Pin Definition
| Label | Wire | Name | Function Description |
| 1 | Red | + | Power supply positive (5Vdc) |
| 2 | White | TX | Serial port transmit (TXD) |
| 3 | Green | RX | Serial port receive (RXD) |
| 4 | Black | - | Power supply negative（GND） |
Serial Port Parameters
Communication Interface:TTL
Baud Rate:115200bps (fixed)
Data Bits:8
Stop Bits:1
Parity Bit: None
Connection between Sensor and External Controller
| External Controller | M14 Depth Sensor |
| 5V | 5V |
| RXD | TXD |
| TXD | RXD |
| GND | GND |
Parameter Configuration Command Table
| Serial Command | Description | Default Value | Notes |
| !Fxxxx\r\n | Set the sensor to calculate with a specific density value | 997 | "xxxx" represents the set liquid density |
| !Dxx.xx\r\n | Reserved command for depth output offset adjustment | 0 | "xx.xx" is a floating-point offset |
| !Txx.xx\r\n | Reserved command for temperature output offset adjustment | 0 | "xx.xx" is a floating-point offset |
| !!\r\n | Pause sensor output, serial port outputs all parameters | None | |
| !R\r\n | Reset the calculation board | None | |
| !r\r\n | Restore all initial settings | None | |
| !C\r\n | Clear all offset settings | None |
After parameter configuration, the sensor saves the current settings, which remain valid after power-on.
Quick Start：
1.Connect the sensor to the controller and power it on. Confirm the correctness of the power supply and TX/RX connections.
2.After powering on, if there are no connection issues, the sensor will output calculated temperature and depth information.
Data Output Format
Sensor outputs a string in the format: T=XX.XXD=XX.XX\r\n
T represents temperature output in degrees Celsius (°C).
D represents depth output in meters (m).
\r\n indicates the end of each data set.
Example: T=25.27D=1.21 indicates a temperature of 25.27°C and a depth of 1.21m.
Parameter Configuration Commands
!Fxxxx\r\n
xxxx: Liquid density value to be set.
Function: Sets the density of the measured water. Unit: kg/m³.
Freshwater : 997 kg/m³; Saltwater: 1029 kg/m³.
Sensor default: 997 kg/m³.
!Dxx.xx\r\n
xx.xx: Floating-point offset value.
Function: Depth output offset adjustment (for calibration). Adds the offset to the current depth output.
Examples:
Current depth: -0.55, Offset: 0.55 → Output: -0.55 + 0.55 = 0.00
Current depth: 0.10, Offset: -0.10 → Output: 0.10 + (-0.10) = 0.00
!Txx.xx\r\n
xx.xx Floating-point offset value.
Function: Temperature output offset adjustment. Adds the offset to the current temperature output.
Examples:
Current temperature: 25.00°C, Offset: 1.00 → Output: 25.00 + 1.00 = 26.00°C
Current temperature: 25.00°C, Offset: -1.00 → Output: 25.00 + (-1.00) = 24.00°C
!!\r\n
Function: Pauses sensor output and returns all parameters via serial. Send again to resume sensor output.
The format of the serial port output parameters is as follows
FluidDensity:997
Doffset:0.00
Toffset:0.00
!R\r\n
Function: Resets the calculation board.
!r\r\n
Function: Restores all factory default settings.
!C\r\n
Function: Clears all offset settings.
All settings are saved after configuration and remain persistent after power cycling.
Depth Zeroing and Calibration for Sensors
The sensor captures depth and temperature information with the highest sampling accuracy. After power-on reset, the depth value measured in air can be recorded as an offset and added to depth measurements taken underwater. This process calibrates the air-measured depth value as the zero point for depth output.
The temperature output has no built-in calibration. However, it can be calibrated using the temperature offset adjustment command (!Txx.xx\r\n) by referencing measurements from an external temperature sensor.