FFI Ruby library for RS-232 serial port communication
Latest commit 641e29f Jul 27, 2016 @deadprogram deadprogram Update gem version to 0.4.0
Signed-off-by: deadprogram <ron@hybridgroup.com>



RubySerial is a simple Ruby gem for reading from and writing to serial ports.

Unlike other Ruby serial port implementations, it supports all of the most popular Ruby implementations (MRI, JRuby, & Rubinius) on the most popular operating systems (OSX, Linux, & Windows). And it does not require any native compilation thanks to using RubyFFI https://github.com/ffi/ffi.

The interface to RubySerial should be (mostly) compatible with other Ruby serialport gems, so you should be able to drop in the new gem, change the require and use it as a replacement. If not, please let us know so we can address any issues.

Build Status Build status Test Coverage


$ gem install rubyserial


require 'rubyserial'
serialport = Serial.new '/dev/ttyACM0' # Defaults to 9600 baud, 8 data bits, and no parity
serialport = Serial.new '/dev/ttyACM0', 57600
serialport = Serial.new '/dev/ttyACM0', 19200, 8, :even


write(data : String) -> Int

Returns the number of bytes written. Emits a RubySerial::Exception on error.

read(length : Int) -> String

Returns a string up to length long. It is not guaranteed to return the entire length specified, and will return an empty string if no data is available. Emits a RubySerial::Exception on error.

getbyte -> Fixnum or nil

Returns an 8 bit byte or nil if no data is available. Emits a RubySerial::Exception on error.


A wrapper exception type, that returns the underlying system error code.

Running the tests

The test suite is written using rspec, just use the rspec command.

However, to run the tests, you must also have the socat utility program installed.

Installing socat on OS X

brew install socat

Installing socat on Linux

sudo apt-get install socat

Installing socat on Windows

You might need to build from source... the latest build of socat for Windows is quite old. Get source from here:



Apache 2.0. See LICENSE for more details.