| which provide meta data information about the measurement, such as the parameter name and units | Power is supplied to sensors through the interface• 3 was released in April 2000 and defines:• 1 was released in 1994 |
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| 2 was released in April 1996 | Applications [ ] The protocol is most commonly supported by hydrographic sensors level and flow , water quality sensors, meteorological instruments, soil moisture and plant physiology |
for binary format which allow up to 999 parameters to be returned from a sensor.
| Communications protocol such as means of establishing contact with a specific address sensor , the measurement command set, sensor response behavior, byte frame format and allowed characters | The standard also specifies a communications protocol that allows sensors to remain in a low-power sleep state until awoken by a serial break signal sent by the master |
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| The data signal, using 5V logic levels, is similar to RS-232 with the same asynchronous byte encoding | The protocol follows a client-server configuration whereby a data logger SDI-12 recorder requests data from the intelligent sensors SDI-12 sensors , each identified with a unique address |
| Electrically the protocol is a three wire digital connection: data, ground and 12 V | 4, with clarifications , was released on January 30, 2021 |
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| History [ ] The first version of SDI-12 was released in 1988 | 4 was made in July 2016 |
The SDI-12 Specification is maintained by a non-profit corporation called the SDI-12 Support Group.