Kendro HERAcell 150, Operating Instructions Manual

Page: 110 / 251

Name/Name Datum/Date Benennung/Designation
Erstellt/Prepared
D.Dornseiff 01/15/98
Index Änderung Name/Name Datum/Date
Service Handbuch HERAcell 150
Service Manual HERAcell 150
C 202613 D.Dornseiff 06/26/03
Dokumentnr./Document No. Seite/Page
Datei/File
50051109_04_EN_C.doc 50051109 / C 4/ 9
Weitergabe sowie Vervielfältigung dieser Unterlage, Verwertung oder Mitteilung ihres Inhalts nicht gestattet, soweit nicht ausdrücklich zugestanden. Zuwiderhandlungen ver-
pflichten zu Schadensersatz. Alle Rechte für den Fall der Patenterteilung oder Gebrauchsmustereintragung vorbehalten. © Kendro Laboratory Products GmbH, Germany
4.2 DESCRIPTION OF ELECTRONIC CONCEPT
The system in question is a PC-bus-driven measurement and control system, oper-
ating in the "single master" mode.
In other words, the total system is made up of a number of components with separate

P

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

P controls the display on the unit door, while another one, on the sen-
sor board, controls the fan and generates measured values for temperature and
CO
2
(only if the thermal conductivity detector is installed).
Ann additional

P in the O
2
sensor’s separate electronics performs the calculation of
the O
2
value and switches the O
2
valve based on the specifications of the processor
on the main board. Both the O
2
sensor’s electronics as well as the electronics board of
the flask rotation equipment on which the power drivers for the DC motors are
mounted, have a separate mains power supply.
If the unit is equipped with an infrared metering cell, this cell also has its own slave

P.
There are also other bus subscribers aside from the "slaves", e.g., the digital tem-
perature 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 (e.g., when
switching from a CO
2
thermal conductivity detector to an infrared detector), 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.