Fast-recovery switch keeps industrial Ethernet up

A Westermo Data Communications product story

Edited by the Engineeringtalk editorial team Sep 2, 2003

The OnTime R-208 Ethernet switch enables high-reliability, fast-recovery, redundant ring industrial Ethernet installations, particularly in critical applications.

The OnTime R-208 Ethernet switch enables high-reliability, fast-recovery, redundant ring industrial Ethernet installations, particularly in critical applications.

R-208 enables Ethernet networks (both copper and fibre) to be constructed in a high-integrity configuration that recovers ultrafast after network failures resulting from infrastructure faults such as cable breaks.

Up to 200 R-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 multidrop 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 R-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.

R-208 is an eight-port device with two allocated to the ring.

The other six ports are used to connect other Ethernet equipment to the ring.

R-208 incorporates two priority queues to ensure that network data is deterministic.

Head-of-line blocking is also used to ensure that the switch does not become congested by low priority data.

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

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

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

With the OnTime R-208 Ethernet switch Westermo is making available the industrial SNMP (iSNMP) software suite from COI Software, which allows external systems to collect and interpret raw SNMP data from the R-208.

The iSNMP suite incorporates an OPC DA server, enabling remote OPC client software running in equipment such as HMIs and Scada to collect SNMP data for remote processing and analysis.

The iSNMP suite consists of several applications: Network Analyst performs continuous calculations on the collected data to generate meaningful information such as bandwidth utilisation and error rates; Traps Support allows a device to send data unpolled to signal critical events; an iSNMP Ethernet toolkit called Observer can capture and analyse data, also test the network, allowing maintenance personnel to diagnose and fix network problems quickly.