In-Situ RDO-Pro/Blue X2 Integration Guide

The In-Situ RDO-Pro-X and RDO-Blue dissolved oxygen (DO) sensors accurately measure DO and temperature. These sensors are compatible with the X2 data logger via the RS-485 Modbus communication protocol. Below is information on the settings and wiring required to integrate these sensors with an X2 data logger.

Note: Ensure to install the DO cap onto the sensor before deployment. DO cap installation instructions can be found in the user manual for each respective sensor.

RDO-Blue Manual

RDO-Pro-X Manual


Figure 1: In-Situ RDO-Pro-X Dissolved Oxygen sensor.


Wiring for Software Communication

These sensors can be configured using the Win-Situ 5 software and communication device kit provided by In-Situ. For an RDO-Pro-X or RDO-Blue sensor connected via a flying lead cable, follow the wiring overview on page 8 of the RDO-Blue manual to connect to the communication device kit. If the sensor has a NexSens UW8 plug connection, a UW-FLxR can connect to the In-Situ communication kit following the wiring table below.

Communication Kit Color IndicatorSignalNexSens UW-FLxR Wire Color
BlueRS-485 A (+)Green
GreenRS-485 B (-)Blue



NexSens UW8 Connector Wiring & Pin Information

In the event of connecting a NexSens UW8 connector into an external device that is not an X2 data logger, below is the pinout of the NexSens UW8 connecter, along with the signal associated with the communication, ground, and power pins from the sensor.

NexSens UW8 plug pinout.


NexSens UW8 Pin NumberSignal



Configure Communication

  1. Connect the USB cable to a PC with the Win-Situ 5 software.
  2. Open the Win-Situ 5 software.
    1. Go to Preferences | Comm Settings to insert the correct COM port and address for the sensor for the initial connection.
    2. Brand new sensors should have address 1 and Even parity.
    3. Click the checkmark at the bottom once the proper changes are made.

Default communication settings for initial connection.


  1. Go to File | Connect to connect to the device.
  2. Travel to the tools icon once connected to the device and click on the Modbus Setup. Change the parity (and address if it interferes with other sensors) to None. 
    1. It is recommended to change the SDI-12 address to ensure there is no interference with other SDI-12 sensors.

Modbus settings setup.


Change parity to none.


  1. Now that the communication settings have changed, the software will disconnect from the sensor unless changes to the default settings are made.
    1. The sensor is now ready for detection on the X2 data logger.


X2 Script Information

The X2 data logger includes a pre-loaded RDO-Pro/Blue script. Use the CONNECT software to enable the script for sensor detection.

Configure Sensor Scripts

X2 Script NumberCommunication ProtocolBaud RatePower TypeWarmup Period (sec)Frame



Script Parameters

Dissolved Oxygenmg/L
Dissolved Oxygen% Sat

*If the DO cap for the sensors are not installed, both dissolved oxygen parameters will read zero.