SDI-12 is a communications protocol for intelligent sensors that typically are used to monitor environment data. Devices and sensors are available from multiple manufacturers.

For detailed information about SDI-12, please refer to http://www.sdi-12.org/

The bus is multidrop, meaning multiple devices can be connected to the same data wire, and because each device is configured with a unique address, the ezeio can individually read data from each device.

The ezeio hardware port conforms to the SDI-12 v1.3 standard, but can also be configured for other purposes via software. The port can be used for example with a GPS receiver to monitor NMEA location messages, or to read certain proprietary protocols. When used in other modes, the standard SDI-12 functionality is not available.

The SDI-12 communications uses a single wire for data going both to and from the device. The devices are usually designed to use very little power, and can be powered directly from the ezeio terminals. Up to nine (9) devices can be connected to the same bus.

We do not recommend using SDI-12 with more than about 60m (200ft) total bus length, although with few devices and good quality wire, longer buses are possible. Please refer to the SDI-12 specification for further details.

Most SDI-12 devices are designed to run on 12VDC. The ezeio can run on other voltages, so please make sure you use an appropriate power source if you are connecting SDI-12 devices.