YSI EXO-Series Sonde X2 Integration Guide

The YSI EXO-Series Sondes are compatible with the X2 data logger using the SDI-12 sensor interface and communication protocol. EXO 1 and 2 models require an external EXO DCP Signal Output Adapter for communication.  Adapters can be installed in an A50 junction box for direct wiring or purchased with the NexSens UW-EXO adapter. NexSens produces a cable for the EXO 3 sonde, which outputs SDI-12 directly. Depending on the installed sensor probes, these sondes can measure a host of environmental parameters selected within the YSI KOR software. Below is information on the settings and wiring required to integrate these sensors with an X2 data logger.

Figure 1: YSI EXO 1 Water Quality Sonde

Figure 2: YSI EXO 2 Water Quality Sonde


Figure 3: YSI EXO3 Water Quality Sonde


Upload a Parameter Template

All EXO sondes used with a NexSens data logger must have a template applied, determining the measured parameters and the order they are logged from the sonde. Upon sensor detection, the data logger will read and save the sonde’s parameter list and SDI-12 address. Thus, any EXO sonde connected to that port on the data logger must have the same parameter list (including the order) and SDI-12 address unless a new sensor detection occurs.

  1. Download and open the YSI KorEXO software and connect the sonde via the EXO USB Signal Output Adapter or a bluetooth connection. Click CONNECT.

KOR software instrument connection panel.


  1. Navigate to the DEPLOYMENT tab. Choose one of the three options to create a parameter template:
    1. Create Template – Create a new template.
    2. Create Template from Sonde – Upload and edit the current template loaded onto the EXO sonde.
    3. Open Template – Upload an existing template to the EXO sonde.

Create or upload a template to the sonde.


  1. In the BASIC DEPLOYMENT SETTINGS, it is recommended to only change the Deployment Template Name and leave all other values as default. The X2 data logger will provide power to the sonde each reading, thus, logging internally is unnecessary.
    1. Note: Since the X2 provides power to the sonde, it is NOT recommended to install batteries. If the sonde’s internal batteries drop to a low voltage, the EXO will continuously reset and will interrupt SDI-12 communication with the data logger.
  2. In the DCP ADAPTER OUTPUT, set the SDI-12 address (1-9) and select the required parameters from the list. Ensure to note the units along with the parameter name.
    1. Review the available parameters for each installed probe in the EXO User Manual from YSI.
    2. Upon sensor detection, the X2 data logger will read the parameter list from the Selected SDI-12 Parameters list.

EXO example parameter template.


  1. In the ADVANCED tab, it is recommended to keep all settings as default. The X2 data logger will provide power to the sonde, which will wipe once before each reading.
  2. Once the template is complete, select SAVE AND APPLY TEMPLATE TO SONDE.
    1. It is not recommended to start internal logging.


Review Parameter Template

After the template is saved, it is recommended to provide at least 15-30 seconds for the sonde to upload the template before disconnecting. To ensure the template is saved correctly, disconnect from the sonde, cycle power (remove power for 30 seconds and then reapply), reconnect to the sonde, go to the DEPLOYMENT tab and select Create Template from Sonde. The template name and parameter list will automatically load from the sonde if the template is saved correctly. If not, load the template again and provide more time after saving to the sonde.


Data Logger Connection

Depending on the EXO model, the sonde will either be connected with an EXO DCP Signal Output Adapter (EXO 1 and 2 models) or a NexSens UW Sonde Cable Adapter (EXO 3). The EXO DCP adapter converts the proprietary signal from the sonde into either SDI-12 or RS-232 signals. For buoy systems, NexSens recommends the UW to EXO Sonde Cable Adapter, which provides a waterproof enclosure for the DCP adapter, with external connections between the sonde and X2 data logger. For pole mount systems, the DCP adapter can be mounted within a waterproof NexSens A50 junction box, with internal wiring between a NexSens flying lead plug cable, and a YSI EXO flying lead cable or NexSens MCIL6-FS flying lead cable. Follow the link below to properly wire a DCP adapter into an A50 junction box for connection with an X2 data logger.


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 pin numbers.


NexSens UW8 Pin NumberSignal



For additional information on the YSI EXO-Series Sondes, please refer to the YSI EXO User Manual.