How can I get the program to recognize two different types of thermocouples?

Question

I am using a PCI-4351 card with a TBX-68T terminal block. I was having trouble writing and finding a program that would give me more than one reading/sec. I found a program on the NI website called "435x_logger_triggering", and so far it is the only program that I have found that will actually collect data at 60 Hz. Unfortunately, this program only lets you specify one mode for your thermocouples. This is a problem because we are using two thermocouples, one is type K and the other is a type R, so we get bad readings from one of the thermocouples depending on which mode it is set on. I would like to know how I can program in a seperate mode for each channel in this program. Un
fortunately, some of the sub VI's in this program are password protected, so I don't know if this is possible. Everything is entered correctly in the Measurement and Automation explorer, so that isn't the problem. I will attach a copy of the program that I am using. I have modified it slightly from the one I got off the NI website, so that the thermocouple readings have a time stamp and are saved to disk. Any assistance you could give me would be greatly appreciated.
Thanks,
Jordan
Attachments:
Forest_Fire_Thermocouple.vi ‏140 KB
435xlogger_triggering.vi ‏110 KB

Answer 1

Jordan,
You should be able to sample two different thermocouples in the example that ships with the 435x driver called "Getting Started with multiple tranducers Continous". Simply put each type of thermocouple in a different index . Each index of the Transducer Group Array can have a different type and specify the channels that correspond to that type.
One way that you can speed this VI up is to place a wait inside of the while loop. This will reduce the number of times the software polls the card if it has available data(increasing the overhead). I would suggest about 500 ms. The data that you receive will all have the same delta t because the sampling clock is hardware driven not software, so it does matter when the data is polled.
You will not be
able to get 60 samples per second when you are measuring multiple channels anyway. The sample rate for multiple channels is about 9/(# channels). This is explained in the 435x Users Manual.
I looked at your code and noticed that you tried to change some of the enumeration controls. Unfortunately you will not be able to change these because they are password protected on the low level subVIs, which is where they are defined.
The way you select if you want the notch filter is in the 435x Config you specify fast or slow. If it is slow then it will select 10Hz as the nitch filter. If you select fast the it will select either 50 or 60Hz You would then use the function "435x Set power line frequency"
Good luck,
Mike