Serial Communication Component

The RuleGo IoT component library provides serial communication support, allowing rule chains to interact with serial devices. It provides four functional components: read, write, request, and control.

Requires extension library: rulego-components-iot (opens new window)

Component List

Component Name	Type	Description
Serial In	x/serialIn	Reads data from a serial port. Supports splitting data by character, timeout, or fixed length.
Serial Out	x/serialOut	Writes data to a serial port. Supports automatically appending trailing characters.
Serial Request	x/serialRequest	Writes data and waits for a response (blocking). Supports timeout and response splitting logic.
Serial Control	x/serialControl	Controls the serial port connection status (open/close).

Common Configuration

All serial components share the following connection configuration:

Field	Description	Example
port	Serial port name, e.g., COM1 (Windows) or /dev/ttyUSB0 (Linux)	COM3
baudRate	Baud rate	9600
dataBits	Data bits	8
stopBits	Stop bits ("1", "1.5", "2")	1
parity	Parity (N: None, O: Odd, E: Even, M: Mark, S: Space)	N
dtr	DTR control (true, false)	true
rts	RTS control (true, false)	false

Note: Multiple nodes with the same port will share the same underlying connection instance.

1. Serial In (x/serialIn)

Used to read data from a serial port. The read operation is triggered when an input message is received (usually used with a timer).

Specific Configuration

Field	Description	Default
startChar	Start character. If set, discards data until this character is matched.	-
splitType	Split type: char (by character), timeout (by timeout), fixed (by length)	timeout
splitKey	Split parameter. Delimiter if split by char (e.g., \n); number of bytes if split by length.	-
splitTimeout	Read segment timeout (ms). If no data for this duration, segment ends.	100
dataType	Output data type: text (UTF-8), binary, hex, base64	text

2. Serial Out (x/serialOut)

Used to write data to a serial port.

Specific Configuration

Field	Description	Default
data	Send content, supports dynamic variable replacement (e.g., ${data}). If empty, msg.Data is used.	-
addChar	Append character. Automatically appended to data when sending (supports \n, \r, etc.).	\r\n
dataType	Input data type: text (default), hex, base64. If not text, the data will be decoded before sending.	text

Input Message

If the data configuration is empty, msg.Data will be used as the content to send.

3. Serial Request (x/serialRequest)

Used for "Request-Response" pattern. Sends data first, then blocks waiting for a response.

Specific Configuration

Includes data, addChar, dataType from Serial Out and all split configurations from Serial In (startChar, splitType, dataType, etc.), plus:

Field	Description	Default
requestTimeout	Total request timeout (ms).	10000

4. Serial Control (x/serialControl)

Used to manually control the serial connection.

Specific Configuration

Field	Description	Default
action	Control instruction, supports dynamic variable replacement (e.g., ${msg.action}). If empty, msg.Data is used as the instruction.	close

Input Message

If the action configuration is empty, msg.Data content is used as the control instruction:

• open: Open the serial connection (normally the component opens it automatically, this is for manual reconnection).
• close: Close the serial connection.
• dtr=1: Set DTR signal to High.
• dtr=0: Set DTR signal to Low.
• rts=1: Set RTS signal to High.
• rts=0: Set RTS signal to Low.
• flush: Clear both input and output buffers.
• flush_in: Clear input buffer.
• flush_out: Clear output buffer.