MKS 943 Series, Инструкция по эксплуатации

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4 Installation
21
Series 943 Cold Cathode Vacuum Sensor
Instruction Manual - #100009887
If both the analog output and the high voltage enable are being used, use separate ground wires for
each and connect them only at the Accessory port. Otherwise, the analog voltage may be incorrect.
4.1.5 Logarithmic Analog Output
Connecting to pins 11 and 12 provides a logarithmically-scaled, pressure dependent voltage V
0
from 1 to 9 V. Pressure P can be calculated using the following equation:
P = 10(V
0
-11)
where,
V
0
is in volts
P is in Torr.
For example, if V
0
= 5 V, then P = 10(
5-11
) = 10
-6
Torr
This output is provided by a microcontroller driving a D/A converter and has a response time
of about 0.25 sec.
4.1.6 Buffered Analog Output
A pressure dependent voltage V
0
with a range of 0 to 9 V is provided on pins 13 and 14. Pressure
can be determined using the graph shown in Figure 4-2 or Figure 4-3.
This output is simply a buffered output of the sensor circuit and has a fast response time of less than
50 msec above 1.0 x 10
-8
Torr.
Notice
Do not inadvertently short circuit the set point relay terminals to the
analog output voltage
.
Table 4-2: Logarithmic Analog Output
If
V
0
=
Then
0V Controller is OFF
0.5V
Display reads LO x 10
-10
Torr
9V
Display reads HI x 10
-2
Torr
9.5V High voltage turned OFF by
protection set point
10V High voltage is OFF