INSTALLATION
Series 642
36/113
Edition 2017-11-24
605593EC
4.6.6
ZERO
ZERO allows for the compensation of the sensor offset voltage.
When ZERO is performed the current value at the sensor input is equated to pressure zero. In case of a 2
sensor system both sensor inputs will be adjusted. A max. offset voltage of +/- 1.4 V can be
compensated. The offset value can be read via local and remote operation.
Local operation:
(‘Control Performance Analyzer’ or ‘Service Box 2‘)
Remote operation:
(Refer to chapter «Explicit messaging control
commands» resp. «Explicit messaging setup
commands» for details)
With CPA:
•
Do the ZERO in menu ‘Sensor / Zero’.
With SB2:
•
Go to menu ‘Zero / ZERO’ and follow
instructions.
1. Send EXECUTING
(if not yet selected)
2. Select SETPOINT TYPE
= position control
3. Select CONTROL MODE for position
= open valve
4. Wait until process chamber is evacuated
and sensor signal is not shifting anymore.
5. Send ZERO
•
Do not perform ZERO as long as pressure gauge voltage is shifting otherwise
incorrect pressure reading is the result. Refer to manual of sensor manufacturer for
warm up time.
•
Do not perform ZERO, if the base pressure of your vacuum system is higher than
1‰ of sensor full scale. We recommend disabling ZERO function in this case; refer
to «Valve and sensor configuration» of the setup procedure. Otherwise incorrect
pressure reading is the result.
