Do More with Your NI USB-TC01

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Using the USB-TC01

Hello

I've come across the USB-TC01 device whilst searching on google for a new temperature probe and have a few questions.  I have no experience of National Instruments at all, so whilst these may sound like noob questions, please bear with me.

I have an existing PDA application written for the .net compact framework designed specifically to run on both X86 and ARM platforms for most handheld units. Previously we have used a serial interface to a temperature probe but we are now investigating USB. The primary function of the application is to collect data for water assets and take relevant temperatures for each asset. Note: This is not a "logger" type application where regular temperatures are required but a "sampling" type where a single instance of a temperature is taken and stored. We may also want to take multiple temperature types for a single asset i.e. Hot, Cold, Ambient, etc.

My questions about this device are.

Can I get a temperature directly from the device without using LabView? Is there an API is supports/supported by  the .net compact framework?

Can the device be used just to record a single temperature i.e. request sent from application to read temperature, device returns the curent temperature.

Is there any delay between the probe reading the temperature and the transmission to the pda. i.e. is it logged first then sent or does a request interrogate the probe directly and return the temperature at that instant.

Does a change of probe require the device to be reset. I.e. if I take a temperatre with a wire probe and then change to a contact probe, does the device need a control reset or will it read using the new probe (Assume they will both by K-Type)

Thanks in advance for any help

Andie

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Re: Using the USB-TC01

Hi Andie-

I'll try to help with your questions individually:

1.  Yes, there is non-LabVIEW support available.  Specifically, there are C/C++, CVI, and .NET APIs available with the supplied NI-DAQmx driver.  The catch is that NI-DAQmx only supports Windows XP, Windows Vista, and Windows 7.  Since you mention PDA and ARM/x86 platforms, I'll assume you are using a different operating system environment.  If my assumption is correct, you may need to consider developing your own driver support which is better provided by the USB-2001-TC, provided by MCC ( http://www.mccdaq.com/usb-data-acquisition/usb-2001-tc.aspx ).

2.  Yes, in fact, the device can only return single temperature readings on demand.  There is no buffering on the device for temperature readings.

3.  The only delay in transmission is due to latencies in transferring data from the onboard ADC to the microcontroller that runs the device and then from that microcontroller over USB to the computer.  The ADC->uC latency is negligible compared to USB latency which would require ~2 USB frames to initiate and then transfer the reading from the ADC.  This is probably more information than you're looking for; it suffices to say that there is very little latency and no buffering or artificial delay in the data path back to the host.

4.  No, changing connections or probe types does not require any hardware reset.  You might need to react to the change in software (for example, if the TC type changes), but there are no explicit restrictions to reinitialize the hardware or anything like that.

Hopefully this helps-

Tom W

NI

Tom W
National Instruments
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Re: Using the USB-TC01

Thanks very much for taking the time to answer these questions. 

Your assumption in answer 1 is correct. The Target O/Ss are Windows Mobile 5+ and Windows CE.  It looks as though the MCC product may give us the solution we require.  Thanks for the link

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Re: Using the USB-TC01

Hello,

     I work on USB-TC01 and i wanted to find sample code to get temperature from this device in c# .net 2.0. I didn't find it in sample code of NiDaqmx 9.1

Thanks

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Re: Using the USB-TC01

We have an example on our website you can use with the USB-TC01:

NI-DAQmx: Continuous Acquisition Thermocouple Samples - Software Timed in .NET

For the USB-TC01 you can leave all the defaults the same except you need to set CJC Source to Internal.

Kristen
National Instruments
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Re: Using the USB-TC01

Thank you, it works. I just wanted to know what does the value means ? How can i convert it in celcius ?

Ex :1290.28822967463

Regards 

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Re: Using the USB-TC01

The value should already be in Celsius.  You may also need to change the Thermocouple Type setting to the type you are using.  Does doing that help?

Kristen
National Instruments
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Re: Using the USB-TC01

Thank you it was the internal value. I put a K thermocouple and it works.

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Re: Using the USB-TC01

I also just got the usb-tc01, but i don't have labview. Is it possible to use this with Excel (via VBA)? If so, are sample codes available?

Schrev_t, is visual studio required to use .net code? (sorry about the newbiw questions. I have zero programming knowledge, except for old basic).

Thanks in advance.

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Re: Using the USB-TC01

hellomoto,

If you know how to call a C dll from VBA you can use the DAQmx C API with your USB-TC01.  You'll need to download and install the latest DAQmx driver.  Make sure when you install it that you select "ANSI C Support" from the feature tree. 

I only found one example that was specifically about calling DAQmx from Excel:

NI-DAQmx: Performing Digital I/O in Excel

We have a number of examples for using DAQmx with Visual Basic 6, which from what I understand is similar:

NI-DAQmx Examples for Visual Basic 6.0

We may not have an example specifically for reading Temperature values but there will be a DAQmx C Reference that will be installed to your Start menu to help you.

We have a lot more examples for using DAQmx in .NET than we do for Visual Basic 6, so .NET may be the easier way to go.

Microsoft has a free version of Visual Studio called Visual Studio Express Edition.  I'm not sure what the limitations are for it, but if you are interested in learning .NET they say it's a good place to start.  There's more information about it on Microsoft's website:

http://www.microsoft.com/express/Windows/

Kristen
National Instruments
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