The purpose of the discrete output module is to control field devices. Discreet (digital) output devices only have two states:  On or Off

The discrete output module requires power from an external source. When a 1 is placed into the output tag of the ControlLogix (in run mode), a status light is energized on the module, and a connection is made between the source, and the corresponding output terminal.  An example of a Controller Tag for an output module would be:  Local:6:O.Data.0  (The Local Chassis (where the processor resides), Slot 6, Terminal 0.

Examples of output devices include: lights, solenoids, motor starter coils, and contactors. If you have an inductive load as the output, be sure to use the proper surge suppression.

Many different output modules are available, such as Triac, Transistor, Relay, Isolated, and Diagnostic modules.  Don’t forget that most output modules with solid state switches, such as the Triac, will require a minimum load due to leakage current.