RS485 Dual DS18B20 Temperature Module

The N4DSB03 Dual Channel RS485 Temperature Module enables reliable monitoring of two DS18B20 sensors over a Modbus RTU network. With a wide input range and industrial-grade RS485 communication, it is ideal for distributed temperature sensing in automation, HVAC, and environmental systems, offering stable, accurate, and scalable performance across applications.

Quick Spec

• Channel: Dual DS18B20 temperature input
• Communication: RS485 Modbus RTU
• Supply Range: 6–25 V DC
• Current: 7-8mA per Module 
• Default baud rate: 9600 bps
• Supports 1200–115200 bps serial speed
• Modbus read commands: 03 / 04
• Modbus write commands: 06 / 16
• Up to 32 modules per RS485 bus
• Compact PCB: 32.6 × 25.8 mm

Connections

In this circuit, two DS18B20 temperature probes are connected to the N4DSB03 dual-channel RS485 temperature module.

Multiple Modules on Bus

Ensure each N4DSB03 module has a unique RS485 address. If more than 16 modules are connected, consider using an R485 repeater to maintain signal integrity over longer bus lengths.

Why Termination Resistors Are Not Optional

Termination resistors are not just a best practice—they are a requirement for maintaining reliable communication, especially in systems with long cables or high data rates. Here’s why they matter

Resistor Selection

A 120-ohm, ¼-watt metal film resistor is generally sufficient for most industrial environments. While some short-distance setups (less than a few meters) might work without termination, it’s still recommended for high-speed communication to ensure long-term stability.

Software Tools

• QModMaster is a free, open-source software tool used to communicate with Modbus devices over RS485

Resources

• Document by Manauls.plus 
• Github Repository 

Shipping List

• 1 x RS485 Dual DS18B20 Temperature Module