Asynchronous Data

The isochronous phase of the POWERLINK cycle for time-critical payload data transfer is followed by the asynchronous phase, which completes the cycle. In this phase, non-time-critical data packets can be transmitted in standard Ethernet frames. Any type of data can be transferred during the asynchronous phase, e.g. service data objects (SDOs) for device configuration and diagnostics, application data such as surveillance camera feeds and even protocols like TCP/IP for device configuration or maintenance from a web browser. This also provides a way to connect nodes that are not real-time capable to the network in addition to integrating components or plant segments equipped with other fieldbus interfaces. In the latter case, devices are connected to a POWERLINK node via a gateway; their non-POWERLINK fieldbus data is then transmitted in the asynchronous phase of the POWERLINK cycle. This mode of data transfer is extremely vital for hot plugging, in which new devices or replacements identify themselves by sending their device data to the managing node during the asynchronous phase.