Problems setting up SCC-TC02 with SCC68

[JGHM]

I have trying to set up a task to read  a J-type thermocouple on a SCC-TC02 in a SCC-68 board connected to a DAQCard 6036E
When I test the task I get vaules for temperature in the 10e9 range!!. Reading the SCC-TC02 manual indicates that the TC voltage is amplified by x100, so the input voltage to the thermocouple polynomial is too high resulting in the abnormally high values (yes I did set the CJC properly).
How can you set the level correctly or must I just read it at as a voltage and do my own thermocouple convrsion (seems a real hassle )?

[Jeff_T.]

JGHM,

You should not need to worry about the amplification, the drivers will look at the read values and scale appropriately.  I have used this device before with J type thermocouples and with the SCC-TC02 and it worked very well.  There are several reasons why you could be getting these readings.

1.) First make sure that the SCC-68 is correctly configured in MAX.  You configure the device by selecting NI-DAQmx Devices > Create New Device > DAQmx SCC Connector Block > SCC-68.  Make sure you have the SCC-TC02 properly selected in the configuration window and make sure you have the correct device selected.

2.) When you make your task, make sure you are using Analog Input > Temperature > Thermocouple and make sure your physical channel is SCC1/Mod1/ai0 and the device type is SCC-TC02.

3.) You already said that your CJC was correctly configured.  I just want to double check that you have pin 70 connected to pin 57 and pin 71 connected to pin 23.  Also make sure you select "built-in" for your CJC source in the temperature task.

4.) Finally (and most importantly) make sure you have wired pin 62 to pin 67.  This connects AI Gnd to AI Sense.  This is required when using SCC modules in this device. 

Please check these points and let me know if you make any progress.  If you continue to have problems feel free to post to this thread and I will try and find something else for you.

Best Regards,

Jeff Tipps
Applications Engineer
National Instruments

[NewUser2007]

I had similar problem, and using the suggestion, I double checked all the connectiong and I am still getting 289°C value using a K type TC.  I know the lab is not that hot!

It had worked at one point, but as I was teting other part of the LabVIEW code, it all of a sudden stopped working and started to give me very strange numbers in the 289 range

any other thoughts?

thanks!

[Mark_E]

Hi NewUser2007,

You said: “It had worked at one point, but as I was teting other part of the LabVIEW code, it all of a sudden stopped working and started to give me very strange numbers in the 289 range.”

Do you mean:

1.       Your code was executing fine and then you get 280°C forever afterward even after stopping and running your code again? or

2.       Running your code gives good results until a certain point every time it’s run?

In other words, did a connection come loose and now you are not receiving the signal properly because of the hardware, or did something change in your software that altered the expected functionality?

For hardware, I would recommend reading through the SCC-68 User Guide. It is a pretty thorough resource for setting up the hardware correctly for your particular hardware.

If you suspect your code to be at fault, try using a shipping example (From LabVIEW, select Help » Find Examples and search for Thermocouple examples).

If you are still having difficulty, please outline your entire setup so that all variables of your system are considered.

Additional resources:

Taking Thermocouple Temperature Measurements tutorial at ni.com/zone