2 SOFWARE DESIGN OVERVIEW
The device software can be conceptually categorized into several elements as follows:
● The system level software
● The platform software
● The protection and control software
These elements are not distinguishable to the user, and the distinction is made purely for the purposes of
explanation. The following figure shows the software architecture.
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Protection and Control Software Layer
Fault locator
task
Disturbance
recorder task
Sampling function
Control of output contacts
and programmable LEDs
Sample data + digital
logic inputs
System Level Software Layer
System services (e.g. device drivers) / Real time operating system / Self-diagnostic software
Control of interfaces to keypad , LCD, LEDs,
front & rear ports.
Self-checking maintenance records
Hardware Device Layer
LEDs / LCD / Keypad / Memory / FPGA
Protection Task
Programmable & fixed
scheme logic
Signal processing
Coprocessor protection
algorithms
Supervisor task
Platform Software Layer
Event, fault,
disturbance,
maintenance record
logging
Remote
communications
interfaces
Front panel
interface
(LCD + Keypad)
Local
communications
interfaces
Settings database
Protection algorithms
Figure 25: Software Architecture
The software, which executes on the main processor, can be divided into a number of functions as illustrated
above. Each function is further broken down into a number of separate tasks. These tasks are then run according
to a scheduler. They are run at either a fixed rate or they are event driven. The tasks communicate with each other
as and when required.
Chapter 4 - Software Design P446SV
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