Integration of advanced Quality of Service in IEC 61499 based networks

The function block standard IEC 61499 is gaining popularity as a solution for distributed automation systems. Its event-based concept suggests the use of packet-based networks such as conventional Ethernet as underlying communication infrastructure. For such networks, however, proper Quality of Service (QoS) mechanisms are required to ensure adequate network performance. Ideally, these mechanisms must be configured and controlled from the IEC 61499 system both during engineering and normal operation. This paper addresses the problem of fully integrating Ethernet switches into an IEC 61499 system rather than treating them as transparent network components. An analysis of existing QoS support in available devices reveals a large degree of heterogeneity in the implementations that calls for an abstraction layer. This abstraction is introduced by means of a dedicated QoS function block attached to the device which makes the QoS parameters accessible from the function block application layer thus making the device-specific implementation transparent to the IEC 61499 system developer.