PNML based composition in non-autonomous Petri net models

The Petri Net Markup Language (PNML) allows the specification of Petri net models based on their primitive elements: places, transitions, and arcs. This paper proposes a complementary way to define non-autonomous Petri net models, based on model addition. The net addition operation is applied at two levels: the structural level (related with the autonomous part of the Petri net model) and the annotations level (related with the non-autonomous part of the Petri net model, and supporting representation for input and output signals and events). This approach allows the construction and modification of Petri net models in a flexible way supporting not only modular composition, but also model modifications. The net addition operator was implemented as a tool and integrated in a framework allowing graphical editing of nets and compositions, as well as automatic code generation to C and VHDL and deployment into implementation platforms, such as microcontrollers and FPGA (Field-Programmable Gate Array). The paper illustrates the application of the net addition operation to an example of a controller for an automation system.