The DO-2 provides 16 normally-open relay circuits for controlling output loads provided by the user. The output points are arranged in two groups of eight points each. Each group has one common terminal. The relay outputs can be used to control a wide range of devices such as motor starters, solenoids, and indicators. Internal fuses protect the DO-2 relay contacts should ratings be exceeded.

The insert in the hinged cover of the terminal strip has circuit wiring information. Circuit identification information can be recorded on the outside surface of the insert. The outside left edge of the insert is color-coded red to indicate a high-voltage module.