Safety related control systems for railway signalling applications with a safety PLC

Nowadays, there are available on the market not only standard PLCs (Programmable Logic Controller) but also safety PLC´s. These are primarily designed for industrial applications. Their guaranteed safety properties, however, enable to be used in applications, in which the usage of PLC has not been common until now. The aim of this article is to focus on problems related to the usage of safety PLC in railway signalling systems.