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MAN0530 Issue 15 - 07/17
Searchline Excel
2104M0506
2. OVERVIEW
417mm (SR)
160mm
The solid state, photovoltaic detectors used in Searchline Excel provide an exceptional dynamic
range and superb temperature and long term stability. These features contribute strongly to the
solar immunity and stability of Searchline Excel.
The Receiver contains all of the electronics necessary to amplify, condition and process the
signals received by the infrared detectors. The advanced signal processing of Searchline Excel
employs two microprocessors.
One microprocessor, the Digital Signal Processor (DSP), is used to perform the necessary
intensive signal processing calculations.
The other microprocessor, the microcontroller, controls the overall function of the unit and
performs the final calculations to determine the correct gas reading and output state.
The primary output of the Receiver is a signal in the range 4 - 20mA and is available as either
source or sink options. For most applications, the output is calibrated for a range of 0 to 5 LEL.
m. (See Appendix B for the explanation of LEL.m and other terms)
The Receiver also features an RS485 output which is used to communicate with the associated
SHC1 Handheld Interrogator. The SHC1 is used to perform final alignment, commissioning,
functional testing and diagnostic procedures.
The Receiver window is heated to minimise condensation, frosting and the buildup of snow.
The level of heating applied is controlled by the microcontroller and is adjusted from zero to
maximum depending on the window temperature.
Electrical connections to the Receiver are made via wires which run through the protective
flexible conduit. There are six Receiver wires, red (+24V), black (0V), white (4 - 20mA), orange
(RS485 A), blue (RS485 B) and green / yellow (GND).
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