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Reply To: Hydros 21/Decagon CTD: reading error

Home Forums Environmental Sensors Hydros 21/Decagon CTD: reading error Reply To: Hydros 21/Decagon CTD: reading error

Shannon Hicks

    We’ve seen this behavior with some of the new CTD sensors as well.  It seems that when you give it a new address using the b_address_change sketch, the sensor needs to be told the new address more than once in order for it to actually make the change.  Meaning, run the sketch and observe the text on the Serial Monitor.  For a new sensor it will say sensor found at address “0”.  Type “1” into the text box and press Send.   It’ll then say the sensor is now found at address “1”.   However, you should do it at least a few more times.  Enter “1” into the text box again and press Send.  It should say sensor found at address “1” again.  Try it at least 3 or 4 times, and then you should be able to unplug the sensor, upload your logging sketch, and the sensor will be found at address 1.

    You should also make sure you’ve updated you libraries files recently.  The new version of the CTD sensors required a slight change in the SDI-12 protocol instruction timing, and those changes are incorporated in the latest version of the EnviroDIY SDI-12 library.  You can either update just that one folder, or all of them using the EnviroDIY Libraries zip file found at https://github.com/EnviroDIY/Libraries

    If you’re still using an SDI-12 library version from prior to April of this year, it won’t work with the new CTD sensors and you’ll get -9999 for all parameters even if you’ve got the correct address programmed to the sensor.