Modbus Line Set Coil
ModbusLineSetCoilAction writes one coil value on one slave device managed by a ModbusLineThing. Use it for precise relay, output, or command-bit control on a shared RS485 bus or Modbus TCP gateway.
Write one coil on a selected slave device
Unlike ModbusSetCoilsAction, this action targets a specific slave ID and one coil address through ModbusLineThing. The device must be present, enabled, online, and configured with the target coil in its map.
Slave specific
Targets one slave on a shared Modbus line.
Single output
Writes exactly one coil to true or false.
Automation ready
Useful for rules such as Open gate, Enable pump, or Reset relay.
Multi-device relay control
Shared bus relay board
Use when the output belongs to one slave on a line, for example slave 7, coil 3.
Clear action names
Create separate actions such as Open gate, Close gate, Enable pump, and Disable pump.
Rule-driven control
Attach to Event Manager when one detected condition should set one coil on one slave.
Configuration parameters
| Parameter | Required | Description | Default |
|---|---|---|---|
Title | Yes | Display name of the action. | None |
Modbus line | Yes | Target ModbusLineThing. | None |
Device | Yes | Slave device ID inside the selected line. | None |
Address | Yes | Raw Modbus coil address to write. | None |
On / Off | Yes | Value written to the selected coil. | false |
Operational notes
Device must be online
The selected slave must be present and online. Disabled devices are skipped by line actions.
Map must include the coil
If the UI does not offer the coil, run discovery or manually add it to the device map.
Confirmation depends on readability
If the coil is readable, the next poll confirms the value. Write-only outputs may show local feedback only.