Is there a limitation on how many thermocouples you can log using SignalExpress 2012 at certain temps?

[sonjay03]

I am running SignalExpress 2012 with a cDAQ-9174 and a NI 9219 Module. I have three K type Thermocouples wired into the module. I am recording temperatures on  three different hot surfaces. I was using Ch 0,1,and 2 when I realized that Ch 1 only displays room temperature while others climb to temperatures of 350 C. I replaced the TC in ch 1 twice. I finally changed it to channel three and it is still doing the same thing.

[DFGray]

The full version of SignalExpress can log hundreds of channels simultaneously, so something else is going on.  Could you please post your project so we can take a look?  In the meantime, a few questions:

1. Do you get the proper values if you use MAX to monitor the thermocouples?  If not, you have a hardware or setup error, most likely a short or open connection.
2. What version of SignalExpress are you using?
3. Is your DAQ version up to date?

[sonjay03]

1. When using MAX all 3 thermocouples have values within 1.2 C of each other.

2. I am using SignalExpress 2012 6.0.0.

3. Most likely not. I took over the equipment from a previous engineer.

[Erik-S]

What version of DAQmx are you using? If you can, try to upgrade to 9.7. A lot of times that can fix any bugs that you may be dealing with.

http://joule.ni.com/nidu/cds/view/p/id/3811/lang/en

-Erik

[Ingenjör_Hansson]

Try to verify that there is no problem with the TC's.

Test all three sensors one by one in Ch.0
Then you test any one of the sensors in one channel at the time 0-3.

Perform the test when the TC is at a hot surface, if you get the same or similar reading with all sensors and all channels there is something very odd with the behavior.

I do believe you'll find some deviation in the hardware (i.e. one sensor or one channel is "broken")

//Ingenjör Hansson