Publicação
Improving flexibility in a real-time fieldbus network
| Resumo: | A typical approach to real-time fieldbus arbitration is the use of an off-line scheduler that generates a cyclic static table containing the allocation of bus-time-slots to the transaction of process control variables. This approach, used in the FIP fieldbus (Factory Instrumentation Protocol), is highly inflexible in the sense that any system changes, such as adding a sensor, requires the interruption of the fieldbus operation. In this article we propose the use of a planning scheduler to overcome such inflexibility. This scheduler compromises between the advantages and disadvantages of typical dynamic and static scheduling. A sufficient schedulability condition is also presented that incurs minimal run-time overhead and, therefore, is suited to on-line analysis.The possibility of using the planning scheduler within the FIP context is also described resulting in a compatible FIPlike fieldbus. |
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| Autores principais: | Pasadas, Rosa |
| Outros Autores: | Almeida, Luís; Fonseca, J. Alberto |
| Assunto: | Fieldbus arbitration Planning scheduler |
| Ano: | 1997 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Instituição associada: | Universidade de Aveiro Departamento de Electrónica Telecomunicações e Informática |
| Idioma: | inglês |
| Origem: | Electrónica e Telecomunicações |
| Resumo: | A typical approach to real-time fieldbus arbitration is the use of an off-line scheduler that generates a cyclic static table containing the allocation of bus-time-slots to the transaction of process control variables. This approach, used in the FIP fieldbus (Factory Instrumentation Protocol), is highly inflexible in the sense that any system changes, such as adding a sensor, requires the interruption of the fieldbus operation. In this article we propose the use of a planning scheduler to overcome such inflexibility. This scheduler compromises between the advantages and disadvantages of typical dynamic and static scheduling. A sufficient schedulability condition is also presented that incurs minimal run-time overhead and, therefore, is suited to on-line analysis.The possibility of using the planning scheduler within the FIP context is also described resulting in a compatible FIPlike fieldbus. |
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