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HVG-2020B Instruction Manual
2.3.3. Analog Output
The analog signal output is configurable via digital communications. See the instrument label to determine how
the instrument was configured at the factory. In Hastings power supplies, the analog output is routed to the
display and is also available at terminals on the rear panel. If a Hastings supply is not used, the output is
available on pin 5 of the "D" connector.
The analog output is user selectable to be non-linear, linear, logarithmic or dual slope. Multiple voltage or
current ranges are available: 0-1 VDC, 0-5 VDC, 0-10 VDC (short-circuit protected, 1 kΩ min load), 0-20 mA, 4-
20 mA (short-circuit protected, 1.2 kΩ max load).
The standard output of the pressure meter is a 1 to 9 VDC signal logarithmically related to the pressure (9 VDC
= 1000 Torr, 1 VDC/decade). Other full scale and slope values are selectable/settable via the display or serial
communications. Predetermined linear and logarithmic selections are:
Options 1 to 11: Linear and Logarithmic Analog Outputs
Option
01: 0-1 V Linear
0.001 V/Torr
02: 0-5 V Linear
0.005 V/Torr
03: 0-10 V Linear
0.010 V/Torr
04: 4-20mA Linear
0.016 mA/Torr
05: 0-20mA Linear
0.020 mA/Torr
06: 0-10V Log
1.00 V/dec
07: 0-10V Log
1.00 V/dec
08: 0-10V Log
1.00 V/dec
09: 0-10V Log
1.286 V/dec
10: 4-20mA Log
2.00 mA/dec
11: 0-20mA Log
2.50 mA/dec
12: Non-linear
n/a
13: Dual Slope
n/a
There is also a custom defined logarithmic output. All the user needs to do is input the desired volts per
decade into S33 and the expected voltage at 1000 Torr into S32 (See Section 5.2.8). However, the analog
output must be put into the custom mode (S31 = 0x06) before it will accept the inputs from the user.
NOTICE: Predetermined logarithmic voltage selections should be used in the 0–10 VDC mode, otherwise
the output will be forced to fit that range; the slope and/or full-scale values will not be as listed. In 4-
20 mA mode, the output current will not go below 3.7 mA.
EAR99 Technology Subject to Restrictions Contained on the Cover Page
@ .0001
Slope
Torr
0.0000 V
0.0000 V
0.0000 V
4.000 mA
0.000 mA
1.0000 V
1.6249 V
2.0000 V
1.1600 V
6.000 mA
2.500 mA
0.3750 V
0.0005 V
P(Torr) from
@ 1000
V(volts) or I(mA)
Torr
�� = 1000 ∗ ��
1.0000 V
�� = 200 ∗ ��
5.0000 V
�� = 100 ∗ ��
10.0000 V
�� = 62.5 ∗ �� − 250
20.000 mA
�� = 50 ∗ ��
20.000 mA
�� = 10
8.0000 V
(
�� = 10
8.6249 V
�� = 10
9.0000 V
.
�� = 10
10.1620 V
�� = 10
20.000 mA
�� = 10
20.000 mA
See Option 12 below
5.6590 V
See Option 13 below
10.0000 V
V(volts) or I(mA)
from P (Torr)
�� = 0.001 ∗ ��
�� = 0.005 ∗ ��
�� = 0.01 ∗ ��
�� = ( �� + 250 ) 62.5
�� = 0.02 ∗ ��
(
)
�� = log
)
.
�� = log
(
)
�� = log
(
)
.
�� = 1.286 log
. (
)
�� = 2 log
. (
. )
�� = 2.5 log
⁄
�� + 5
�� + 5.6249
�� + 6
�� + 6.304
�� + 14
�� + 12.5
Page 11 of 40
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