To successfully utilize Ethernet in automated environments, the stringent demands of such applications regarding performance, flexibility, availability, and determinism must be met. Especially in markets where high cycle time is essential for determining application quality, network performance is critical.
An example from an industrial setting illustrates the issues at hand: in an application in the packaging machine market, conventional standard Ethernet switches were initially used in networked modular machines, as it appeared that the network speed in this segment was sufficient to adequately control and manage multiple units, I/O, and HMIs for visualization and operation. To achieve vertical and horizontal integration, the machine modules were connected to devices in other modules via external switches and also to the company network.
From Theory to Practice:
However, in actual practice, problems arose despite careful planning. The controller repeatedly reported network errors at irregular intervals, forcing machines to stop and restart. These errors are particularly serious when no obvious cause can be found, but high availability is absolutely essential. Naturally, automation system operators are very keen to eliminate these errors.
HARTING's Solution:
After considerable effort, the solution was found in implementing a HARTING Fast Track Switch (FTS). The FTS records automation data and sends essential data with high priority and in accelerated mode, independent of the rest of the network traffic, thus ensuring that control signals are always received on time.
By using fields defined in the switch heads, the Fast Track Switch identifies an EtherNet/IP or PROFINET frame, for example. Instead of processing this data in the usual "store and forward" mode, the switch enters "cut-through" mode, resulting in a significant performance increase. Furthermore, automation frames can take precedence over non-automation frames if the latter obstruct the passage of high-priority data in the Fast Track switching. Thanks to this concept, Fast Track Switches offer the high-performance solutions demanded by the packaging industry. Fast Track guarantees the required transmission times for automation data and, therefore, ensures availability.
Author:
Anja Dienelt, Product Manager ICPN, Germany, HARTING Technology Group,
