Glossary

core

The central part of the MatPLC; virtual backplane. Each module plugs into this core.

custom-made module

A module written in the C language because none of the generic or specific modules provided by the MatPLC were suitable.

functional specification

A written statement detailing what a system will do.

generic module

A module that comes with the MatPLC and is used without modification.

HMI module (or MMI module)

A module that interacts with the operator.

I/O module

A module that connects to the "real world", or sometimes to a slave PLC over a bus or other connection.

Linux

The operating system for which the MatPLC is designed.

matplc.conf

The traditional name for the main configuration file of the MatPLC.

logic engine

A module that does the actual logic, decision making and calculation.

modularity

A quality of a system where it consists of various parts which separate cleanly and fit together well. High modularity costs some design time but pays back well through clarity, elegance, maintainability and flexibility.

module

A component of the MatPLC architecture. Several modules running together make a useful MatPLC. Note that other parts of an installation may also have modules - the machine itself, I/O hardware, the software you write for the MatPLC, the Linux kernel, etc.

point

The basic unit of storage and communication within the MatPLC. Points may be 1-bit, corresponding to discrete inputs, outputs, internal/memory coils, flags &c, or multi-bit (up to 32-bit), corresponding to analog inputs, outputs, integer or floating point registers &c. Each point has a name by which it is known throughout the MatPLC.

scan

Many modules, especially logic engines, work in a cycle. One repeat is called a scan. It begins by obtaining a copy of all the points from the MatPLC core. It then evaluates all the logic or does all the calculations (depending on the module). Finally, all changed points are written back to the MatPLC core - this only happens at the end of the scan, so if the logic wrote a point several times with different values, only the last value is ever seen by any other module.

specific module

A module that is created for a particular project using the tools provided by the MatPLC. Unlike a generic module, it does not directly come with the MatPLC.

$Date: 2004/12/28 05:32:09 $