MKS 651D Series, Руководство пользователя, Страница: 40 / 162

Set Points Chapter Three: Overview
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Set Points
The 651 controller has five internal set points (A to E) and is capable of accepting one analog set
point through the Interface connector on the rear panel. The unit controls the system based on
the value of the “active” set point; only one set point can be active at a time. LEDs on the front
panel indicate which internal set point is active. There is no LED to indicate that the system is
under analog set point control (in fact, all LEDs on the front panel go out).
You can configure the 651 controller so that an internal set point is configured to represent a
pressure or position. Pressure set points are reported in user-defined units of Torr, mTorr,
mBar, µBar, Pascal, or kPa. Position set points are reported as a percentage of open.
The analog set point can be configured for 5 Volt or 10 Volt full scale input. The analog set
point value is expressed as a percentage of full scale, using the following formula:
A
NALOG
S
ET
P
OINT
= (A
NALOG
S
ET
P
OINT
V
OLTAGE
/ F
ULL
S
CALE
V
OLTAGE
)
You can also operate the analog set point at a different full scale input, for example 4.5 Volts, by
recalibrating the full scale of the analog set point. Refer to
How To Calibrate the Full Scale of
the Analog Set Point , page 72 (Local operation), or Chapter 5 Remote RS-232 Operation on
page 75 for more information.
Softstart Rates
The softstart feature is used to define the rate at which a control valve initially moves toward a
new set point. The rate is given as a percent of full
speed and can be used on either a pressure
or position set point. Softstart control can be applied to all of the set points, as well as the valve
open, and valve close commands. Once set point is achieved under softstart control, the valve is
free to move at full speed.