> For the complete documentation index, see [llms.txt](https://docs.yudash.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.yudash.com/pf/si/sdi12.md).
# SDI-12
SDI-12 is a digital communication interface commonly used with environmental, hydrology, agriculture and weather sensors.
YuDash data loggers with SDI-12 support can communicate with compatible SDI-12 sensors, acquire multiple variables from a sensor and map the returned values to user-defined parameter names.
Typical applications include:
* Soil moisture and soil temperature
* Water level and hydrology sensors
* Water-quality instruments
* Meteorological sensors
* Agriculture and irrigation monitoring
* Multi-parameter environmental probes
On supported FELYX models, SDI-12 is available as a dedicated sensor interface.
### How SDI-12 works in YuDash devices
A typical configuration consists of:
**SDI-12 Sensor → YuDash Data Logger → Variable Mapping → Data Logging / Cloud / Local Monitoring**
Each connected sensor is assigned an **SDI-12 address**. The YuDash device sends the configured measurement command to the sensor and reads the returned measurement values.
The individual returned values can then be assigned meaningful variable names.
### SDI-12 Sensor Connection
Connect the SDI-12 sensor to the supported YuDash device before starting configuration.
A typical SDI-12 connection includes:
* **Power** — sensor supply from the device, where supported
* **GND** — common ground
* **SDI** — SDI-12 data line
The example below shows an SDI-12 soil-moisture sensor connected to a YuDash FELYX data logger.
> Always refer to the sensor datasheet and the product wiring guide for the exact terminal assignment, supply requirement, and wire colors.
## Configuring an SDI-12 Sensor
{% stepper %}
{% step %}
### Enable the SDI-12 feature
Open **Device Settings** and locate **Feature Settings**.
Enable **SDI-12** for the device. This activates the SDI-12 sensor interface in the runtime configuration.
{% endstep %}
{% step %}
### Open the SDI-12 Wizard
Go to **Sensor Settings** and select:
**Open SDI-12 Wizard**
This opens the **SDI-12 Sensor Manager**, where connected SDI-12 sensors and their returned variables can be configured.
{% endstep %}
{% step %}
### Add or select a sensor
In the **SDI-12 Sensor Manager**, add a new sensor or select an existing sensor from the list.
Configure the sensor settings:
* **Address** — SDI-12 address assigned to the sensor.
* **Label** — optional descriptive name for the sensor.
* **Measure Cmd** — measurement command used to request data from the sensor. `M!` is the standard measurement command shown in this example.
* **sdi12VarCnt** — optional variable-count setting. Leave blank when all returned variables are to be processed.
Under **Variable Mapping**, map the values returned by the sensor to YuDash variables.
For each variable, configure:
* **Var Name** — name used for the parameter in YuDash.
* **Factor** — scaling multiplier; normally `1` when no additional scaling is required.
* **Unit** — engineering unit, where required.
* **Description** — optional description of the parameter.
The **IDX** represents the sequence position of the value returned by the sensor.
In the example shown, one SDI-12 sensor returns five parameters:
1. Volumetric water content
2. Soil temperature
3. Relative permittivity
4. Bulk EC
5. Pore water EC
Select **Save & Close** after completing the sensor configuration.
{% endstep %}
{% step %}
### Configure the sensor
Return to **Device Settings** after saving the SDI-12 configuration.
Follow the standard YuDash configuration sequence:
**Update and Preview → Write Device Config → Reboot**
The new SDI-12 settings become active after the device restarts.
{% endstep %}
{% step %}
### Verify SDI-12 Data
After the device restarts, open the **Live Dashboard**.
The configured SDI-12 variables should appear under **Sensor Data** with their current values.
The **Device Run Status** can also be used to confirm communication with the sensor. During normal operation, the log will show the SDI-12 sequence, including sensor detection, measurement, reading and processing of the returned values.
This provides a quick way to verify that:
**Sensor detected → Measurement completed → Values read → Variables available**
{% endstep %}
{% endstepper %}
***
## SDI-12 Tool
YuDash also provides an **SDI-12 Tool** for sensor commissioning, testing and troubleshooting. It can be used independently to communicate with SDI-12 sensors before or during field installation.
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