Why is an EXO Sonde Not Detecting?

The YSI EXO Water Quality Sondes X-Series Integration Guide outlines the required process for integrating a YSI EXO sonde with a NexSens X-Series data logger. If an EXO sonde fails to detect after following the guide, below is a list of common reasons.

Issues During Sonde Detection

  • Issue #1: The EXO deployment template was not saved properly or loaded onto the sonde.
    • Explanation: NexSens X-Series data loggers can only detect a sonde if a unique SDI-12 address and parameter list are available in the deployment template.
      • Solution: Follow the integration guide to create the template and ensure it is adequately saved before running a new detection.
  • Issue #2:  Two or more sensors connected to the data logger have the same SDI-12 address.
    • Explanation: NexSens X-Series data loggers can only read measurements from a sonde if it has a unique SDI-12 address. If another sensor using the SDI-12 communication protocol has the same address, both sensors will respond simultaneously to commands. Thus, communication will be interrupted as the logger expects a specific response.
      • Solution: Review and adjust the SDI-12 addresses for each sensor in their respective software.
  • Issue #3:  The cable utilized for the sonde is incorrect for the EXO model or wired incorrectly.
    • Explanation: EXO 1 and 2 models require a NexSens UW to EXO Sonde Cable Adapter or a flying lead cable wired into an EXO DCP adapter. The EXO DCP adapter converts the proprietary signal from the sonde into SDI-12 signals. EXO 3 sondes do not require an EXO DCP adapter, as the sonde outputs directly in SDI-12. While the EXO 3 models can work with a DCP adapter, there is potential that the DCP adapter interrupts communication. NexSens produces a UW Sonde Cable Adapter specifically for the EXO 3 model.