Requirements to the Glue Logic
Characteristics of work-cell control software
From the observation of the current manufacturing work-cell control
software systems, the manufacturing control software should have
following characteristics:
- Manufacturing control softwares should have sense of time;
- As many processes runs concurrently in a work-cell control system,
abilities to control other process, such as starting, terminating,
synchronizing, and waiting for other processes are required. For
the maintenance, those operation should be denoted concisely;
- Exception handling and the control of the exception handlers are
very important for the application;
- Abilities to exchange information among multiple processes running
on multiple work-cell control system are vital for the software;
- Abilities of information sharing and keeping consistency are
required;
- Program modules are frequently added, deleted and altered, even in
the manufacturing line is under operation.
Proposing programing paradigms
In order to ease application programming, the following programming
paradigms are strongly recommended:
- Build manufacturing control program system as the collection of
modules;
- To bind modules, an infrastructural system should be introduced.
All modules should be designed to be the infrastructural system
compliant;
- In order to virtualize devices and work-piece in a work-cell, the
cell model can be build in the shared data space;
- In order to virtualize manufacturing control processes, the
inter-process communication should be done in the form of the
message passing.
The Glue Logic is designed under the paradigm shown above.
Requirements for the Glue Logic
The Glue Logic is the minimum system to bind program modules flexibly,
and should fulfill following requirements:
- Data sharing among independent modules should be realized;
- Each modules can be sepalately developed and compiled;
- Modules are bound at run-time and are easy to add, delete and substitute;
- Data and modules can be accessed in fully abstracted ways;
- Keeping shared data consistent and implementing mutual execution;
- Models all objects in the work-cell within shared data space;
- Models all event occurrence by message sending;