Digital input/output (DIO).
Digital input/output (DIO)
Built around simple relays
A digital signal is a signal that exists in one of two states: high or low, open or closed, on or off. A digital input/output (DIO) device is hardware that sends or receives these digital signals. DIO devices are usually built around simple relays such as reed relays. These relays are normally open but close when power is sent to them. When the relay closes, it sends a signal that communicates a message or triggers another device.
DIO devices can be either input only, providing input from sensors; output only, sending signals to activate a device; or bidirectional, providing both input and output signals.
These are some of the applications that use DIO: