Teledyne 6200T - Sulfides Analyzer - Manual (Page 304)

Principles of Operation Model 6200T Total Sulfur Analyzer
304 Teledyne Analytical Instruments
The motherboard is directly mounted to the rear panel and collects data, performs signal
conditioning duties and routes incoming and outgoing signals between the CPU and the
analyzer’s other major components.
Concentration data of the 6200T are generated by the Photo Multiplier Tube (PMT),
which produces an analog current signal corresponding to the brightness of the
fluorescence reaction in the sample chamber. This current signal is amplified to a DC
voltage signal (front panel test parameter PMT) by a PMT preamplifier printed circuit
assembly (located on top of the sensor housing). PMT is converted to digital data by a
bi-polar, analog-to-digital converter, located on the motherboard.
In addition to the PMT signal, a variety of sensors report the physical and operational
status of the analyzer’s major components, again through the signal processing
capabilities of the motherboard. These status reports are used as data for the SO
2
concentration calculation (e.g. pressure and temperature reading used by the
temperature/pressure compensation feature) and as trigger events for certain warning
messages and control commands issued by the CPU. They are stored in the CPU’s
memory and, in most cases, can be viewed through the front panel display.
The CPU communicates with the user and the outside world in a variety of ways:
 Through the analyzer’s front panel LCD touch-screen interface
 RS-232 and RS-485 serial I/O channels
 Various analog voltage and current outputs
 Several digital I/O channels
 Ethernet
Finally, the CPU issues commands (also over the I 2 C bus) to a series of relays and
switches located on a separate printed circuit assembly, the relay board (located in the
rear of the chassis on its own mounting bracket) to control the function of key
electromechanical devices such as valves and heaters.