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Instruction Manual
Analog Output
7
The CVM201 provides either a non-linear or a
log-linear analog output. Additionally it can provide
a linear 0-10 Vdc analog output.
Non-Linear Output
The first Convectron® gauge controllers produced a non-
linear output signal of 0.375 to 5.659 Vdc for 0 to 1000
Torr of N
, roughly in the shape of an "S" curve, as shown
2
at right. Granville-Phillips® adopted the same output
curve for most of their Mini-Convectron® modules and
controllers with non-linear output (although in recent
years, some Granville-Phillips® controllers may output
variations of the original S-curve).
The non-linear output from InstruTech convection
gauges, modules and controllers duplicates the original
S-curve of 0.375 to 5.659 Vdc for 0 to 1000 Torr.
The tables shown in
section 7.1
lookup data for converting the non-linear output voltage
into pressure values for nitrogen and various other gases.
Log-Linear Output
Many InstruTech modules and controllers also provide a
log-linear output signal, as an alternative to the non-
linear signal described above. This output, shown at
right, is a 1 Volt per decade signal that may be easier to
use for data logging or control.
The table shown in
section 7.3
data and provides the formulas for converting the
log-linear output voltage into pressure values for
nitrogen and various other gases.
Linear 0-10 Vdc Analog Output
The CVM201 also provides a linear 0-10 Vdc analog output. The linear output voltage can be any value between 10
mV and 10 V corresponding to displayed pressure between 1 mTorr and 1000 Torr. However, the useful range of the
linear analog output is three decades. For example if the minimum pressure selected is 1 mTorr (1.0 x 10
a corresponding minimum voltage output of 0.01 volts, then maximum pressure selected to correspond to a
maximum voltage output of 10 volts should not exceed 1.0 Torr. If your application requires the analog output to
cover a pressure range exceeding three decades then consider using the non-linear or the log-linear analog output.
Note that an analog output of less than 0.01 volts (to near 0 volt) may indicate a damaged or faulty sensor.
InstruTech, Inc.
and
7.2
contain the
and
7.4
contain the lookup
Non-Linear Analog Output
Non-Linear Analog Output
6
6
6
Output - Volts
Output - Volts
Output - Volts
5
5
5
4
4
4
3
3
3
2
2
2
1
1
1
-3
-3
-3
-2
-2
-2
-1
-1
-1
10
10
10
10
10
10
10
10
10
10
10
10
Log-Linear Analog Output
Log-Linear Analog Output
8
8
7
7
Output - Volts
Output - Volts
6
6
5
5
4
4
3
3
2
2
Pressure - Torr
Pressure - Torr
1
1
-3
-3
-2
-2
-1
-1
10
10
10
10
10
10
10
10
CVM201 Super Bee
Pressure - Torr
Pressure - Torr
Pressure - Torr
0
0
0
+1
+1
+1
+2
+2
+2
+3
+3
+3
10
10
10
10
10
10
10
10
10
0
0
+1
+1
+2
+2
+3
+3
10
10
10
10
10
10
-3
Torr) with
Page 18
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