How to Use ModbusTool for Master/Slave Simulation

ModbusTool is an open-source, cross-platform utility developed by ClassicDIY that functions as both a Modbus Master (Client) and Modbus Slave (Server). It is widely used by engineers and developers to test, debug, and simulate industrial network communications without requiring physical hardware. Prerequisites for Simulation

To run a full Master/Slave simulation on a single computer, you need to establish a bridge for the two sides to talk to each other:

For Modbus TCP: No extra software is required. Both instances can communicate locally using the IP address 127.0.0.1 (localhost).

For Modbus RTU (Serial): You must install a Virtual Serial Port Driver (such as VSPD or com0com) to create a linked pair of virtual COM ports (e.g., COM1 and COM2). The Master will connect to one port, and the Slave will connect to the other. Step 1: Setting Up the Modbus Slave (Server)

The Slave holds the data registers that the Master will read from or write to. Modbus Poll