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Teledyne API Model 480L O
3
Monitor User Manual
09419A DCN8342
The intensity of light is converted into a voltage by a high resolution A/D (analog-
to-digital) converter. The digitized signal and other variables are used by the CPU to
compute the concentration using the above formula.
About every 2.5 seconds the monitor completes a measurement cycle consisting of a
1 second wait period for the sample tube to flush, followed by a 150 ms
measurement of the UV light intensity to obtain I. The sample valve is switched to
admit scrubbed sample gas for 1 second, followed by a 150 ms measurement of the
UV light intensity to obtain Io. Measurement of the Io every 2.5 seconds eliminates
instrument drift due to changing intensity of the LED caused by aging and dirt.
The electronic platform is based on a Controller Area Network (CAN) bus modular
system. CAN is the central networking system that enables communication among
all the parts and facilitates centralized diagnoses of errors, as well as configuration
of all the parts. CAN bus technology allows for a uniform cable architecture with
interchangeable 6-pin connectors configured for power (5 V and 24 V) and
communications (CAN high and CAN low serial lines).
The Mainboard is the main hub, which not only contains the Central Processing
Unit (CPU) that communicates with other modules, but also directs power and
communication distribution.
The ozone sensor module consists of its own board controlled by a microprocessor
that receives messages from and sends information to the Mainboard on the CAN
network. It acts on the messages from the Mainboard, and it conducts local
operations, such as activating valves or controlling manifold temperature.
Summary of Contents for 480L
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