Agilent Technologies Turbo-V 750 TwisTorr User Manual page 344

17 Technical Information
Interconnections
The duty cycle percentage is referred to the low level portion of the PWM signal
NOTE
High Speed is the nominal rotational frequency of the pump (825 Hz). Low
NOTE
Speed (350 Hz) corre-sponds to the rotational frequency for a stand by status.
Users can set rotational frequency between these two values.
If any signal isn't applied (no connection) the driving frequency is set
to "Maximum ROTATIONAL frequency" (the default value is 825 Hz;
it is settable via serial line by means of window 121: see the serial
command table).
If a continuous signal is applied (pin 5 connected to pin 9) the
driving frequency is set to "Low Speed" (the default value is 350 Hz;
it is settable via serial line by means of window 117: see the serial
command table).
The "Low Speed" function can also be activated by serial line with
win.001, and the low speed value can be adjusted via serial command
win.117.
Both low speed value (win.117) and high-speed value (win.120) are
limited between 350 Hz (can't be set by the user) and "Maximum
excitation frequency" (win.121, 825 Hz default).
SOFT START: input signal to activate the soft start function. This
function must be activated (pin-7 shorted with pin-9) if the pump
remains unused for a protracted stop, and deactivated for the next
run-up. See the paragraph "SOFT START" for a more detailed
description.
PROGRAMMABLE ANALOG SIGNAL: this output signal is a voltage
(from 0 to 10 Vdc, max load 1.5 mA) proportional to a reference
quantity (frequency or power) set by the user. The default setting is
the frequency (see the following example diagram).
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