Example: Modbus Master visual mapper to KNX group addresses


Starting from firmware from 14.11.2014 there is visual Modbus mapper included in LogicMachine3. It is used for mapping Modbus objects to KNX.

Modbus device profile

First thing you should do is to define Modbus device profile – it is a *.json file with the following structure e.g. a fragment from UIO20 device by Embedded Systems:

“manufacturer”: “Embedded Systems”,
“description”: “Universal 16+4 I/O module”,
“mapping”: [
{ “name”: “Output 1”, “bus_datatype”: “bool”, “type”: “coil”, “address”: 0, “writable”: 1 },
{ “name”: “Input 1”, “bus_datatype”: “float16”, “type”: “inputregister”, “address”: 0, “value_multiplier”: 0.001, “units”: “V” }

You can download full UIO20.json profile file here


When the Modbus device profile file is created, upload it by clicking on Profiles button.


Adding Modbus device

Once profiles are defined and RTU settings set, add Modbus device by clicking Add device button.


Once the device is added, you can do mapping to KNX addresses by clicking on icon. First, you see a list of all objects on the Modbus device.


Click on specific object to do mapping.