ModSlaveSim is a programmable simulator that enables realistic simulation of a Modbus slave in its environment. So Modbus masters can be connected to ModSlaveSim, instead of a real Modbus slave device, in order to test and configure the masters.

Using a simple control language you can simulate a Modbus slave measuring environment properties (e.g. flow rate), controlling the environment (e.g. opening valves), performing internal calculations (e.g. averages), and responding to Modbus commands from masters.

ModSlaveSim displays the Modbus device registers as they change, and provides a trace of Modbus messages between slaves and masters. It also has a troubleshooting facility.

The aim of the First Steps section is to provide an insight into ModSlaveSim as a simulator of Modbus devices, and to enable some basic settings to be quickly configured.

In this manual the traditional Modbus terms "master" and "slave" are used. If you are from a networking background, you might find the manual easier to read if you substitute "client" for "master" and "server" for "slave".