TELEPHONE:
650-969-8811
TOLL-FREE (US/Canada):
800-446-8811
FAX:
650-965-0764
EMAIL:
WEB:
18
of
30
Examples
CDG pressure: 2.340 Torr
p
275 / CEP pressure:
HI
Output:
2.340e+0, HI
CDG pressure:
OFF
p
275 / CEP pressure:
OFF
Output:
OFF, HI
SET POINT 1 is assigned to 275 / CEP (Relay ON)
SET POINT 1 HI pressure:
60 mTorr
1
SET POINT 1 LO pressure:
57 mTorr
Output: 60.0e-3, 57.0e-3, 1, PIR
SET POINT 2 is assigned to CDG (Relay OFF)
SET POINT 2 HI pressure:
OFF
2
SET POINT 2 LO pressure:
OFF
Output:
0.00, 0.00, 0, CDG
Control unit will output LO for either pressure gauge if display reads LO.
Analog Output
The Terranova® 907 has a calibrated, 12-bit resolution, logarithmic analog output available for
use as a secondary method to read measured pressure values. Analog output voltage can be
accessed through the INPUT / OUPUT 15-pin D-sub connector port. The unit outputs 0.50 V per
pressure decade (or order of magnitude). LO pressure value corresponds to 0.00 V; HI / OFF
pressure value corresponds to approximately 4.52 V. Analog output is valid only for the
selected gauge on the control unit. See
Table 1
for pin configuration.
The analog output voltage can be approximated using the displayed pressure measurement by
V
= 0.50 * log
10
(100 *
P
)
where
P
is the pressure reading in mTorr and
V
is the analog output in volts. For example, if
P
is
equal to 10 mTorr,
V
(rounded to the nearest hundredth) is equal to 1.50 V.
Table 3
lists sample
analog output and corresponding pressure values. For example, if analog output is 3.00 V, the
corresponding pressure reading is 10.0 Torr.
