SDI12 basic command set
ReferenceThe SDI12 command set includes the basic command set as specified by the standard (i.e. V1.1, V1.2, V1.3, V1.4, etc) as well as extended commands which may be included by the manufacturers to add special functionality which is not part of the standard. A common use of the extended commands are to include calibration information. This page reviews the basic command set, relative to the version that it was included in, as well as an introduction of the extended commands
SDI12 Basic Command Set
| Name | Command | Response | Notes |
|---|---|---|---|
| Break (wake up) | - | None | v1.0. To wake from sleep |
| Acknowledge Active | a! | a | v1.0. Testing |
| Send Identification | aI! | allccccccccmmmmmmvvvxxx...xx | v1.0. Check if the right sensor is connected |
| Change Address | aAb! | b | v1.2. Change sensor address |
| Address Query | ?! | a | v1.2. Who is connected? Only works for one sensor |
| Start Measurement | aM! | atttn | v1.0. |
| Start Measurement and Request CRC | aMC! | atttn | v1.3. |
| Send Data | aD0! .... aD9! | a | v1.0. |
| Additional Measurements | aM1! ... aM9! | atttn | v1.0. |
| Additional Measurements with CRC | aMC1! ... aMC9! | atttn | v1.3. |
| Start Verification | aV1 | atttn | v1.0. |
| Start Concurrent Measurement | aC! | atttn | v1.2. |
| Start Concurrent Measurement with CRC | aCC! | atttn | v1.3. |
| Additional Concurrent Measurements | aC1! ... aC9! | atttn | v1.2. |
| Additional Concurrent Measurements with CRC | aCC1! ... aCC9! | atttn | v1.3. |
| Continuous Measurements | aR0! ... aR9! | a | v1.2. |
| Continuous Measurements with CRC | aRC0! ... aRC9! | a | v1.3. |
| High Volume Commands | aHA! (ASCII) aHB! (Binary) | atttnnn | v1.4. Allows up to 999 parameters to be returned from a sensor |
| Metadata Commands. Add I to most measurement commands | aIM! | atttn a,field1,field2,field3; | v1.4. Provides meta data information about the measurement, ie: field1 may be PR, field2 may be mm, field 3 may be precipitation rate per day |
Extended Command Set
| Name | Command | Response | Used by |
|---|---|---|---|
| Store one calibration | aXSETVAR[m,p]=VAL! | aXACK | Vegetronix |
| Retrieve string of the last error | aXER! | aXER BAD COMMAND | Vegetronix |
| Set sensor warm up time | aXW[ms]! | aXACK | Vegetronix |
Version History
You can view and download the SDI-12.org archives at http://www.sdi-12.org/archives.php. The table above identifies the standard at which the basic command was introduced
- Version 1.0 was released in October 1988.
- Version 1.1 was released in July 1994.
- Version 1.2 was released in April 1996
- Version 1.3 was released in
- Version 1.4 was released in May 2017
[…] This was introduced in Version 1.2 of the standard as a basic command, for more details refer to www.sdi12.com/sdi12-basic-command-set/. An example of this […]