Problem:     A major supplier of transit vehicle braking systems needed to update their system electronics to incorporate today's 32 bit microprocessors and modern inter-module communications. The new architecture needed to use as many of the existing peripheral cards as possible. The resulting system needed to have both high availability and high reliability.

Solution:     A comprehensive analysis of the existing system was conducted and problem areas identified. The result was to redesign their Z-80 based central processor card to use an embedded Intel 386. This provided an order of magnitude improvement in computing bandwidth. The analog I/O subsystems were also redesigned to provide substantial improvement in accuracy and reliability. To implement the communications channel that provides redundancy, a LonWorks based twisted pair (FTT-10) network was chosen. The LonWorks gateways that interfaced the existing electronics to the LonWorks network used a shared memory architecture that required no changes to the system bus.

This system was safety critical and all hardware and software were developed under strict development process control and underwent extensive verification and validation. The result was a system that provided a substantial improvement in computational bandwidth and reliability.

Group Alpha was also chosen as the contract manufacturer for the finished product.

Postscript:     After this project was completed, Group Alpha was subsequently contracted to provide custom test equipment for both the car integrator and the final customer. Group Alpha has also provided other communications modules for train braking to be used on other car systems. Our LonWorks subsystems can be found in WMATA, AMTRAK ACELA, and BART braking systems to name only a few.