Control Programs Interpreter

This program is the main tool in running the designed control programs. It implements the following functions.

Implementation of the SFM library - a set of function modules used in the control programs. One of the significant advantages of the usage of this library is that the timing characteristics of each module are documented and can easily be rechecked when the target platform is chosen, with this information the calculation of the time it takes to execute one Signal Flow Graph or the whole system can easily be calculated, further plan for development of this system is the addition of this calculation capability through extensions to the Interpreter and the Program Generator.
Handling of network communication - used for connection to other Interpreter programs or to the visualization/user input component.
Hardware drivers - required so that the control programs can interact with hardware devices.

The Interpreter program has been mainly used under desktop Windows operating systems. Further development is planed to include porting the Interpreter to Windows CE.NET & RT Linux operating systems.

Messaging protocol

The messaging protocol used for communication between multiple running instances of the Interpreter & Visualizator program is designed as a content oriented addressing protocol, which allows the protocol to be easily ported to Control networks such as CAN or Profibus. Currently the preferred medium used is Ethernet communication, no special requirements are set on the Ethernet communication. Over ethernet the protocol uses point to point communication, some Interpreter programs are marked as Message Concentrator nodes, which allows other Interpreters/Visualizators to connect to such Message Concentrators and request reception of messages of interest. With this framework multiple Visualizator programs can be running on different computers thorugh out the control network and monitor any set of variables. Visualizators can also connect through the Internet and monitor system parameters (if Internet connection to the control system is available and firewalls have been configured to allow connections to a specific TCP port). In case hard-real time requirements are required for deploying a distributed control system, which needs to use Ethernet medium, we have developed custom communication protocol which provides contention free communication over the shared Ethernet medium. With this protocol the timing characteristics of the data transfer over the network are fixed and well-known (after initial timing measurements). Together with the ability to analyze the created control programs for their execution time characteristics, the system designer is able to evaluate if the designed system will meet the timing requirements. Further information about the development of this hard real-time protocol can be found here

3 Dec 2006