Help configuring Thermocouples in LabView for a Mac

[nickc235]

I am trying to set up a LabView program that will read 4 T-type thermocouples attached to a NI 9211 Thermocouple Input and in a NI USB-9162 Hi-Speed USB Carrier. I had no issues when using a PC to set this up with the DAQ-Mx software, but I need to configure a program on a Mac for a laboratory experiment which can record and display the temperatures read by 4 thermocouples. Since Macs do not have the DAQ Assistant, all the tutorials do not work on how to set up an appropriate program. Similarly, Mac only supports the DAQmx Base software, which I have been unable to get to read more than 1 thermocouple at a time (I need to be able to record and display a graph of the 4 thermocouples simultaneously. I was wondering if anyone could offer any assistance on how to appropriately use LABVIEW 2009 to read the thermocouple temperatures, record their temperatures, and display the 4 temperatures on one graph in real time. Thanks.

[johnsold]

Does DAQmx Base work with the USB-9162? It is not listed under the supported devices.

Please post what you have tried so far.  Perhaps someone can make some suggestions.

Lynn 

[AdnanZ]

What you have over there is the USB-9211A (which consists of a 9211 with a USB-9162 carrier) which should work with DAQmx Base 3.x. Have a look at the link webpages:

DAQmx Base 3.3 - Mac OS X - Readme.rtf

What is the difference between the USB-9211 / USB-9215 and the USB-9211A / USB-9215A?

I am assuming you are using the latest driver. Your exepected behavior is quite right. You need to realize that the DAQmx Base software is NOT multi-threaded which means you will NOT be able to acquire data simultaneously from different channels (which affects the way you program the rest of your application), as you have noticed. That is one huge difference between DAQmx and DAQmx Base. Unfortunately, the only solution is to use a Windows OS.

Message Edited by Adnan Z on 01-21-2010 02:51 PM

[JoeFriedchicken]

I would like to make a clarification about DAQmx Base. Adnan is correct that DAQmx Base is not multi-thread safe, but that limit does not prevent you from acquiring data from more than one channel. Rather, it prevents you from making parallel calls into the driver and forces you to make sequential calls instead. When programming in LabVIEW, make sequential calls by using only one error cluster to connect all of the DAQmx Base calls. You can still have other parallel threads in your VI, but the DAQmx Base calls must all come from the same thread.

Without seeing your code, my guess is that you're trying to create one DAQmx Base task for each thermocouple channel, which won't work since the 9162 only has one timing engine and the first task will reserve it and lock the others out. Try using the example '<LabVIEW root>/examples/daqmxbase/dynamic/ai/Cont Acq&Graph Voltage-Int Clk.vi' and changing the channel string to "Dev1/ai0:3" and see what happens 😉