Measure voltage and temperature from one daq card

[JimK247]

Hi,

I am using a 9211 DAQ card on USB 9162 to measure the heat flux.

A heat flux gauge outputs voltage for heat flux and temperature (Type T) at the same time.

So it has 4 wires (2 for heat flux and 2 for temperature) and I connect 2 wires to channel 2 and the other 2 wires to channel 3.

The labview code measured the temperature and voltage but not at the same time.

When the temperature is recorded, the voltage becomes 0 and vice versa. (Err 50103)

Is it not possible to measure temperature and voltage from a single DAQ card?

Thank you.

[GerdW]

Hi Jim,

put both channels into just one DAQmx task to read them both at the "same" time…

I hope you are using plain DAQmx functions and not that dreaded DAQAssistent ExpressVI, do you?

[JimK247]

Hi GerdW,

Thank you for the reply.

I attached my code.

The channel2 is thermocouple of heat flux gage and the channel3 is voltage from the heat flux gage.

I found no mistake in the code.

Could you let me know what is the problem?

Thank you.

[GerdW · Accepted solution]

Hi Jim,

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@JimK247 wrote:

I found no mistake in the code.

Could you let me know what is the problem?

---

You found no problem, even though I wrote the possible solution in my previous post:

Place both channels into one DAQmx task!

Most DAQ devices use only one ADC for several input channels and you cannot share this single ADC between several (DAQmx) tasks. You need to read all channels within one DAQmx task…

Like this:

Why did you use the "N channels" when your tasks only contained one channel each?

Why do you fiddle with "wait time" when you could use DAQmxTiming instead?

Why was there a coercion dot at WaitTime?

[JimK247]

Hi GerdW,

I just couldn't understand your instruction at first.

But now I fully understand and modified the code.

The code can read and output all data properly.

Thank you for the advice!