Sensor Troubleshooting

  1. “Any time I try to address my sensors in a terminal program, I get a message saying “SDI12 Failed.”

    1. The best thing that you can do here is get a ProCheck to do the addressing.  Terminal programs have a very short time-out that can be tricky and problematic.  However, if you still want to use the terminal program, here are a few suggestions:

      1. Make sure you have only one sensor hooked up at a time, powered continuously through a 12 V port.

      2. Query the sensor address first using the ?! command. This way you are certain that the sensor is communicating and that you are changing the address of the correct sensor.

      3. Move as fast as possible! The short time-out in terminal programs can be annoying. You must get the aAb! command out quickly or SDI-12 will time-out and the program will show the dreaded “SDI12 Failed” message.

      4. If the program does give you the “SDI12 Failed” message, you need to get the terminal prompt up again. Type the ”sdi12″ command, and (if you are on a datalogger) make sure you get a message asking you what port you want to use. If this message doesn’t show, then you have not actually entered SDI-12.

      5. Try again with a different sensor. We rigorously test our sensors but, unfortunately a bad one escapes from the factory from time to time. Trying again on a different sensor can help you determine if this is the issue. If the problem does not persist when you try on another sensor, come back to the sensor that gave you trouble.

      6. For more help on this, see this application note.
  1. “All of my sensors are sending back bad data.”

    1. Use a ProCheck to check each individual sensor for functionality.  If you find a sensor that is not working properly, remove that sensor from the network and contact Decagon for a replacement.

    2. Your bus is not working correctly. To test this, see section 1 on the Bus Troubleshooting page.
    3. If your bus is working fine and your sensors are working normally, try hooking up just one sensor to your data logger.  If the sensors work when checked with the ProCheck, but not on your data logger, one of three things could be happening:

      1. Your data logger may not be working properly.  Contact your data logger manufacturer to troubleshoot the individual logger.

      2. Your sensor is not connected correctly to the logger.  Make sure that you are powering the sensor through the 12 V excitation port using the white wire, that you are grounding the sensor using the shielded wire, and that your  red wire is connected to a port on your data logger capable of two-way serial communication. Remember, Decagon’s wiring is opposite of that of many other SDI-12 manufacturers. RED is communication, while WHITE is excitation.

      3. Your program is not written properly. Try loading one of Decagon’s example programs without changing anything.  Example programs can be found here. If this program works fine, your program is most likely not working correctly. Contact your data logger manufacturer for programming assistance.