About Safe Computers

Failures of safety-critical electronic systems can result in loss of life, substantial financial damage or severe harm to the environment.

One of the key design elements of a safety-critical system is redundancy. The complex architecture of such systems usually requires equally complex software, resulting in a very time-consuming and expensive development process. The design of MEN’s safe computers avoids this problem by keeping the special requirements of a redundant setup entirely on the hardware level – to the application, the single-board computers A602 and D602 appear as regular single-CPU cards with just one main memory rank despite their triple-redundant architecture. Behind the scenes, a 2-out-of-3 voting mechanism keeps the boards’ three PowerPC® CPUs in lockstep and monitors all accesses to the main RAM, thus avoiding the negative effects of single-event upsets (SEUs) – a common problem for avionics applications caused by cosmic radiation. The voters are implemented as IP cores in a safe FPGA.

Another important design goal for these boards were predictable execution times. A safety-critical system must react to an external event within a defined time, and this reaction time must be met even under worst case conditions. The A602 and D602 are designed for strictly deterministic operation without interrupts and DMA to avoid compromising the system’s reaction time.

MEN is certified to EN/AS 9100 and IRIS. In addition to this, both of MEN’s safe computers have been developed according to DO-254 (avionics) and EN 50129 (railways). The D602 was originally designed as the core of the freight load system of the Airbus A400M, and is now available as COTS hardware for CompactPCI® systems. In addition, the boards comply with environmental standards DO-160 and EN 50155. They are qualified for operating temperatures of -40 to +50°C, at altitudes up to +20,000 m. With conduction cooling, they can tolerate up to +70°C. Given this design background, certification according to the most stringent safety levels – SIL 4 in railway or DAL-A in avionics applications – can be achieved.

Typical Applications

Safe computers from MEN are usually used in avionics or railway applications requiring particularly high reliability.

Avionics examples

Railway examples