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6.9
Test points
The backplane has a set of test points that allow you to measure the voltage output of the
base input/output (I/O) card.
Figure 6-1: Lower enclosure showing test points on the backplane
Each test point is labeled with a voltage value that, when measured with a voltmeter,
should give a measurement equal to what is displayed on the label. A reading that does
not match this label may indicate a faulty base I/O card. Try swapping out the suspect card
with a different one, and take another measurement. To get a measurement for a test
point, touch the voltmeter’s negative probe to the
DGND
test point and touch the
voltmeter’s positive probe to the desired test point.
The test points are associated with the following gas chromatograph (GC) components:
Table 6-1: Backplane test points and associated GC components
Test point
GC component
Tolerances for
DC voltages
VIN
Voltage in
N/A
I RTN
Isolated return
N/A
I 24V (regulated)
Isolated voltage (loop power)
24 V (±2.4 V)
24V (regulated)
GC power
24 V (±2.4 V)
17V5
Preamplifier (input for the bridge circuit)
17.5 V ±0.5 V
12V
Optional I/O cards
12 V ±0.6 V
5V1
System chips
5.1 V ±0.25 V
3V4
System chips
3.4 V ±0.15 V
FVIN
Field voltage input
24 V ± 1.5 V
FVGND
Field voltage ground
0 V ± 3 V
The input voltage range for a DC power supply is between 23.5 and 24.5 volts.
Troubleshooting
Reference Manual
June 2022
2-3-9000-744
194
Emerson.com/Rosemount
Summary of Contents for Rosemount 700XA
Page 1: ...Reference Manual 2 3 9000 744 Rev L June 2022 Rosemount 700XA Gas Chromatograph ...
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Page 30: ...Overview Reference Manual June 2022 2 3 9000 744 30 Emerson com Rosemount ...
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