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Infrared Gas Analyzer Start-up and Operation
3-7
Teledyne Analytical Instruments
The CPU also provides appropriate control signals to the Displays,
Alarms, and External Valve Controls, and accepts digital inputs for external
Remote Zero and Remote Span commands. It monitors the power supply
through an analog to digital converter as part of the data for the system
failure alarm it performs timing and linearizing tasks too.
The RS-232 port provides two-way serial digital communications to
and from the CPU. These, and all of the above electrical interface signals are
described in detail in chapter 3 Installation.
3.6 Linearizer
The output of the NDIR analyzer bench is non-linear (this is due to the effect
known as “Beers Law”). Figure I shows this non-linear response.
In order to produce a linear signal response, a compensation curve is
required (see Figure II). Therefore, a linearizer software routine is included
to create a linear response. Refer to section 4.3.7 and 4.8.2 to see how
NDIR Bench Output
Figure I
Gas Concentration
linearizer is programmed.