40
Using the Sensor Zero
The [
Z 1
] command corrects for any sensor zero offsets. There is no request associated with this function.
This command will zero the currently selected pressure sensor range.
To use the sensor zero:
1. Turn the gas flow off.
2. Drive the valve to full open by issuing the command:
O
Refer to Driving the Valve to Full Open, page 39.
3. Pump the system down to base pressure.
In order to achieve a proper zero, the pressure of the system must be
lower
than the resolution of the
sensor used to measure system pressure.
4. Enter the command:
Z 1
To remove the sensor zero correction, refer to
Removing the Sensor and Special Zeros
page 40
.
Note
If the pressure reading (at base pressure) is greater than 4% of full range, the sensor will not
be zeroed.
Using the Special Zero
The [
Z 2 value
] special zero command zeros the base pressure in systems where the known base pressure is
not
at
, but
near
zero (as measured by another transducer in the system). There is no request associated with
this function.
To use the special zero:
1. Set your system to base pressure.
2. Send the command:
Z 2 value
where
value
is expressed as a percentage of full scale pressure (% FS pressure):
value:
known base pressure reading transducer’s full scale
To remove the special zero correction, refer to
Removing the Sensor and Special Zeros
, page 40.
Removing the Sensor and Special Zeros
The [
Z 3
] command removes the sensor zero [
Z 1
] and the special zero [
Z2 value
] correction factors stored in
memory, and is used to determine the uncorrected signal from the pressure transducer. Each time a sensor is
zeroed, the offset changes and the pressure value is updated. In some applications it may be important to keep
the zero offset within a specific range. There is no request associated with this function.
To remove the zero corrections, send the command:
Z 3
