On any railway system an interlocking system ensures that rail traffic can pass safely along a section of track. The track is monitored for passing traffic and at crossing points; this information is then used to control signalling. Protocols like MicroLok® II from Ansaldo are used to transmit this critical data.
Microlok II is a serial protocol so when many device controllers are used the cabling requirement can be significant. Serial solutions are point to point so a cable break will always cause a network failure.
Any trackside installation must be reliable even though the environment is hostile to data communications equipment. EMC levels can be high as many trains are powered electrically, vibration caused by passing trains is significant and temperatures in trackside cabinets can vary considerably over a year.
The Microlok II protocol is a serial protocol designed to transmit messages from one Microlok II controller to another however the specification does allow for it to be transported over a IP network.
By using a converter to encapsulate the serial data in UDP packets the protocol can be transported over an Ethernet network. Ethernet networks can off course run resiliently ensuring communication even in the event of a cable failure.
In WeOS we have a comprehensive Microlok II gateway solution that can handle up to 64 addresses. There is also support for Hot / Standby configuration using heartbeat signal, this provides a resilient channel when controllers are in hot standby.
The inbuilt I/O port can be configured as an alarm output when session timeout occur.
WeOS do not only support the Microlok II protocol, with the layer 3 solutions we you can also use dynamic routing and port based firewall solutions.
Westermo products are incredibly robust. 3:rd party type test according to trackside signaling standards IEC 62236-4:2008 & EN 50121-4:2006 are available on all Westermo units supporting Microlok II. Units will also operate from -40°C to +70°C.
Roger S. Evans
Sales, Westermo North America