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Operating Instructions Model GFC7000TA Carbon Dioxide Analyzer
Teledyne Analytical Instruments 145
6.15.1.2. Control Inputs
These inputs allow the user to remotely initiate Zero and Span calibrations. Two methods for energizing
the inputs is provided below; the first using the internal +5V available on the CONTROL IN connector and
the second, if an external, isolated supply is employed.
Table 6-25: Control Input Pin Assignments
INPUT STATUS CONDITION WHEN ENABLED
A
EXTERNAL ZERO
CAL
Zero calibration mode is activated. The mode field of the display will
read ZERO CAL R.
B
EXTERNAL SPAN
CAL
Span calibration mode is activated. The mode field of the display will
read SPAN CAL R.
C
Unused
D
Unused
E
Unused
F
Unused
DIGITAL GROUND Provided to ground an external device (e.g., recorder).
U
DC power for Input
pull ups
Input for +5 VDC required to activate inputs A - F. This voltage can be
taken from an external source or from the “+” pin.
+ Internal +5V Supply
Internal source of +5V which can be used to activate inputs when
connected to pin U.
There are two methods to activate control inputs. The internal +5V available from the “+” pin is the most
convenient method (Figure 6-18). However, to ensure that these inputs are truly isolated, a separate,
external 5 VDC power supply should be used.
CONTROL IN
A B C D E F U +
S
P
A
N
Z
E
R
O
CONTROL IN
A B C D E F U +
-
+
5 VDC Power
Supply
S
P
A
N
Z
E
R
O
Local Power Connections
External Power Connections
Figure 6-14: Control Inputs