| Data Solutions always write software which is intended
to be as portable as possible. The following rules are used
:-
1. Use of loops eliminate typing errors and make configuration
easier.
2. The software follows the classical function structure where
possible.
3. The software is object orientated.
4. The software is a classic three level system where the
levels are as follows:
Level 1 – Hardware
Level 2 – Software Driver Routines
Level 3 – Software Core Application
Levels 2 and 3 can be thought of as a planet representing
the core software and satellites representing the driver routines.
Classical Function Structure
There are two classical rules for function design :-
(1) Functions should only ever have one entry point and
one exit point
The software adopts this rule where practicable, however,
for the reasons of saving time, if a function contains various
tests then it is imperative that the function exits as soon
as that test is satisfied.
(2) Test the most likely outcome first.
Data Solutions software always adopts this rule.
Object Orientated Approach
When designing the software to control a system, we divide
the system into individual objects placed into one of several
groups. Each item within the same group is treated exactly
the same from a controls perspective and therefore we can
rely upon standard controls modules for each group type.
Standard groups might be a conveyor, a pump or a manual control
panel.
The main part of the software need only concern itself with
alarms and status bits reported by each of the groups, thus
keeping on-site commissioning to a minimum and ensuring that
software modules are as portable as possible.
|