_13]

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@Jarir wrote:

I need one TC initially, later I might increase it to 2. 

I checked TC01. It should work for me the best. However, I am concerned that if I can use the TC01 and USB 6210 simultaneously on one PC. Because, previously, I tried to connect USB 6210 and 6212, it did not let me because it said this DAQ doesnot support multi device data acquisition. 

Could you please shade more light on that?

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Correction, you can use as many DAQ devices as possible at the same time but not on the same task since they are separate USB comm ports.

You can use 6210 and 6212 simultaneously, just that non in the same Task.

[Jarir]

I am sorry if I am asking too silly question(Lack of experience). How can I create different tasks? Do you mean having two different code for acquiring from two DAQs? Could you please elaborate?

I attached a code that I use to collect from 4 channels. For example, I want to collect 2 channels from NI USB 6210 and 2 channels from 6212(or may be one from TC01) with a same timestamp. Can I do that? 

[rolfk · Accepted solution]

A DAQmx Task is a resource that contains one or more channels to operate on. For higher end hardware such as PXI it is often possible to combine channels from different devices in one single task but for USB devices this is not an option since there is no communication between the two devices directly that would let them synchronize the channels to the same clock.

In your VI you use a task for your physical channel, where you can specify one channel "Dev1/ai0" but it is also possible to specify a range of channels "Dev1/ai0:3" or add multiple DAQmx Create Channel VIs to configure different channels with different configuration on the same task.

It's  also totally valid to have multiple tasks in the same application as long as they do not try to use shared resources such as clocks or analog digital converters at the same time.

So you could not have one task using "Dev1/ai0" and another one using "Dev1/ai1" since these channels are on the same device and can't be operated in parallel. But you can have one task using "Dev1/ai0:ai3" and another task using "Dev2/ai0" with Dev1 being your 6210 and Dev2 being your 6212.

[Jarir]

Ok, I guess I have better idea now. I just need to create separate tasks for separate DAQs in my code. Could you refer me to some sample programming available on LabVIEW? or any keywords that I should search?

Additionally, by this way, can I get simultaneous data from USB 6212 and TC01?

[santo_13]

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@Jarir wrote:

Ok, I guess I have better idea now. I just need to create separate tasks for separate DAQs in my code. Could you refer me to some sample programming available on LabVIEW? or any keywords that I should search?

Additionally, by this way, can I get simultaneous data from USB 6212 and TC01?

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Simultaneous - yes

Synchronous - no (may be possible to sync 6210 and 6212 with externally wired triggers)

[SteveD123]

You state you want accuracy to ±0.5°C.

Over what temperature range do you require this?

You are aware that you are up against the basic accuracy possible with a type k? https://www.thermocoupleinfo.com/thermocouple-accuracies.htm gives Standard accuracy as ±2.20°C or ±0.75%, and special order accuracy as ±1.10°C or ±0.4%.. This is because of impurities in the wire used to make them.

Also aging will become a concern above 316°C. You may wish to consider type N or even type R.