Teledyne 9110T instruction manual Teledyne Analytical Instruments 339

Model 9110T NOx Analyzer Principles of Operation

The core of the analyzer is a microcomputer/central processing unit (CPU) that controls various internal processes, interprets data, makes calculations, and reports results using specialized firmware developed by Teledyne. It communicates with the user as well as receives data from and issues commands to a variety of peripheral devices via a separate printed circuit assembly onto which the CPU is mounted: the motherboard.

The motherboard is directly mounted to the inside 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.

Data are generated by the sensor module which outputs an analog signal corresponding to the amount of chemiluminescence present in the reaction cell. This signal is converted into digital data by a unipolar, analog-to-digital converter, located on the motherboard.

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 various concentration calculations and as trigger events for certain warning messages and control commands issued by the CPU. This information is stored in memory by the CPU and in most cases can be viewed by the user via the front panel display.

The CPU issues commands via a series of relays and switches (also over the I2C bus) located on a separate printed circuit assembly, called the relay PCA, to control the function of key electromechanical devices such as heaters and valves. It also issues some commands directly to the Sensor module (e.g. initiate Electric Test or Optical Test).

By controlling the state of various valves the CPU directs the flow of sample gas through the various gas paths of the analyzer (NO measurement path; NOx measurement path; Auto Zero Path). Based on which path is active, the CPU interprets the sensor output to derive raw data representing concentrations for NOx, NO and zero (dark condition), accesses the operational data stored in memory then calculates final concentrations for NOx, NO and NO2.

The CPU communicates with the user and the outside world in several ways:

∙Through the analyzer’s front panel LCD touch-screen interface

∙Through the serial I/O channels

∙Various analog voltage and current outputs

∙Several sets of Digital I/O channels

∙Ethernet

13.3.2. CPU

The unit’s CPU card, installed on the motherboard located inside the rear panel, is a low power (5 VDC, 720mA max), high performance, Vortex86SX-based microcomputer running Windows CE. Its operation and assembly conform to the PC 104 specification.

Teledyne Analytical Instruments 339