4.2 Description Of Electronic Concept - Thermo Scientific BB 150 User Manual

4.2 DESCRIPTION OF ELECTRONIC CONCEPT

The system in question is a PC-bus-driven measurement and control system,
operating in the "single master" mode.
In other words, the total system is made up of a number of components with separate
μP's, with one of these (the master on the main board) assuming management and
control of the entire PC bus system, as well as performing the actual evaluation of the
signals and regulatory functions.
The so-called "slaves" perform the input/output and measurement tasks "on site".
Thus, one μP controls the display on the unit door, while another one, on the
sensor board, controls the fan and generates measured values for temperature
and CO (only if the thermal conductivity detector is installed).
2
There are also other bus subscribers aside from the "slaves", e.g., the digital
temperature sensor, LM 75, and the NVRAM`s (memory building blocks) on the
sensor and main boards, all of which send their values directly to the master via the
bus system, and receive instructions from it.
This system offers the advantage of having a self-configurable design, and that it is
"open" for the addition of optional equipment in the future.
Power to the electronic boards is provided by a combinational circuit component.
Name
Prepared
Index Name
50078923_04_CN
File
Date
JF 05.07.13
Date
Designation
Service Manual BB 150
Document No.
50 079 823
Page
3/ 3