Design Your Register Map

Set up a virtual slave's register values like a real device would.

When you build a Modbus slave device — a sensor, a controller, a gateway — you define its register map: which address holds which value.

Good register maps are documented and logical: group related values together, add padding for future expansion, and document the units and scaling (e.g. HR 5 = temperature × 10 in °C).

The virtual slave below is yours to configure. It represents a weather station with these registers: • HR 0 = Temperature (°C × 10) • HR 1 = Humidity (%RH × 10) • HR 2 = Pressure (hPa) • HR 3 = Wind speed (km/h × 10) • Coil 0 = Rain sensor (ON = raining)

Set realistic values — a hot summer day: 32.5°C, 65.0% humidity, 1013 hPa, 12.0 km/h wind, no rain.