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## Custom Scale for Ion Gauge HELP

I have a Kurt J Lesker 354 ion vacuum gauge that puts out an analog 0-9v representing vacuum pressure in Torr.

I'm having trouble getting the custom scaling to work. I have been trying to use the DAQ assistant custom polynomial scale since I need logarithmic scaling.

The KJL354 manual gives the analog output (log-linear 0 to 9 Vdc,1 volt per decade)

Pressure Torr                    Voltage

1.0E-10                               0.0

1.0E-09                               1.0

1.0E-08                               2.0

1.0E-07                               3.0

1.0E-06                               4.0

1.0E-05                               5.0

1.0E-04                               6.0

1.0E-03                               7.0

1.0E-02                               8.0

5.0E-02                               8.698

As you can see, the highest vacuum at 1^(-10), is zero volts and every volt represents a magnitude of ten as the vacuum pressure decreases to 5^(-2)

since these are negative values inverse of the voltage, I put polynomial scale coefficients at:

Order       Coefficient

a0                    1

+x*a1            10

+x^2*a2          9

+x^3*a3          8

+x^4*a4          7

+x^5*a5          6

+x^6*a6          5

+x^7*a7          4

+x^8*a8          3

+x^9*a9          2

+x^10*a10     1

The scale ends up upside down and representing a small range of exponents, whether I put the coefficients ascending or descending.

I have the pre-scale selected as volts. from what I understand each volt would be the coefficient of x.

Any Help would be apprecieted.

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## Re: Custom Scale for Ion Gauge HELP

The manual is here.  Look on page 32 of the pdf and it shows the conversion formulae.  (Hey, I'm not going to do ALL the legwork for you.)  😉

Bill

(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.
Humble author of the CLAD Nugget.
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Accepted by Subquantum369

## Re: Custom Scale for Ion Gauge HELP

@billko wrote:

The manual is here.  Look on page 32 of the pdf and it shows the conversion formulae.  (Hey, I'm not going to do ALL the legwork for you.)  😉

I Don't know why not?

"Should be" isn't "Is" -Jay
Message 3 of 6
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## Re: Custom Scale for Ion Gauge HELP

@JÞB wrote:

@billko wrote:

The manual is here.  Look on page 32 of the pdf and it shows the conversion formulae.  (Hey, I'm not going to do ALL the legwork for you.)  😉

I Don't know why not?

LOL it was more an exercise about how to go about finding information.  😉

You know, all that good stuff about teaching a man to fish, etc, etc...

Bill

(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.
Humble author of the CLAD Nugget.
Message 4 of 6
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## Re: Custom Scale for Ion Gauge HELP

Thanks for the help!

I thought I could do it from the custom scale in DAQ Assistant, but your solution makes more sense.

Message 5 of 6
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## Re: Custom Scale for Ion Gauge HELP

@Subquantum369 wrote:

Thanks for the help!

I thought I could do it from the custom scale in DAQ Assistant, but your solution makes more sense.

I don't even want to think about how many times I overcomplicated something and someone else just comes along and says, "Why not just do it this way?"  😉

Bill

(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.
Humble author of the CLAD Nugget.
Message 6 of 6
(1,359 Views)