SEFO: an integrated approach for automation and supervision

This project is one of the first using this coupling, and here is a report on the operation, shaped with Laurent PONCELET, in charge of the project within SEFO.

A complete supervision system

The system comprises:

• a Premium controller for the treatment plant
• three Twido controllers associated with each of the water wells
• an optic fibre Ethernet network connecting the controllers and the SCADA software, under Modbus IP protocol
• an OPC server, the OFS server by Schneider Electric
• a Topkapi server station with Text To Speech Remote Alarm Notification and Summaries options
• a permanent client station, and an Open Client station (free connection from any computer)

 
The OFS server was used instead of Topkapi’s Modbus IP protocol, as this allows the programmer to work in Unity with "non located" variables (no physical address to be allocated to each variable).

For Laurent PONCELET, an object-oriented approach in automation and supervision is a major technological leap, and he no longer believes he could implement new major projects without these benefits. Let’s see what this means in concrete terms.
 

Linking Unity and Topkapi for efficient data processing

In the Premium controller, 11 types of structured data items have been defined (here we mention only variables used in supervision): motor, valve, phase control, etc. The most complex include embedded structures (for example command and status variables for a valve) to facilitate management. The controller programme includes declaration of instances of each type, 102 valves, 50 phase commands, 17 motors, etc.

When the link between Unity and Topkapi opens, the latter integrates automatically to the supervision application the types of structured data and instances of variables, whether structured or elementary. Modifying types in Topkapi is not required, but an editor allows extending them with processes performed by the supervisor.

The practical analysis of the supervision database shows the following elements:

• the application comprises 8876 elementary variables
• it contains 288 structured objects retrieved directly from the controller program for a total 8231 elementary variables
• the remainder, i.e. 645 elementary variables, was generated by the link with Unity (except a dozen internal variables specific to supervision)
• all 11 of structured data types represent, including the embedded sub-structures, a total 227 elementary variables. 

When summarising the setting operations, using a classical method, we would have to:

• Instantiate about 8876 elementary variables in the controller
• Recreate – or in the best case import with more or less easy operations on files – these 8876 variables into supervision, and adapt the process performed by supervision for each of them
• Check each of the 8876 variables individually

With Unity and its link to Topkapi, the work required consists in:

• Creating the structures in Unity (227 elementary variables)
• Instantiating 933 variables in the controller (645 elementary variables and 288 structured objects)
• Integrating information with supervision (direct link by wizard, without data handling)
• Adapting the processes of the 645 single variables and 227 elementary variables of structured objects
• Checking individually the 645 variables and 288 structured objects; for a structured object, just check one single instance in detail, then only one of the single elementary variables of each object.

The summary of the operation is:

• Using classical methods, the 8876 variables must be instantiated and checked
• Using the TOPKAPI-Unity coupling, instantiate and check 645 elementary variables, 227 elementary variables of the object types and 288 structured objects, i.e. 1160 basic components.

Finally, processing the database means processing a total 1160 basic elements, instead of 8876.
Forgive us for omitting details, rationalisation constraints or inheritance benefits in object-oriented design, but the figures speak for themselves, and show clearly the benefits provided by this approach.
Hours, even days, of copying/pasting and handling of sterile data are saved, as well as proof checking to eliminate human error.

In addition, the definition of typical objects can be reused from one project to another, without being frozen, as these objects may change during the project without damaging the work already done: the initial organisation effort provides instant return on investment, but is also a capital offering extensive profit over time.