Why is a YSI ODO RTU Not Gathering Readings?

The YSI ODO RTU X-Series Integration Guide outlines the required process for integrating YSI ODO RTU sensors with NexSens X-Series data loggers. If the sensor is not providing values after following the guide, below is a list of common reasons.

Issues with Gathering Readings

  • Issue #1: Two or more sensors connected to the data logger have the same Modbus address.
    • Explanation: NexSens X-Series data loggers can only read measurements from a Modbus RS-485 sensor if it has a unique address. If another connected sensor using the Modbus 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 Modbus addresses for each sensor in their respective software.
  • Issue #2: There is a gap in the registers outlined in the user-generated script.
    • Explanation: The user-generated script must have a continuous register request from the 1st to the last parameter. The beginning register address should always start at 0 for ODO saturation (%), and each subsequent parameter must be requested until the last available parameter. A gap in the register request will respond with erroneous data.
      • Solution: Review the user-generated script to ensure the parameter list and register request matches the parameter order in Section 5.3 Data of the YSI ODO RTU Sensor manual.