node-red-nodes/io/serialport/README.md

node-red-node-serialport
========================

<a href="http://nodered.org" target="noderedinfo">Node-RED</a> nodes to talk to
hardware serial ports.

## Install

To install the stable version use the `Menu - Manage palette` option and search for node-red-node-serialport, or run the following command in your Node-RED user directory, typically `~/.node-red`

        npm i node-red-node-serialport

During install there may be multiple messages about optional compilation.
These may look like failures... as they report as failure to compile errors -
but often are warnings and the node will continue to install and, assuming nothing else
failed, you should be able to use it. Occasionally some platforms *will* require
you to install the full set of tools in order to compile the underlying package.

## Usage

Provides three nodes - one to receive messages, and one to send, and a request node which can send then wait for a response.

### Input

Reads data from a local serial port.

Clicking on the search icon will attempt to autodetect serial ports attached to
the device, however you many need to manually specify it. COM1, /dev/ttyUSB0, etc

It can either

 - wait for a "split" character (default \n). Also accepts hex notation (0x0a).
 - wait for a timeout in milliseconds from the first character received
 - wait to fill a fixed sized buffer

It then outputs `msg.payload` as either a UTF8 ascii string or a binary Buffer object.

If no split character is specified, or a timeout or buffer size of 0, then a stream
of single characters is sent - again either as ascii chars or size 1 binary buffers.

### Output

Provides a connection to an outbound serial port.

Only the `msg.payload` is sent.

Optionally the character used to split the input can be appended to every message sent out to the serial port.

### Request

Provides a connection to a request/response serial port.

This node behaves as a tightly coupled combination of serial in and serial out nodes, with which it shares the configuration.

Send the request message in `msg.payload` as you would do with a serial out node. The message will be forwarded to the serial port following a strict FIFO (First In, First Out) queue, waiting for a single response before transmitting the next request. Once a response is received (with the same logic of a serial in node), or after a timeout occurs, a message is produced on the output, with msg.payload containing the received response (or missing in case if timeout), msg.status containing relevant info, and all other fields preserved.

For consistency with the serial in node, msg.port is also set to the name of the port selected.