GE Datex-Ohmeda S/5 - 2 System Description; Introduction; Bus Structure; Figure 2 General Bus Structure of S;5 System

System description
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Document no. M1137263-04
2 System description
2.1 Introduction
Datex-Ohmeda monitors build up a freely configurable modular system. The architecture is
designed to enable different module combinations so that the user is able to get the desirable
parameter and feature set. This modular approach makes it possible to add new features
when they are needed.
2.2 Bus structure
The operation of Datex-Ohmeda monitors is based on two communication channels, the CPU
bus and module bus.
In the 5-Module Central Unit, PC boards receive power from the F-CPU power supply and the
parameter modules receive power from a separate power supply in the 5-Module Frame unit.
These power supplies are both fed by the N-AC Power Unit. In the 8-Module Central Unit, F-CU8,
all PC boards connected to the CPU bus, as well as the parameter modules attached to the
module bus receive power from the same power supply, which is an integral part of the Central
Unit, F-CU8.
Figure 2 General bus structure of S/5 system
The CPU bus is a communication channel used only for internal data transfer. It is based on the
ISA bus used in IBM PC computers. Data is transferred on this 16 bit wide bus using the CPU
clock frequency.
The module bus is used to connect the parameter modules to the Central Unit. The bus is based
on the industry standard RS-485, which uses a differential serial method to transfer data. This
type of bus is robust and it allows parameter modules to be inserted or removed while the
power is on. The module bus uses a 500 kbps data transfer rate and can be used for longer
distances than the CPU bus, e.g. for external frame connections.
The RS-485 type of serial communication supports so-called multidrop or party line
connections. This means that all parameter modules connected to the module bus use exactly
the same lines for communication. The advantage of this is that all bus connectors are
identical and the modules can be connected in any order and position.
UPI CPU
Power
Supply
Unit
Module Bus
Display
Controller
CPU Bus
Parameter
Module
Parameter
Module
Parameter
Module