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The Comtrol HEA is used by Westinghouse Rail
Systems Limited (www.westsig.co.uk)
in support of their contract to supply Bombardier Transportation with
Signalling, Train Control and Train Supervision systems as part of a
Bombardier contract with the erstwhile
Metronet consortium, now replaced by Transport for
London (TfL). The Bombardier contract encompasses Rolling
Stock supply, refurbishment and maintenance, and Signalling Upgrade projects for
Infraco BCV and Infraco SSL under the London Underground Public Private
Partnership (PPP) scheme. The HEA function The HEA is an rack-mounted Hitachi SH2DSP-based device running the eCos operating system that provides a gateway between legacy HDLC-connected WRSL equipment and a state-of-the-art Ethernet/TCP-connected control and monitoring system. Connecting up to 8 HDLC point-to-point links onto a single 10/100-baseT Ethernet, the HEA simplifies the deployment of migratory systems and reduces overall system cost. |
SystemSoft's Role Working with Westinghouse staff and the hardware designers to ensure an integrated approach, SystemSoft undertook all software development for the system and brought the project home against tight time and budget targets. Host System Software It was a requirement that the host system would require no HEA-specific driver components, so a TCP/IP interface was chosen. This allowed future HEA deployments to be made in non-Windows environments, allowing HDLC data-communications to be achieved by controlling the HEA through a sockets interface. SystemSoft defined a control-and-data protocol that offered management and data transfer capabilities to application software running in the host PC. provision is made for hot-standby control, with keepalive and watchdog mechanism ensuring that Host-HEA communication is never lost without notification. . |
To illustrate the controlling protocol, SystemSoft developed the test software in 'C#', the langauge chosen by Westinghouse for its application development.On-board software As the HEA was hardware-derived from an earlier product, the CPU and the OS were fixed as an Hitachi (now Renesas) SH2 and eCos. SystemSoft generated on-board firmware that executed machine diagnostics and perform the Ethernet-HDLC conversion. This is a signle, multithreaded, application loaded on completion of diagnostics, and runs until the device is powered down, or reset,. The HDLC faming and bit-stuffing is performed by DSP-controlled line interface hardware, but the HDLC protocol is operated by the SystemSoft-originated firmware, which also interfaces to the eCos-provided TCPIP stack. Subsequent Development Following initial release, an enhancement request was made to add Asynchronous communications capability to the HEA. SystemSoft undertook this enhancement, integrating the additional capability without compromising the original HDLC capability |
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