User Guide

The NexSens TS210 Thermistor String provides high precision temperature measurements for profiling in lakes, streams, and coastal waters. It features an integral titanium thermistor secured and epoxied in a protective housing for underwater deployments. A marine-grade cable with braided Kevlar core help ensure reliability in extreme environments. Each sensor is accurate to +/-0.075 C for high-precision measurements. The exposed titanium thermistor makes direct contact with water, allowing readings to stabilize within 60 seconds. Temperature data is transmitted on a RS-485 Modbus RTU string bus for integration with data loggers and SCADA systems. The string is powered by 4-28 VDC for operation on a 12 or 24 VDC power supply. TS210 strings are available standard with 1m spacing or at custom intervals to meet project requirements. Cable lengths are available up to 1,219 meters (4,000 feet) with a maximum 250 nodes. Strings terminate in a NexSens UW plug and receptacle connector, allowing additional sections or sensors to be added as required. Optional accessories include a bottom pressure sensor, cable clamps, stainless steel mooring line, and communication adapters.


NexSens TS210 Thermistor String



  • Sensor: Thermistor
  • Range: 0 to 45 C (32 to 113 F)
  • Accuracy: +/-0.075 C
  • Resolution: 0.01 C
  • T90 Response Time: 60 seconds
  • Refresh Rate: 2 seconds
  • Maximum Sensors: 250
  • Maximum Length: 1219m (4000 ft.)
  • Communications: RS-485 Modbus RTU
  • Power Requirement: 4-28 VDC
  • Current Draw Per Node: 1.3mA active; 0.35mA sleep; 0.05mA deep sleep
  • Connector: 8 pin, sensorBUS
  • Dimensions: 7.62cm L x 3.56cm Dia. (3.0″ L x 1.4″ Dia.

Sensor Information

  • Power Requirement: 5-24VDC
  • Protocol: Modbus-RTU
  • Baud Rate: 19200
  • Parity: N81
  • Default Address: 1*
  • Universal Address: 251
  • Format: Big Endian
  • Timeout: 500ms

*On a string with multiple nodes, the nodes will be addressed in increasing numerical order. Use extreme caution when changing the address of a node in a TS210 string to ensure that the nodes remain in numerical order and the same address is not assigned to more than one node simultaneously.


UW-FLxR Cable Connection

The NexSens UW-Receptacle to Flying Lead cable is an accessory that may be purchased separately for integration of a TS210 string with a third-party data logger or SCADA system. NexSens X2-series data loggers have built-in UW-receptacle ports to accommodate a direct connection of the string.

Receptacle PinWire ColorTS210 Signal


NexSens UW-FLxR pinout.



Modbus-RTU Register Information

Read Input Registers

Function 0x04 (Read input registers)
RegistersData TypeData SizePurpose
0x0006, 0x000732-bit Float, Big-endian2 registersRequests the temperature recorded by a T-node FR sensor in Celsius



Field NameHexField NameHex
Slave Address0x01Slave Address0x01
Start Address Hi0x00Byte count0x04
Start Address Lo0x06Register Value Hi0x41
Quantity of register0x00Register Value Lo0xAF
Quantity of register0x02Register Value Hi0x38
CRC Lo0x91Register Value Lo0x1D
CRC Hi0x50
  • The user has requested a temperature reading from the TS210 sensor with address 1. The sensor responded with 0x41af381d (21.9024°C).



Write Multiple Registers

Function 0x10 (Write Multiple registers)
RegistersData TypeData SizePurpose
0x100016-bit Integer1 registerChanges the Modbus Address of the first node on a TS210 string*

*Assuming the first node of the TS210 string begins with address 1.



Field NameHexField NameHex
Slave Address0x01Slave Address0x01
Start Address Hi0x10Start Address Hi0x10
Start Address Lo0x00Start Address Lo0x00
Quantity of register0x00Quantity of Outputs Hi0x00
Quantity of register0x01Quantity of Outputs Hi0x01
Byte count0x02CRC Lo0x05
Outputs Value Hi0x00CRC Hi0x09
Outputs Value Lo0x05
CRC Lo0x77
CRC Hi0x92
  • Using the known address of 1, the user has changed the Modbus address of the sensor with address 1 to 5.



Universal Address

The TS210 is programmed such that any sensor will respond to Modbus address 251. This is implemented for the event that the sensor’s current address is unknown. This address should only be queried with one sensor connected to the data line. If more than one sensor is connected, both will respond and a bad message is likely.

Note: Universal address should not be used with TS210 sensors that have more than one node. Only use address 251 if there is a single sensor connected.


Read Current Address Using Universal Address

Function 0x04 (Read input registers)
RegistersData TypeData SizePurpose
0x100016-bit integer1 registerUses the univeral address (251) to read the current T-Node address



Field NameHexField NameHex
Slave Address0xFBSlave Address0xFB
Start Address Hi0x10Byte count0x02
Start Address Lo0x00Register Value Hi0x00
Quantity of register0x00Register Value Lo0x07
Quantity of register0x01CRC Lo0x20
CRC Lo0x21CRC Hi0xE6
CRC Hi0x50
  • Using the universal address of 251 (0xFB), the user has read that the current Modbus address of the sensor is 7 (0x0007).


Change the Modbus Address in iChart

A single T-Node FR sensor or T-Node FR/TS210 temperature string can be directly connected to a PC using a NexSens RS-485 UW Sensor USB Adapter. This adapter provides the ability to check sensor functionality or adjust the sensor’s Modbus address. Follow the article below for further information.

Change the Modbus Address of a T-Node FR


Pre-Deployment Check/Setup

It is recommended that field deployments be carefully planned, and it is best to completely configure the system on a lab bench and test it for a period of time prior to taking it to the field. This will ensure a successful deployment and quality data collection. Additionally, it is much easier to troubleshoot problems in the lab than in the field.


TS-Clamp mooring line connection

Temperature strings are frequently attached to a mooring line to keep them fixed in place vertically within a water column. This technique helps to ensure that temperature data is consistently
being monitored at the desired depths. With the temperature string laid out on a flat surface, secure each TS210 to the sensor mooring line using TS-Clamp sensor mooring clamps. The TS-Clamp accessory can be used to affix a TS210 thermistor string to a mooring line for deployment.


Cable Armoring

For any TS210 deployment, apply cable armor to all portions of the sensor string that have the potential to wear against irregular surfaces.



There is very little maintenance required for TS210 temperature strings because they are designed for long-term deployments in submersible applications.

  • Cleaning
    • Any bio-fouling that accumulates on TS210 temperature strings during deployments should be cleaned using a soft cloth or soft-bristled brush along with soap and water.
  • Calibration
    • TS210 thermistors are capable of holding their factory calibration indefinitely and do not require re-calibration.
  • Storage
    • TS210 thermistor strings should be stored in a cool, dry place.