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Analog Output
The Terranova® 752A has analog output available for use as a secondary method to read the
high voltage and current values shown on the HIGH VOLTAGE and CURRENT display,
respectively, of each channel. The unit outputs a 0 V to 10 V signal for each type of analog
output. Analog output may be accessed through both the MISCELLANEOUS I/O or AUXILIARY
I/O ports for CHANNEL 1 and AUXILIARY I/O port for CHANNEL 2. See
Table 5
and
Table 6
for
pin configuration.
High Voltage Output
The high voltage analog output is based on the value shown in the HIGH VOLTAGE display for
each respective channel. The analog output function provides a normalized value (i.e. divided
by 1000) of 1 V per 1 kV for the high voltage output. For example, an output of 7.5 V
corresponds to 7.5 kV. The high voltage analog output may be accessed through PIN 14 of the
MISCELLANEOUS I/O port or PIN 24 of the AUXILIARY I/O port for CHANNEL 1 and PIN 9 of the
AUXILIARY I/O port for CHANNEL 2.
Current Output
Three different user-selectable voltage ranges
–
two linear, one logarithmic
–
are available to
output the current value shown on the CURRENT display of each channel. Linear output is
available in the following two scales: 200 µA per 1 V up to 2000 µA or 2 mA per 1 V up to
20 mA. The lowest recommended value for accurate readings when linear output is selected is
1% of full scale. The default current analog output scale is 2 mA per 1 V.
The logarithmic analog output scale requires the user to convert the voltage output into a
current measurement. Current,
I
, as a function of the analog output,
V
, can be approximated by
I
= 10
(
V
-8)
where
V
is in volts and
I
is in amperes. For example, if
V
is equal to 4.903 V,
I
(rounded to the
nearest one) is approximately 8.0 x 10
-4
A or 800 µA.
Table 7
lists sample analog output and
corresponding current values.
Analog Voltage [V]
Current
1.0
0.1 µA
2.0
1 µA
3.0
10 µA
4.0
100 µA
5.0
1 mA
6.0
10 mA
7.0
100 mA
8.0
1 A
Table 7
. Analog output and calculated current values
