Safety controller

A safety controller comprising:

• a basic module;
• one or more extension modules;
• and
• a mother board provided with an extension slot for connecting the modules by a bus;
• wherein
• an input extension module which is one of the extension modules includes one or more input terminal sections capable of connecting one or more safety switches and an input circuit for receiving safety input signals from one or more external input terminal sections,
• an output extension module which is one of the extension modules includes an external output terminal section which can be connected to an output control system of a dangerous source and an output circuit for transmitting a safety output signal to an external output terminal section, and
• the basic module has an operation program storing part for storing a safety operation program for defining the relation between the state of a safety input signal and the state of a safety output signal on each of types of predetermined safety switches, a type-of-switch setting part for setting an external input terminal section and the type of a safety switch to be connected to the external input terminal section, and an operation program executing part for selecting a safety operation program corresponding to the type of the switch set by the setting part among a plurality of safety operation programs stored in the operation program storing part and executing the program for the external input terminal section set by the setting part.