Cold junction compensation

Hello
We have just bought a new NI card (PCI-6052E) connected to a terminal block
(CB-68LP), and so we now have to set-up the cold junction compensation
manually (previously we were using a SCXI-1303 which had it built in).
I would just like to check that the method which we have devised will work.
We are proposing to acquire a thermistor (with known temperature versus
resistance behaviour) and put this in series with a resistor. We would then
put a voltage across these two components and have the voltage drop across
the thermistor as one of the inputs on the terminal block. In the
Measurement and Automation explorer we will set up this channel(called
"cjc") as being a voltage input and tick the box which says it is a
temperat
ure input. We then apply a scaling equation which converts this
voltage into temperature.
We then set up our thermocouple channels in the Measurement and Automation
explorer, and in the CJC source box we say it is user-supplied and make the
user cjc channel the one we made earlier ("cjc").
Is this the correct method of doing this?
Thanks!
Jon Atkinson

Hi Jon -
I'll leave the details of the software to those more familiar with
them. I will offer a bit of comment re. the thermister.
Be a little careful with the thermistor approach. Thermistors suffer
from self-heating problems so the value of resistor chosen is important
to limit these effect.
For a few cents more, it might be worth investigating any of the IC
devices that supply a current or voltage proportional to temperature.
There are also dedicated three terminal cold junction ICs that can be
wired-in fairly simply.
Sincerely,
John
"Dr Jon Atkinson" wrote:
> Hello
>
> We have just bought a new NI card (PCI-6052E) connected to a terminal
block
> (CB-68LP), and so we now have to set-up the cold junction compensation
> manually
(previously we were using a SCXI-1303 which had it built in).
>
> I would just like to check that the method which we have devised will
work.
> We are proposing to acquire a thermistor (with known temperature
versus
> resistance behaviour) and put this in series with a resistor. We
would then
> put a voltage across these two components and have the voltage drop
across
> the thermistor as one of the inputs on the terminal block. In the
> Measurement and Automation explorer we will set up this channel(called
> "cjc") as being a voltage input and tick the box which says it is a
> temperature input. We then apply a scaling equation which converts
this
> voltage into temperature.
>
> We then set up our thermocouple channels in the Measurement and
Automation
> explorer, and in the CJC source box we say it is user-supplied and
make the
> user cjc channel the one we made earlier ("cjc").
>
> Is this the correct method of doing this?
>
> Thanks!
>
> Jon Atkinson
>
>
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Similar Messages

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    Solved!
    Go to Solution.

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  • Usb-tc01 cold junction noise?

    Hello,
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    On Apr 21, 7:27 pm, hrh1818 <[email protected]> wrote:
    > On Apr 21, 2:10 pm, randyram <[email protected]> wrote:
    >
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    > > I would like to use another thermacouple outside of the chamber as reference for the thermacouple that is inside of the chamer. I understand that the reference might drift a bit depending on the room temp, but at least it will be better than not using it.
    > > &nbsp;
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    > > &nbsp;
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    > > &nbsp;
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    "Rabi B" wrote in message
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    >
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  • How to configure a shell and tube heat exchanger with Lab VIew to get data

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