Introducing GuardLogix safety controllers

With the launch of the (Bulletin 1756) GuardLogix controller in 2005, the ControlLogix platform supported both standard and safety system control in the same chassis. The GuardLogix controller system is designed for use in safety applications, including SIL 3 (IEC 61508) and applications up to and including PLe/Cat.4 (ISO 13849-1).

The GuardLogix safety controller is part of a failsafe (de-energize to trip) system. This means that when a fault is detected, all of its outputs are set to 0. In the event of a faulty input or input module, the GuardLogix safety controller automatically sets any input values associated with them to 0. The Series 6 (L6), Series 7 (L7), and Series 8 (L8) controllers are all available in the GuardLogix form factor.

Physically, the GuardLogix controllers are usually installed in pairs—the primary controller and the safety partner controller. GuardLogix controllers closely resemble normal controllers, except they are typically red. GuardLogix controllers are only supported in version 18 and higher of RSLogix 5000 and Studio 5000 Logix Designer. When programming safety-related functions, GuardLogix only supports the Ladder logic programming language. However, GuardLogix controllers are fully capable of performing non-safety related functions using the other IEC languages, similar to a normal Logix controller.

In the next section, we will briefly touch on the extreme environment controller series of ControlLogix processors, which are designed to withstand harsh operating conditions.