Agilent Technologies Turbo-V 750 TwisTorr Mode D'emploi page 347

Figure 47
The set point output stays at 0 Vdc until the frequency becomes
higher than 505 Hz (that is 500 Hz + 1 % of 500 Hz), then the output
goes at 24 Vdc and stays at 24 Vdc until the frequency becomes lower
than 495 Hz (that is 500 Hz – 1 % of 500 Hz).
It is possible to delay the set point checking for a programmable
delay time.
The PROGRAMMABLE SET POINT signal has the following default
settings:
PURGE/VENT VALVES: the Turbo-V 750/850 TwisTorr Pumping
System can integrate the Purge and Vent valves. The two valves are
Normally Closed (N.C.) so if a power fail occurs, the valves will
remain closed.
The valves operating mode can be set only by serial line with WIN
125, WIN 122 and WIN 145 (see following diagram for details).
Turbo-V 750/850 TwisTorr User Manual / 87-901-020-01
reference quantity: frequency
threshold: 742 Hz
hysteresis: 2 %
activation type: high level
delay time: 0 second
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