Server Overview
Server mode turns Modbux into a virtual Modbus device. You simulate a server (slave) that a client can connect to, without needing any physical hardware.
When do you use Server mode?
- You're developing software that needs to communicate with a Modbus device, but the device isn't available yet
- You want to test your client configuration before working with a real device
- You want to set up a demo environment
- You want to develop both sides of a communication simultaneously with Split mode
Features
Multiple Unit IDs
A single server can simulate up to 248 virtual devices (Unit ID 0-247), each with their own registers. For example, simulate a temperature sensor on ID 1 and a pressure sensor on ID 2.
Multiple servers
Run up to 10 independent servers simultaneously, each on its own port. Useful when you need to test multiple network segments or protocol variants.
Value generators
Let register values randomize automatically between a min and max at a set interval. Useful for verifying that your client's polling works and handles changing data correctly.
Interface at a glance
At the top you manage your servers: add or remove servers, give them a name, choose the port and select which Unit ID you want to configure.
Below that are four collapsible panels, one per register type (Coils, Discrete Inputs, Input Registers, Holding Registers). This is where you add registers and set values.
Servers start automatically as soon as you create them. There's no start/stop button. Your server is immediately reachable.
See Server Configuration for a step-by-step guide on configuring registers and value generators.