Modbus

The Modbus component provides Modbus-TCP communication protocol on tcp port 502 for supported Shelly devices.

The Modbus component uses Modbus as RPC namespace and implements the following methods:

• Modbus.GetConfig to obtain the component's configuration
• Modbus.SetConfig to update the component's configuration
• Modbus.GetStatus to obtain the component's status

Methods

Modbus.SetConfig

Properties:

Property	Type	Description
config	object	Configuration that the method takes

Find more about the config properties in config section

Modbus.GetConfig

Find the Modbus.GetConfig response properties in config section

Modbus.GetStatus

Find more about the status response properties in status section

Configuration

The configuration of the Modbus component enables or disables the server.

Properties:

Property	Type	Description
enable	boolean	Set true to enable.

Status

The status of the Modbus component shows whether the server is successfully enabled.

Property	Type	Description
enabled	boolean	true if enabled, false if disabled.

Registers

Every Shelly component that supports Modbus has its own set of registers, listed in its documentation:

• EM
• EMData

Device info registers:

Address	Type	Description
30000	ASCII string	Device MAC (6 registers / 12 bytes)
30006	ASCII string	Device model (10 registers / 20 bytes zero padded)
30016	ASCII string	Device name (32 registers / 64 bytes zero padded)

Modbus.SetConfig example

Modbus.SetConfig HTTP GET Request

http://192.168.33.1/rpc/Modbus.SetConfig?config={"enable":true}

Modbus.SetConfig Curl Request

curl -X POST -d '{"id":1,"method":"Modbus.SetConfig","params":{"config":{"enable":true}}}' http://${SHELLY}/rpc

Modbus.SetConfig Mos Request

mos --port ${PORT} call Modbus.SetConfig '{"config":{"enable":true}}'

Response

Modbus.SetConfig HTTP GET Response

{
  "restart_required": false
}

Modbus.SetConfig Curl Response

{
  "id": 1,
  "params": {
    "restart_required": false
  }
}

Modbus.SetConfig Mos Response

{
  "restart_required": false
}

Modbus.GetConfig example

Modbus.GetConfig HTTP GET Request

http://192.168.33.1/rpc/Modbus.GetConfig?

Modbus.GetConfig Curl Request

curl -X POST -d '{"id":1,"method":"Modbus.GetConfig","params":{}}' http://${SHELLY}/rpc

Modbus.GetConfig Mos Request

mos --port ${PORT} call Modbus.GetConfig '{}'

Response

Modbus.GetConfig HTTP GET Response

{
  "enable": true
}

Modbus.GetConfig Curl Response

{
  "id": 1,
  "params": {
    "enable": true
  }
}

Modbus.GetConfig Mos Response

{
  "enable": true
}

Modbus.GetStatus example

Modbus.GetStatus HTTP GET Request

http://192.168.33.1/rpc/Modbus.GetStatus?

Modbus.GetStatus Curl Request

curl -X POST -d '{"id":1,"method":"Modbus.GetStatus","params":{}}' http://${SHELLY}/rpc

Modbus.GetStatus Mos Request

mos --port ${PORT} call Modbus.GetStatus '{}'

Response

Modbus.GetStatus HTTP GET Response

{}

Modbus.GetStatus Curl Response

{
  "id": 1,
  "params": {}
}

Modbus.GetStatus Mos Response

{}

Useful Tools

Many tools can be used to send MODBUS TCP requests to and receive responses from Shelly devices. Some of them are:

modbus_cli

This Python modbus client, as stated in it's documentation can Read and write registers of Modbus devices. GitHub link

Example 1:

Reading timestamp of last update of EM component

modbus -B mixed 192.168.2.48 i@1000/I
Parsed 0 registers definitions from 1 files
1000: 1669379021 0x6380b3cd

Example 2:

Reading voltage on Phase A

modbus -B mixed 192.168.2.48 i@1020/f
Parsed 0 registers definitions from 1 files
1020: 232.2854461669922