
HVG-2020A Instruction Manual
Page 13 of 29
Push-button Operation
On top of the HVG-2020A instrument, there is a push-button that serves to
reset the zero by pressing and holding it for at least 3 seconds when the
pressure is known to be well below 0.1 Torr.
For HVG-2020A instruments without a display, the push-button has an
additional function. To toggle RS232 and RS485 communications, press and
hold the button before applying power, then apply power and continue holding button until both LEDs blink
rapidly.
LED Operation
The HVG-2020A will go through an internal self-check upon power up and go into normal operation. The LEDs
on top of the unit indicate the state of the device as follows:
System State
Status LED
Vacuum LED
Pressure > 1000 Torr
Steady Green
Flash Yellow at 1 sec rate
Pressure > 800 Torr
Steady Green
Steady Yellow
Pressure near 760 Torr
Steady Green
Steady Green
Pressure < 700 Torr
Steady Green
Flash Green at 1 sec rate,
Duty cycle proportional to pressure
Pressure < 2 Torr
Steady Green
Flash green at 2 sec rate
Main Board Comm Error
Steady Red
Flash Red at 1 sec sate
Piezo Sensor Failure
Flash Red at 1/8 Sec Rate,
Opposite of Vacuum LED
Flash Red at 1/8 sec rate,
Opposite of Status LED
Calibrate Mode
Flash Green at 1 Sec Rate,
In Synch with Vacuum LED
Flash Green at 1 sec rate,
In Synch with Status LED
Toggle RS-232/485
Flash Green at 1/8 Sec Rate,
Opposite of Vacuum LED
Flash Green at 1/8 sec rate,
Opposite of Status LED
Push-button Force zero
Flash Green at 1/8 Sec Rate,
In Synch with Vacuum LED
Flash Green at 1/8 Sec Rate,
In Synch with Status LED
Push-button Adjust Zero
Steady Green
Flash Green at 1/8 Sec Rate