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MX4428 MXP Engineering / Technical Manual Document: LT0273
MXP Loop Filter Board
Page 9-8 24 March 2006 Issue 1.5
9.5 CO PROCESSING
9.5.1 CALIBRATION AND TEMPERATURE COMPENSATION
The CO reading of the detector is returned as input AI0 of the device ASIC. The CO
readings are adjusted depending on a calibration factor set at the factory and stored in
EEPROM.
9.5.2 “ENHANCEMENT”
Figure 9.3 shows the amount by which CO readings are increased depending on the
temperature rate of rise. (This is the same for the CO detector as the Photo detector.)
The default enhancement multiplier parameter is 12. The graph (
Figure 9.3) shows the effect
of this factor and also the effect of an alternative parameter of 6.
If enhancement is disabled, (or less efficiently if the enhancement multiplier parameter is set
to 0) the multiplier is exactly 1.
9.5.3 CO PROCESSING
Subtractor
+
-
Calibration
Adder
Exponential
Filter
Subtractor
Enhancement Factor
derived from Heat RORCV
(1 if no enhancement)
Adder
Multiplier
Slope
Limiter
TV = Tracked Value = Zero CO Value
Raw
Value
-
+
+
++
+
-
--
-
Al
a
rm Thr
es
h
o
l
d
Alarm
Subtractor
S
ubtractor
Comparator
C
omparator
PreAlarm Threshold
PreAlarm
CVEnh
(CV to FIP)
SLV
Constant stored
in detector eeprom
CO Filter
Divisor
CO Step Limit
Figure 9.5 CO Processing Diagram