PLC (Programmable logic controller) systems offer the high-speed response and reliability required in closed loop control systems, typically in mechanised manufacturing, construction and machining. This dependability is particularly important with fast-moving equipment and critical infrastructure applications. Key features when specifying PLCs include arithmetical processor performance, accuracy and clock speed. Other desirable points include scalability, ease of integration, fail-safe operation and internal diagnostic routines. Siemens is a respected leader within the sector, offering top-quality PLC hardware. Alternatively, Wago is a medium-sized manufacturer and automation specialist with offices in Germany, the UK and worldwide - including production facilities on every continent. This brand includes PLCs designed for mining and offshore marine use, in harsh operating conditions. Programmable logic controllers (PLCs) are becoming ever more cost-effective and compact, with surprisingly small footprints, yet rich in features such as 64-bit processors and advanced encryption (SSH or SSL/TLS). Some units also feature built-in security, web servers and a network firewall, while starter kits are convenient for initial installations.