MKS 937B Operation Manual
72
1 Buffered Aout A1 11 Log/Lin Aout C1
2 Buffered Aout A2 12 Log/Lin Aout C2
3 Buffered Aout B1 13 Combination Aout 1
4 Buffered Aout B2 14 Combination Aout 2
5 Buffered Aout C1 15 Power A1
6 Buffered Aout C2 16 Power A2/Degas A1
7 Log/Lin Aout A1 17 Power B1
8 Log/Lin Aout A2 18 Power B2/Degas B1
9 Log/Lin Aout B1 19 Power C1
10 Log/Lin Aout B2 20 Power C2/Degas C1
21 to 37 Ground
Table 8-2 Pin out for 937B analog output.
8.3 Buffered analog output
A buffered analog signal responds immediately to sensor signal changes; it can therefore be used in
critical fast controlling applications.
Buffered analog signals are non-linear and strongly sensor dependent, use
these signals with due caution.
Normal buffered output for the 937B is 0 to 10 V. If a negative buffered voltage is observed, it may be
caused by
No discharge for a cold cathode, or a pressure reading of less than 1x10
-11
torr.
Areading below zero for a capacitance manometer (zero adjustment may be required).
The buffered analog outputs for variety of pressure sensors in an unpowered state are shown in
Table 8-3.
Sensor Buffered Analog Output when power is off
Cold Cathode (CC) > 10 V
Hot Cathode (HC) > 10V
Pirani (PR) 0
Convection Pirani (CP) 0
Table 8-3 Buffered analog output when sensor power is off.
A hot cathode gauge uses different emission currents in different pressure ranges and therefore the
analog output depends on the emission current and pressure. To avoid problems, logarithmic analog
output is used as the buffered analog output.
Buffered analog output for the cold cathode, hot cathode, Pirani, convection Pirani and capacitance
manometers are shown in following figures and tables.
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