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7.
Analog Output
7.1
Description
7.1.1
The MX7B provides the option for outputting the pressure reading in an analog form. Operators
who wish to use PLCs to monitor processes should find this function useful. There are three
different analog output formats to choose between. The formats include Logarithmic, Linear by
Decade, and Linear.
7.2
Linear
7.2.1
The Linear output covers a select range of the MX7B with a linear scale. The 10 Volt or full-scale
value of the output can be selected from the following values: 1*10
−
5
Torr, 1*10
−
4
Torr, or 1*10
−
3
Torr. The scale extends three decades below the full-scale value. Three decades below the 10 V
value is the 0 V value. This corresponds to the low end of the range and output below the 0 V
value is not available. For a wider range use a different analog output format. Note that only the
10 V exponent is selectable. When navigating through the menu, the 0 V exponent will be
viewable but not settable. Use the high value (1.0*10
H
) exponent H in the following equation to
convert the voltage output to pressure:
𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉
𝑂𝑂𝑂𝑂𝑉𝑉𝑂𝑂𝑂𝑂𝑉𝑉
× 10
𝐻𝐻−1
=
𝑃𝑃𝑃𝑃𝑉𝑉𝑃𝑃𝑃𝑃𝑂𝑂𝑃𝑃𝑉𝑉
7.2.2
To select the Linear output, navigate to the Analog Output screen, press ENT, and then use the
UP or DOWN arrow to select Linear. Press ENT to save the change. Then press DOWN once to
navigate to the Output High screen. Press ENT to unlock the screen and press UP or DOWN to
select the full-scale pressure for the analog output.
7.3
Linear by Decade
7.3.1
The Linear by Decade output spans the entire range of the MX7B. It uses the units digit of the
voltage reading to communicate the decade of the pressure reading and the units after the
decimal to communicate the specific pressure using the very generalized expression below,
where A, B, C, and D are digits ranging from 0-9:
𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉
=
𝐴𝐴
.
𝐵𝐵𝐵𝐵𝐵𝐵
→ 𝑃𝑃𝑃𝑃𝑉𝑉𝑃𝑃𝑃𝑃𝑂𝑂𝑃𝑃𝑉𝑉
(
𝑇𝑇𝑉𝑉𝑃𝑃𝑃𝑃
)
−
10
𝐴𝐴−11
∗
.
𝐵𝐵𝐵𝐵𝐵𝐵
7.3.2
For example, a voltage reading of 8.367 Volts corresponds to a pressure of 3.67*10
−
4
Torr.
10
8−11
∗
.367
−
10
−3
∗
.367
∗
10
−4
𝑇𝑇𝑉𝑉𝑃𝑃𝑃𝑃
7.3.3
To select the Linear by Decade output, navigate to the Analog Output screen, press ENT, and
then use the UP or DOWN arrow to select Linear by Decade. Press ENT to save the change.
