Brooks Instrument XacTorr CMX160 - Manual (Page 33)

p.27
The temperature indicator status can also be monitored remotely through pin 1
of the DB15 connector, or through pin 3 of the DB9 connector. This pin is
normally driven high to 3.3 volts when the temperature LED is Green.
4.6 ZEROING THE CMX
When the gauge is placed into operation for the first time or after a shut down of
the system, ZERO should be set using the following steps.
• Adjust ZERO at the ambient temperature at which the gauge is normally
operated.
• The CMX cannot be zeroed if the pressure is too high or if the gauge has not
reached a stabilized operating temperature (Green LED).
1. Pump the system down to a pressure that is at least 5 decades below the full
scale range of the device. See the ZERO Pressure Chart below. (For 100mT
device, check that the installation orientation is the same as the calibration
orientation):
Table 9: ZERO Pressure Chart
2. Allow the device to warm-up and settle (see “Recommended Ready To Use
Times” on page 26).
3. Press the ZERO pushbutton or momentarily connect the remote zero trigger
signal in the D-Sub connector to signal ground.
The CMX will attempt to correct the ZERO adjustment in a series of steps over
a period of a few seconds. While ZERO adjustment is being performed
automatically, the STATUS LED will blink GREEN; repeating until ZERO
adjustment is completed or aborted.
If ZEROING is completed successfully, the STATUS LED returns to its normal
color (GREEN), and the output signal should be 0 volts (±2 mV).
If ZERO adjustment is aborted, the STATUS LED will blink RED three times
and return to its normal color (GREEN). The ZERO adjustment will be returned
to the value it had before the ZERO Set push button was depressed.
Full Scale
Range
Highest Pressure for Proper Zero
Adjustment
0.1 Torr 1 X 10 -6 Torr
1 Torr 1 X 10 -5 Torr
2 Torr 2 X 10 -5 Torr
5 Torr 5 X 10 -5 Torr
10 Torr 1 X 10 -4 Torr
20 Torr 2 X 10 -4 Torr
100 Torr 1 X 10 -3 Torr
1000 Torr 1 X 10 -2 Torr
4.0
_OPERATION