Ethernet switch features GPS time stamping

A Westermo Data Communications product story

Edited by the Engineeringtalk editorial team Apr 29, 2004

The new OnTime T-208 industrial Ethernet switch offers true network determinism, highly accurate sequence of events recording and high-speed fault recovery.

The new OnTime T-208 industrial Ethernet switch offers true network determinism, highly accurate sequence of events recording and high-speed fault recovery.

The T-208 is an eight-port device that further enhances industrial Ethernet networks by using NTP/SNTP.

NTP/SNTP allows SNTP packets to be time stamped to an accuracy of 1us or better using a GPS (Global Positioning System) receiver attached to the switch.

Precision time stamping is critical in applications where very high accuracy is required to provide a reliable SOE (sequence of events).

This allows events to be traced back to an originating source.

The T-208 incorporates two priority queues that are designed to ensure that the network data is deterministic.

This is achieved by implementation of Layer 2 and Layer 3 priority tagging.

In addition head of line blocking prevention ensures that the switch does not become congested by low priority data.

The T-208 is unique in being able to prioritise data streams in a redundant network.

This allows engineers to design a reliable, deterministic network while prioritising data into low and high priority queues.

The T-208 also enables Ethernet networks (both copper and fibre) to be constructed in a high-integrity redundant ring configuration that recovers ultra-fast after network failures resulting from infrastructure faults such as cable breaks.

Up to 200 T-208 units can be placed in the ring, allowing, in theory, redundant networks of up to 4000km rings in circumference to be created.

Redundant rings rely on the fact that if a breakage occurs the ring changes into one multi-drop string, which continues to operate while the ring is restored.

However, when a failure is detected two actions must take place - the address memory of every switch in the ring must be purged of the old ring configuration and the new configuration is relearnt as communications are re-established.

In normal Ethernet networks this can take minutes; the T-208 adopts special strategies to ensure that recovery is achieved within 30ms.

This recovery time, says Westermo, is among the fastest available today and enables the construction of large Ethernet LANs and WANs servicing critical industrial applications.

The T-208 supports the long cable specification that allows copper cables to extend up to 150m; in addition MDX/MDIX technology ensures that standard straight through cables can be used even with switch to switch or uplink connections.

A wide input voltage range (19-72V DC), dual power inputs, polarity protection and very low power consumption of less than 10W allows the T-208 to run from batteries and permanent power supplies.

Although the T-208 supports auto negotiation on all ports the units also have a useful push button control panel to allow individual ports to be configured for a particular negotiation thereby allowing simple connection to some legacy equipment.

A "military" design and an operating temperature range from -40 to +65 C makes the T-208 ideal for use in arduous, critical applications in industrial environments.

A Windows configuration tool is used to configure the device and SNMP network management services are incorporated as standard.