User Guide
The NexSens T-node FR Thermistor provides high precision temperature measurements. When multiple are assembled into a chain, the T-node FR can be used for temperature profiling in lakes, streams, and coastal waters. It features an integral titanium thermistor secured and epoxied in a protective housing for underwater deployments.
NexSens T-node FR Thermistor
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 pre-assembled string with multiple nodes, the nodes will be addressed in increasing numerical order.
Modbus-RTU Register Information
| Function 0x04 (Read input registers) | |||
| Registers | Data Type | Data Size | Purpose |
| 0x0006,0x0007 | Float | 2 registers | Requests the temperature recorded by a T-node FR sensor in Celsius |
Ex. 01, 04, 00, 06, 00, 02, 91, CA
- Requests the temperature reading of a T-node FR sensor with Modbus address 1, reported in Celsius.
| Function 0x10 (Write multiple registers) | |||
| Registers | Data Type | Data Size | Purpose |
| 0x1000 | Integer | 1 register | Changes the Modbus Address of the T-node FR sensor node |
Ex. FB, 10, 10, 00, 00, 01, 02, 00, 05, 0D, 36
- Changes a T-node FR node (at the universal Mobus address of 251) to a new address of 5.
CAUTION- Only connect a single T-Node FR at one time when sending the address change command, especially when the universal address ‘251’ is used.
UW-FLxR Cable Connection
The NexSens UW-Receptacle to Flying Lead cable is an accessory that may be purchased separately for integration of a T-node FR string with a third-party data logger or SCADA system. NexSens X2-series data loggers have built-in UW-receptacle ports to accomodate a direct connection of the string.
UW-FLxR Wiring Table
| Receptacle Pin | Wire Color | T-Node FR Signal |
| 1 | Green | RS485A |
| 2 | Blue | RS485B |
| 3 | Brown | Pass-through |
| 4 | Red | 12VDC |
| 5 | White | Pass-through |
| 6 | Yellow | Pass-through |
| 7 | Black | GND |
| 8 | Orange | Pass-through |
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.
Connector Inspection
Whenever a string is assembled or re-connected, verify that the plug and receptacle O-rings of each sensor and UW-connector cable are present and in good condition. Additionally, verify that there are no signs of moisture or corrosion on any of the T-Node FR or UW-cable connectors (if re-deploying an old string).
Inspect the plug and receptacle O-rings on each T-Node FR thermistor as well as on all sensor cables comprising the string.
TS-Clamp mooring line connection
The TS-Clamp accessory can be used to affix a T-node FR thermistor string to a mooring line for deployment.
Cable Armoring
For any T-node FR deployment, apply cable armor to all portions of the sensor string that have the potential to wear against irregular surfaces.
Maintenance
There is very little maintenance required for T-Node FR temperature strings because they are designed for long-term deployments in submersible applications.
- Cleaning
- Any bio-fouling that accumulates on T-node FR temperature strings during deployments should be cleaned using a soft cloth or soft-bristled brush along with soap and water.
- Calibration
- T-Node FR thermistors are capable of holding their factory calibration indefinitely and do not require re-calibration.
- Storage
- T-Node FR thermistor strings should be stored in a cool, dry place.