Modbus Actions

Action Types

Action	actionType	Description
ACTION_MODBUS_COIL_WRITE	16	Write coil (FC05)
ACTION_MODBUS_REG_WRITE	17	Write register (FC06)
ACTION_MODBUS_POLL	18	Poll collection

Configuration Examples

Method 1: Web Interface Configuration (Recommended)

The peripheral execution page and Modbus RTU configuration page are shown below. When configuring Modbus actions, verify serial port parameters, slave address, function code, register or coil address.

Area	Field	Example Value / Status
Status Overview	Risk Level	Low
Status Overview	Enabled Tasks	0
Status Overview	Timeout Rate	0%
Status Overview	Total Polls / Success / Failed / Timeout	0 / 0 / 0 / 0
Basic Config	Enable Modbus RTU	Enabled
Basic Config	Peripheral Config Selection	Select configured RS485/UART peripheral
Basic Config	Transfer Type	Passthrough (Raw HEX frames)
Basic Config	DE Pin (RS485)	14

Sub-device Name	Type	Slave Address	Device Info	Enable	Actions
Temp/Humidity	Collection	2	FC04 @0 x2 [2 mappings]	ON	Edit / Map / Delete
PM25-10	Collection	1	FC03 @0 x2 [2 mappings]	ON	Edit / Map / Delete
Weather Louver	Collection	4	FC03 @500 x8 [6 mappings]	ON	Edit / Map / Delete

Example 1: Write Coil (Control Relay On/Off)

Scenario: Turn on channel 0 (channel 0) of Modbus relay

Configuration Steps:

1. Edit the rule in the Peripheral Execution Management page

2. Click the Add Action button

3. Fill in the action configuration:

   Field	Value	Description
   Action Type	Select Modbus Write Coil	FC05
   Target Peripheral	Select mb_relay	Modbus relay
   Channel Number	0	Based on coilBase offset
   Value	1	1=ON, 0=OFF

4. Click the Save button

💡 Tip: Channel number is based on the coilBase offset in peripheral configuration; check device manual to confirm

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Example 2: Write Register (Set PWM Value)

Scenario: Write register value 512 to Modbus PWM module

Configuration Steps:

1. Edit the rule, add an action

2. Fill in:

   • Action Type: Select Modbus Write Register
   • Target Peripheral: Select mb_pwm
   • Register Address: 100
   • Write Value: 512

3. Click Save

💡 Tip: Check device manual to confirm register address

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Example 3: Poll Collection (Read Sensor Data)

Scenario: Poll Modbus task 0 for sensor data

Configuration Steps:

1. Edit the rule, add an action

2. Fill in:

   • Action Type: Select Modbus Poll
   • Target Peripheral: Enter modbus-task:0 (fixed format)
   • Task Index: [0] (JSON array format)
   • Report Data: ✅ Enable the rule's report data option

3. Click Save

💡 Tip:

• targetPeriphId format is fixed as modbus-task:N, N is device index
• actionValue format: {"poll":[0,1,2]}, array contains task indices
• When "Report Data" is enabled, collection results are automatically reported via MQTT

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Example 4: Multi-device Polling

Scenario: Poll multiple tasks (0, 1, 2) at once

Configuration Steps:

1. Edit the rule, add an action

2. Fill in:

   • Action Type: Select Modbus Poll
   • Target Peripheral: Enter modbus-task:0
   • Task Index: [0,1,2]

3. Click Save

💡 Tip: Multiple task indices separated by commas; system polls in order

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Method 2: JSON Configuration File Import

Complete Rule Example

Platform Control Modbus Relay

{
  "id": "exec_mb_ctrl",
  "name": "Remote Control Relay",
  "enabled": false,
  "execMode": 0,
  "triggers": [
    {
      "triggerType": 0,
      "triggerPeriphId": "mb_relay_ch0",
      "operatorType": 0,
      "compareValue": "1",
      "timerMode": 0,
      "intervalSec": 60,
      "timePoint": "",
      "eventId": "",
      "pollResponseTimeout": 1000,
      "pollMaxRetries": 2,
      "pollInterPollDelay": 100
    }
  ],
  "actions": [
    {
      "targetPeriphId": "mb_relay",
      "actionType": 16,
      "actionValue": "{\"ch\":0,\"val\":1}",
      "useReceivedValue": false,
      "syncDelayMs": 0,
      "execMode": 0
    }
  ],
  "protocolType": 0,
  "scriptContent": "",
  "reportAfterExec": true
}

Precautions

1. Modbus Availability: Action execution checks if Modbus channel is ready
2. Communication Interval: Recommended syncDelayMs ≥ 100ms between multiple Modbus actions
3. Timeout Handling: Modbus communication timeout records failure and triggers backoff mechanism
4. Data Reporting: MODBUS_POLL results are automatically reported via MQTT when reportAfterExec: true