Model Name: modbus_server

Purpose: This model enables service provision via the MODBUS protocol, allowing remote clients (masters) to acces data.

Instantiation

A model instance is created using modbus_server.

Example:

<window v-model="modbus_server" name="main_view">

Configuration file location: design/default/data/modbus.json

Configuration File Structure

The configuration uses a JSON format.

Basic Settings

• url: Defines the connection endpoint for the slave device.
• unit_id: Identifier for the slave device (not required for TCP).

Example entry:

"url": "tcp://localhost:502"

Channel Definitions

Multiple channels can be defined within the channels array.

Each channel supports specific MODBUS function codes based on its type:

• bits: Accessible with function code 1 (read) and 15 (write).
• input_bits: Read-only using function code 2.
• registers: Read with function code 3; write with function code 16.
• input_registers: Read-only with function code 4.

Parameters include:

• name: Identifier used in UI bindings.
• start: Starting address of the register block.
• length: Number of registers/bits.

Sample definition:

"channels": [
  {
    "name": "bits",
    "writable": true,
    "start": 0,
    "length": 100
  },
  {
    "name": "input_bits",
    "start": 0,
    "length": 200
  },
  {
    "name": "registers",
    "writable": true,
    "start": 0,
    "length": 300
  },
  {
    "name": "input_registers",
    "start": 0,
    "length": 400
  }
]

Variable Mapping

To enhance usability, variables can map to specific addresses with in channels.

Variable declaration example:

"variables": {
  "temperature_current": "input_registers.word[0]",
  "humidity_current": "input_registers.word[1]",
  "temperature_target": "registers.word[0]",
  "humidity_target": "registers.word[1]"
}

Usage in UI components:

<label text="Connection Endpoint" />
<label v-data:value="{url}" />
<label text="Device Identifier" />
<label v-data:value="{unit_id}" />
<label text="Current Temperature" />
<edit input_type="int" v-data:text="{temperature_current}" />
<label text="Current Humidity" />
<edit input_type="int" v-data:text="{humidity_current}" />

<label text="Target Temperature (modified by client)" />
<label v-data:text="{temperature_target}" />
<label text="Target Humidity (modified by client)" />
<label v-data:text="{humidity_target}" />

Data Access

Refer to documentation on modbus_client for accessing channel data.

Predefined Properties

Property	Type	Description
url	string	Connection URI
unit_id	int	Device identifier

Example usage:

<label text="Endpoint" />
<label v-data:value="{url}" />
<label text="ID" />
<label v-data:value="{unit_id}" />

Available Commands

None available.

Reference Implementation

See demo project: demo_modbus_server_registers