Train Simulator Controller: TPWS Control Panel

As I continue to build my adaptation of a UK Class 800 dashboard and cab for train simulation, I often need to create replicas of equipment from scratch, when it is impossible or infeasible to get the real thing. Indeed, one of the first components I explored for my train simulator was a from-scratch master controller, the combined throttle and brake used in some modern passenger equipment. One important panel interfaces with the Train Protection and Warning System (TPWS), which automatically stops a train if it passes a stop signal without permission (SPAD), exceeds permitted speeds in several situations, or approaches buffers at end-of-track too quickly. For the curious, the linked Wikipedia article gives great detail, but for the purpose of this blog post, the control panel provides important information to the driver and allows them to release an automatic emergency brake application. Alongside the Automated Warning System (AWS), TPWS provides similar protections to Positive Train Control (PTC), preventing trains from entering blocks without permission, overspeeding through sharp curves, and overrunning end-of-track at speed.

TPWS panels are available in a “standard” version, with two buttons and one illuminated indicator, or an “enhanced” version, with five buttons (four of which illuminate) and one illuminated indicator. The Class 80x trains are fitted with the enhanced version, shown here in situ in 802016, with red and yellow buttons at upper left of panel:

The panels can be purchased from Thales, albeit for a large price and generally not by private individuals. Therefore, I set out to recreate the panel. Thanks to knowing what make and model of buttons are used in the panel, I was able to deduce the overall dimensions and layout from photographs, and used SendCutSend to get a piece of mild steel cut and powder-coated to spec. When it arrived, a test-fit showed that the requisite buttons fit snugly into their apertures:

As with many of the other components of my train simulator, I sourced both new and used button components, gradually collecting everything I needed to illuminate the buttons that need it (at 12V DC), register button presses from the buttons that need it, and in this case, cover the one button (Brake Release) that should never be accidentally pressed - and may even be fitted with an anti-tamper seal if needed. As with my other components, I wired the buttons and indicators up to one of my CAN bus transceiver boards, now with a new I/O Expander daughterboard that allows robust, debounced inputs and low- to high-current outputs to be connected to the CAN bus board.

When completely wired up, I was able to test the result with my on-computer Train Simulator interface software, illuminate the indicators, and register button presses. The final missing piece is to print the necessary labels on the powder-coated metal, which will be covered in a future blog post.