User guide

GC Output Signals 14
Advanced User Guide 369
Signal Types
When assigning detector signals, use the [Mode/Type] key and
choose from the Signal Type parameter list, or press a key or
combination of keys.
[Front], [Back], [–], and [Column Comp] will work, alone or in
combination. For example, press [Back] for back detector or
[Back][–][Front] for back detector minus front detector. The
menu choices for signal subtraction (Front - Back and Back -
Front) only appear if the front and back detectors are of the
same type.
The nondetector signals are test plot, thermal, pneumatic, and
diagnostic. Access them by pressing [Mode/Type]. Diagnostic
signals are for use by your service representative and are not
described in detail here.
Signal type can be programmed as a run time event.
Value
Value on the signal parameter list is the same as Output on the
detector parameter list if your signal type is Front or Back. If you
are subtracting one signal from another (as in Front – Back), the
signal Value will be the difference. You cannot enter a setpoint
for Value.
A conversion factor may be involved when interpreting
Value—for example, one FID unit is one picoamp; one uECD unit
is 1 Hz. The units for detector and other signals are listed below.
Table 84 Signal conversions
Signal type 1 display unit is equivalent to:
Detector:
FID, NPD 1.0 pA (1.0 × 10
-12
A)
FPD 150 pA (150 ×10
-12
A)
TCD 25 mV (2.5 × 10
-5
V)
µECD 1 Hz
Analog input board (use to connect the
GC to non-Agilent detector)
15 µV
Nondetector:
Thermal 1 °C