Reference
Last revision 2026/01/21
Communication Protocol Description
The sensor uses the RS485 interface that follows the standard Modbus-RTU communication protocol. The serial port parameters (baud rate, parity, stop bits) and other configurations can be managed via the following registers:
| Register Address | Number | Name | Read/Write | Data Range | Default Value | Data Description |
|---|---|---|---|---|---|---|
| 0x00 | 1 | Module PID Register | R | 0x0000-0xFFFF | 0x0002 | Product check (Detect module type) |
| 0x01 | 1 | Module VID Register | R | 0x0000-0xFFFF | 0x0010 | Version check (0x0010 represents V0.0.1.0) |
| 0x02 | 1 | Module Address Register | R/W | 0x0001-0x00F7 | 0x000C | When the sensor address is unknown, write to the register through the broadcast address 0x00, at this time, the sensor will not have data output Save when powered off, take effect after restarting |
| 0x03 | 1 | Serial parameter control register 1 | R/W | 0x0000-0xFFFF | 0x0005 | Module Baudrate: 0x0001---2400 0x0003---9600 0x0004---14400 0x0005---19200 0x0006---38400 0x0007---57600 0x0008---115200 Other----115200 Save when powered off, take effect after restarting |
| 0x04 | 1 | Serial parameter control register 2 | R/W | 0x0000-0xFFFF | 0x0001 | Module check bit H: Stop bit L: 0x00---None 0x00---0.5byte 0x01---Even 0x01---1byte 0x02---Odd 0x02---1.5byte other---none 0x03---2byte Other---1byte Save when powered off, take effect after restarting |
| 0x05 | 1 | Distance register | R | 0x0000-0xFFFF | 0xFFFF | The distance value LSB measured by the module represents 0.1mm |
| 0x06 | 1 | Onboard temperature data register | R | 0x0000-0xFFFF | 0x0000 | The temperature value LSB measured by the onboard temperature sensor represents 0.1℃ （with unit symbol） |
| 0x07 | 1 | External temperature compensation data register | R/W | 0x0000-0xFFFF | 0x0000 | Write ambient temperature data to this register for external temperature compensation, LSB represents 0.1℃ (with unit symbol) |
| 0x08 | 1 | Control register | R/W | 0x0000-0xFFFF | 0x0004 | bit0: 0-use onboard temperature compensation function 1-use external temperature compensation function(Users need to write temperature data to external temperature compensation data register) bit1: 0-enable temperature compensation function 1-disable temperature compensation function bit2: 0-auto detection 1-passive detection bit3: In passive detection mode, write 1 to this bit, then it will measure distance once. The distance value can be read from distance register about 30ms later. This bit is reserved in passive detection mode. This bit will be auto cleared when set to 1 Save when powered off, take effect after restarting |
| 0x09 | 1 | Electrical noise level register | R | 0x0000-0x0A | 0x0000 | 0x0000-0x000A corresponds to noise level 0 to 10. This parameter can show the effect of power supply and environment on the sensor. The smaller the noise level, the more accurate the distance value detected by the sensor. |
Principle
The URM14 ultrasonic ranging sensor operates at a high frequency of 200KHz, using a stable ultrasonic transducer to achieve an effective measuring range of 100mm to 1500mm for flat reflecting walls. It features a 1mm distance resolution and ±0.1% error. The sensor supports flexible temperature compensation (built-in or external) to adapt to complex environments. A built-in noise level evaluation function enables adaptive ranging, with lower noise levels ensuring higher measurement accuracy.
Detection Angle and Sensitivity
Normally, the detection area of an ultrasonic sensor is irregular and hard to define due to its physical characteristics, so the detection angle is indeterminate. In actual use, the detection area and sensitivity of this sensor prove to be smaller than those of other ultrasonic sensors. We used 2 different target obstacles to repeatedly test multiple sample products, and the reference detection area of the corresponding target is as follows:
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