SCXI-1102 multiple TC problem

[deadstick]

Infrequent user here (unfortunately). Our lab has a setup like this:

SCXI-1303 -> SCXI-1102 -> SCXI-1000 -> NI-6251 -> laptop.

We've been running a student experiment for some time that uses a single thermocouple wired to channel a0, and I'm trying to expand it to multiple TC 's. I wired a second TC to channel a1, created a suitable task in NIMAX,  and started it running in continuous sample mode.

The result was a two-trace chart as expected, but both traces indicated the temperature on the first TC. Applying heat to TC0 caused both traces to go up; applying heat to TC1 had no effect.

However, if I create a task using either one of the TC's, its single trace responds normally to heat application.

I tried several other combinations of channel connections, and the behavior is the same: the temp reading of one channel dominates the other in two-TC mode.

Suggestions? TIA...

rj

[nyc_(is_out_of_here)]

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@deadstick wrote:

Infrequent user here (unfortunately). Our lab has a setup like this:

SCXI-1303 -> SCXI-1102 -> SCXI-1000 -> NI-6251 -> laptop.

rj

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What are those?

[deadstick]

SCXI-1303 terminal block

SCXI-1102 thermocouple module

SCXI-1000 chassis

NI-6251 mass term

Is this not the right subforum?

rj

[nyc_(is_out_of_here)]

It sounds like a Task may not be configured properly in NI-MAX.

[deadstick]

OK, here's a copy of the task. This one is set up to use channels ai2 and ai4, and the channel that dominates the chart in this case is ai2.

[nyc_(is_out_of_here)]

You wrote in your first post that you were using channels ai0 and ai1.

Where did ai2 and ai4 come into the picture?

Anyway, you have some other things and devices going on in that config file I don't quite understand.

I would suggest simplifying to just the thermocouples.

In addition, if you have a USB 6251, I don't understand the SCXI stuff.

[deadstick]

I tried several other combinations of channels to see if they made a difference, but they didn't. Channels ai2 and ai4 act just the way ai0 and ai1 did.

The NI-6251 is simply interfacing the SCXI chassis to the laptop, replacing the PCMCIA card we used to use when our laptop was an XP machine.

What are the "other things" you mention? The chassis also has a strain gage module in it, but nothing other than the thermocouples is connected to the SCXI-1303.

[nyc_(is_out_of_here)]

You should be able to connect to the USB-6251 directly. I don't understand the purpose of the SCXI equipment.

The USB-6251 has 16 analog inputs http://sine.ni.com/nips/cds/view/p/lang/en/nid/202802

[Mr_Engineer]

Do not use NI 6251. Instead connect output of 1600 module direct to usb port of laptop. Use Ain0 and Ain1.

Regards

Jamal

[nyc_(is_out_of_here)]

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@Jamal_IE wrote:

Do not use NI 6251. Instead connect output of 1600 module direct to usb port of laptop. Use Ain0 and Ain1.

Regards

Jamal

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Where does he write that he has a "1600 module" ?