Digital output modules are commonly found in automated industrial controllers. There are inputs coming from either analog or digital sources. Digital sources are mainly from electromechanical relays, switches, or industrial binary sensors that ‘transmit’ a 24 V for “ON” and 0 V for “OFF”. Outputs are either analog or digital format. For digital output modules, they basically are multi-channel switches that turn “ON” actuators and relays that turn on larger loads. Current drive of each channel can be as low as a few hundred milliamps and as high as several amps.