This version of the DS18B20 waterproof temperature probe is supplied with a pluggable screw-terminal adapter and 3-pin connection cable. The adapter makes the normal three-wire DS18B20 connection easier and includes the required 1-Wire pull-up resistor.

This guide covers the probe wire colours, adapter pinout, Arduino UNO wiring, library installation, basic temperature-reading code, resolution and common troubleshooting.

Overview Adapter Pinout Arduino Wiring Libraries Arduino Test Resolution Troubleshooting

DS18B20 Probe & Adapter Overview

Sensor DS18B20

Interface 1-Wire Digital

Supply Voltage 3.0–5.5V DC

Cable Length 1 metre

Resolution 9–12 bit

Specified Accuracy ±0.5°C from -10 to +85°C

The DS18B20 is a digital temperature sensor that communicates over a 1-Wire data connection. Unlike an analogue temperature sensor, the controller receives a digital temperature value rather than measuring an analogue voltage.

The required pull-up resistor is already fitted.

The terminal adapter includes a 4.7kΩ pull-up resistor between the 1-Wire data line and VCC. When using the supplied adapter in the standard three-wire configuration, no separate 4.7kΩ resistor needs to be added.

The sensor IC and cable do not have the same temperature limit.

The DS18B20 sensor itself supports measurements from -55 to +125°C, but the cable supplied with this probe is specified for a maximum temperature of 85°C. Keep the cable and cable entry within their rated temperature even when the stainless steel probe tip is measuring a hotter location.

Keep the adapter electronics dry.

The stainless steel probe is supplied as a waterproof temperature probe, but the screw-terminal adapter, jumper connections and controller are not waterproof. Keep these electrical parts dry. No specific IP, pressure or maximum immersion-depth rating is specified for the complete assembly.

Terminal Adapter Pinout

The adapter provides three labelled connections: DAT, VCC and GND. The same functions are marked beside the 3-pin output header.

Adapter Label	Function	Connects To
DAT	1-Wire data signal	Controller digital GPIO
VCC	Sensor power and pull-up supply	3.3V or 5V supply as appropriate
GND	Ground	Controller GND

Connecting the Probe to the Screw Terminals

The DS18B20 probe supplied with this product uses the following wire colours:

Probe Wire	Adapter Terminal	Function
Yellow	DAT	1-Wire data
Red	VCC	Sensor power
Black	GND	Ground

Probe wiring

Connect the yellow wire to DAT, the red wire to VCC and the black wire to GND. Insert the stripped conductor fully into the screw terminal and tighten each terminal securely before applying power.

3-Pin Output Header

The controller-side header is also labelled DAT, VCC and GND on the adapter PCB. Follow these printed labels when connecting the supplied 3-pin cable.

Do not identify the output pins only by jumper-wire colour.

Jumper cable colours are not an electrical standard. Confirm which conductor is connected to DAT, VCC and GND at the adapter before connecting the other end to your controller.

Arduino UNO Wiring

The example below uses Arduino digital pin D2 for the DS18B20 data connection.

Adapter	Arduino UNO	Function
DAT	D2	1-Wire data
VCC	5V	Sensor power and pull-up supply
GND	GND	Common ground

No separate pull-up resistor is required.

The 4.7kΩ pull-up resistor required by the DS18B20 1-Wire data line is already present on this adapter.

Using a 3.3V controller

When connecting the adapter to an ESP32, Raspberry Pi or another controller with 3.3V-only GPIO, power the adapter from an appropriate 3.3V supply. The adapter's pull-up resistor connects DAT towards VCC, so powering the adapter from 5V would also pull the data line towards 5V.

Arduino Library Installation

The Arduino example uses the DallasTemperature library together with the OneWire library.

Open the Arduino IDE.
Open Tools > Manage Libraries.
Search for DallasTemperature and install the DallasTemperature library.
Search for OneWire and install the OneWire library by Paul Stoffregen if it is not already installed.
Select your Arduino UNO and the correct serial port.

Arduino UNO Basic Temperature Test

Before uploading the sketch, connect DAT to D2, VCC to 5V and GND to GND.

Arduino UNO – DS18B20 Temperature Test

#include <OneWire.h>
#include <DallasTemperature.h>

const uint8_t ONE_WIRE_BUS = 2;

OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

void setup() {
  Serial.begin(9600);

  sensors.begin();

  Serial.print("DS18B20 sensors found: ");
  Serial.println(sensors.getDeviceCount());
}

void loop() {
  sensors.requestTemperatures();

  float temperatureC = sensors.getTempCByIndex(0);

  if (temperatureC == DEVICE_DISCONNECTED_C) {
    Serial.println("Sensor read failed - check wiring.");
  } else {
    Serial.print("Temperature: ");
    Serial.print(temperatureC, 2);
    Serial.println(" C");
  }

  delay(1000);
}

Expected Result

Open the Arduino Serial Monitor and set it to 9600 baud. The startup message should report one detected sensor when a single probe is connected:

Example Serial Output

DS18B20 sensors found: 1
Temperature: 23.44 C
Temperature: 23.50 C
Temperature: 23.56 C

Your actual temperature will depend on the environment. Hold the stainless steel probe in your hand or place the probe into water at a different temperature. The displayed value should gradually move towards the new temperature.

Temperature Resolution

The DS18B20 supports 9-bit, 10-bit, 11-bit and 12-bit temperature resolution. Higher resolution provides smaller temperature increments but requires more time to complete each measurement.

Resolution	Temperature Step	Maximum Conversion Time
9 bit	0.5°C	93.75ms
10 bit	0.25°C	187.5ms
11 bit	0.125°C	375ms
12 bit	0.0625°C	750ms

Resolution is not the same as accuracy.

At 12-bit resolution the reported value changes in steps as small as 0.0625°C, but this does not mean the sensor is accurate to 0.0625°C. The DS18B20 is specified to ±0.5°C accuracy from -10 to +85°C.

Practical Measurement Notes

Allow the probe temperature to settle

The stainless steel sheath and waterproof probe construction have thermal mass. After moving the probe between air, water or another material, allow enough time for the reading to stabilise before treating it as the final temperature.

Measure with the stainless steel probe section

Position the stainless steel probe where the temperature needs to be measured. Good thermal contact generally produces a more representative reading than leaving the probe loosely exposed near the target material.

Calibration

If your application requires a correction offset, compare the probe with a suitable trusted reference at temperatures relevant to the application. Do not assume a single offset will necessarily remain correct over the complete measurement range.

Multiple DS18B20 probes

DS18B20 sensors have individual device addresses and can share a 1-Wire bus. For a permanent multi-probe installation, identify each sensor by its address rather than relying only on its position in a detected-device list.

Troubleshooting

Arduino reports 0 sensors

Confirm the yellow probe wire is connected to DAT, red to VCC and black to GND.
Confirm DAT on the adapter is connected to Arduino D2 when using the example sketch.
Confirm VCC is connected to Arduino 5V and GND is connected to Arduino GND.
Check that all three screw terminals are tightened securely.
Confirm the supplied 3-pin cable follows the DAT, VCC and GND markings on the adapter.
Confirm both the DallasTemperature and OneWire libraries are installed.

Reading is -127°C or the sketch reports a disconnected sensor

-127°C is used by the DallasTemperature library as a disconnected-device error value.
Check the DAT connection between the adapter and Arduino.
Check the yellow probe wire is firmly connected to the DAT screw terminal.
Check VCC and GND connections at both the probe and controller sides of the adapter.
Disconnect power before correcting any wiring.

Reading repeatedly shows exactly 85°C

+85°C is the DS18B20 temperature register's power-on reset value.
A persistent 85°C reading can indicate that a new temperature conversion is not completing correctly.
Check sensor power, ground and DAT wiring before changing the software.

Readings are intermittent

Tighten the screw terminals so the probe conductors cannot move.
Confirm the 3-pin jumper connectors are fully seated.
Keep the DAT wiring away from motors, relays and other electrically noisy wiring where practical.
Confirm the controller and adapter have a reliable common ground.
Longer or more complex 1-Wire networks may require additional attention to cable layout and bus design.

Temperature changes slowly

This can be normal for a stainless steel waterproof probe because the sheath adds thermal mass.
Ensure the metal probe is in good thermal contact with the material being measured.
Allow time for the probe to stabilise after moving it between different temperatures.

Works on Arduino UNO but not on a 3.3V controller

Check that DAT is connected to the GPIO pin used by your program.
Power the adapter from the controller's appropriate 3.3V supply so the pull-up also operates at 3.3V.
Confirm the controller and adapter share a common ground.
Do not assume Arduino UNO pin numbers or software setup apply unchanged to a different controller platform.

⚠️ Important

Connect the probe with yellow to DAT, red to VCC and black to GND before applying power. The DS18B20 operates from 3.0V to 5.5V, and this terminal adapter already includes the required 1-Wire pull-up resistor. Keep the adapter, jumper connections and controller dry. The DS18B20 sensor IC supports temperatures beyond the rating of the supplied cable, which is specified for a maximum temperature of 85°C.

Still need help?Contact AuscomTech Support and include the product or model shown above.

Contact Support →

CALL US NOW

DS18B20 Waterproof Temperature Sensor Probe with Terminal Adapter – Arduino Wiring, Code & Troubleshooting