Teledyne HASTINGS 2002, Инструкция по эксплуатации, Страница: 14 / 49

page 14
3.6 UNITS Mode
The Model 2002 can display the measured pressure in different pressure units, Torr, mbar or Pascal
(optional) . To switch between the units follow these instructions:
Press the MODE button until the UNITS field is lit. Press the blue circular down arrow or up
arrow simultaneously. The UNITS light will now flash. Use the up and down arrows individually to
select the desired unit.
Another commonly used unit is mTorr which is also known as the micron (short for micron of Hg).
One Torr is equal to 1000 mTorr. The table below illustrates how to interpret the display in
mTorr.
mTorr Conversions
1 mTorr = 1.00 x 10
-3
Torr
10 mTorr = 1.00 x 10
-2
Torr
100 mTorr = 1.00 x 10
-1
Torr
Default Calibration Restoration
The UNITS mode is also used to load default calibration data in rare cases where the transducer
EEPROM has become corrupted. The default calibration data should be considered an approxi-
mate calibration because the values entered in the controller’s software are based on averaged data
collected over a large number of transducers. While this type of calibration download is not a true
calibration, it does allow the user to return the unit to a reasonable status from which a full calibra-
tion can be easily performed.
With the transducer at atmosphere place the 2002 in the UNITS mode. Press the up and down
arrows simultaneously (UNITS light will flash). Simultaneously press the “ZERO” button, up and
down arrows. The 2002 will now read 760 Torr (±200 Torr). A full calibration should now be
performed (see section 3.4).
TABLE 2
Torr atm mbar Pa psi
Torr (mm Hg) 1 1.32x10
-3
1.3332 133.32 1.934x10
-2
mTorr (micron Hg) 10
-3
1.32x10
-6
0.00133 .13332 1.934x10
-5
atm (atmosphere) 760 1 1013.23 1.013x10-5 14.7
mbar (millibar) 0.75 9.869x10
-4
1 100 1.45x10
-2
Pa 7.5x10
-3
9.869x10
-6
0.01 1 1.45x10
-4
psi (lb/in
2
) 51.72 6.805x10
-2
68.953 6895.3 1
A schematic of the rear panel of the Model 2002 control unit is shown in Figure 4.1 ( Rear Panel
Figure). The transducer is connected to the control unit via an 8-pin DIN connector on the rear
panel. An I/O cable can be connected via a 7-pin DIN connector on the rear panel. The I/O cable
provides an analog output signal, a remote zero input capability, high and low alarm TTL Out-
puts, and a + 5 VDC TTL signal. The I/O cable also provides an analog ground and a digital
common.