Creating a New Modbus Device Profile

If your Modbus device profile is not included in the preinstalled profiles in the controller, you can define your own custom profile.

Follow these steps:

1. File format: Modbus device profiles are distributed as *.json files. You can create and edit these files using a common text editor (such as Notepad or Notepad++). Remember to save the file with the extension *.json.

2. Profile structure example:

   {
      "manufacturer": "Schneider Electric",
      "description": "Example device",
      "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"
        }
      ] 
   }

   • The "mapping" table in the *.json file contains information for each Modbus register, coil, input, or output.

   • Adjust the mapping settings according to your specific device:

     Parameter	Description	Type	Required
     Name	Object name, e.g. Output 2	String	Yes
     bus_datatype	KNX object data type, key from dt table, e.g. float32	String/Number	Yes
     type	Modbus register type, possible values: coil, discreteinput, register, inputregister.	String	Yes
     address	Register address (0-based)	Number	Yes
     writable	Set to true to enable writing to register if type is either coil or register.	Boolean	No
     write_only	Set to true to disable reading coil or register value when "writable" is enabled.	Boolean	No
     datatype	Modbus value data type. If set, conversion will be done automatically. Possible values: bool,  uint16, int16, float16, uint32, int32, float32, uint64, int64, quad10k, s10k	String	No
     value_delta	New value is sent when the difference between previously sent value and current value is larger than delta. Defaults to 0 (send after each read).	Number	No
     value_base	Add specified number to the resulting value.	Number	No
     value_multiplier	Multiply resulting value by the specified number,value = value_base + value * value_multiplier.	Number	No
     value_bitmask	Bit mask to apply, shifting is done automatically based on least significant 1 found in the mask.	Number	No
     value_nan	Array of 16-bit integers. If specified and read operation returns the same array no further processing of value is done.	Array	No
     value_conv	Apply one of built-in conversion functions	String (Int)	No
     value_custom	Name of a built-in enumeration or a list of key -> value mapping, resulting value will be 0 if key is not found.	String/Object	No
     internal	Not visible to user when set to true, should be used for scale registers.	Boolean	No
     units	KNX object units/suffix	String	No
     address_scale	Address of register containing value scale, value = value * 10 ^ scale	Number	No
     read_count	Number of register to read at once (for devices that only support reading of a specific block of registers)	Number	No
     read_swap	Swap register order during conversion (endianness)	Boolean	No
     read_offset	Position of first register of data from the block of registers (0-based).	Number	No
     timeout	Specify device timeout in seconds. If the extension device does not reply within specified time, it is considered as timeout error. Default values: 0.5 s for Modbus RTU, 3 s for Modbus TCP	Number	No
     write_multiple	This parameter set the multiple writing function (function 15 or 16 is used instead of function 5 or 6). If "Type" is set to "register" and "Write_multiple" is set to "true", Modbus function 16 is used for writing to the register. If "Type" is set to "coil" and "Write_multiple" is set to "true", Modbus function 15 is used for writing to the coil. Default value is "false", which means that Modbus function 5 or 6 (depending on register type) is used for writing.	String	No

3. Upload to the controller:

   • Once you have created your *.json file with all the necessary profile information, upload it to the controller via Configurator → Modbus → Profiles → Add profile.

4. Best practice:

   • When creating a new device profile, consider using an existing profile as an example or template. You can download existing profiles from the controller to understand the structure and syntax.

For detailed instructions on custom device profile creation, refer to the application note available at Schneider Electric website.