November 8, 2015 Leave a comment
After some delay, the SDI-12 USB adapter is finally here:
This adapter is extremely easy to use. Just connect it to your PC and SDI-12 sensor. Then you can use any serial monitor or terminal emulator program to talk with your sensor. Just open the serial port at 9600 Baud rate. You can start by sending device identification command such as ?!. You will see a response from your sensor, which is the one-character address of your sensor. If you have not set its address, it is most likely to be zero (0). Then you can use 0I! to find out the manufacture and model of your sensor, before getting measurements from it. Getting measurement is easy as pie. First send 0M!, then wait for response. Then send 0D0! to fetch the measurements.
For PC users, I even wrote a data logger script that can automatically log data using the popular Tera Term program. You can choose sensor address, total number of data points, delay between points, and time zone when logging, then the program will keep logging data. The following is a screen grab of Tera Term. The sensor is a Decagon 5TM soil temperature and moisture sensor. The address is one (1) and the returned values are relative dielectric permittivity and then temperature in Celsius.
Once you get data logging going, you can import the .CSV file into your Excel and plot it. You can choose a proper refresh rate so your data and plot are up to date when you look at them.
I’m still ordering more circuit boards but should be able to sell these on my inmojo.com store starting now. There is even a quantity discount if you need 10 or more.