tio - a simple serial device I/O tool

1. Introduction

tio is a simple serial device tool which features a straightforward command-line and configuration file interface to easily connect to serial TTY devices for basic I/O operations.

1.1 Motivation

To make a simpler serial device tool for talking with serial TTY devices with less focus on classic terminal/modem features and more focus on the needs of embedded developers and hackers.

tio was originally created as an alternative to screen for connecting to serial devices when used in combination with tmux.

2. Features

• Easily connect to serial TTY devices
• Automatic connect and reconnect
• Sensible defaults (115200 8n1)
• Support for non-standard baud rates
• Support for mark and space parity
• X-modem (1K) and Y-modem file upload
• Support for RS-485 mode
• List available serial devices by ID
• Show RX/TX statistics
• Toggle serial lines
• Pulse serial lines with configurable pulse duration
• Local echo support
• Remapping of characters (nl, cr-nl, bs, lowercase to uppercase, etc.)
• Line timestamps
• Support for delayed output per character
• Support for delayed output per line
• Switchable independent input and output mode (normal vs hex)
• Log to file with automatic or manual naming of log file
• Configuration file support
• Activate sub-configurations by name or pattern
• Redirect I/O to UNIX socket or IPv4/v6 network socket for scripting or TTY sharing
• Pipe input and/or output
• Support for simple line request/response handling
• Bash completion on options, serial device names, and sub-configuration names
• Configurable text color
• Visual or audible alert on connect/disconnect
• Remapping of prefix key
• Support NO_COLOR env variable as per no-color.org
• Man page documentation
• Lua scripting support
  • Manipulate port control lines at connect/reconnect (useful for microcontroller reset/boot etc.)
  • Automate interaction with tty device (TBD)
• Plays nicely with tmux

3. Usage

For more usage details please see the man page documentation here.

3.1 Command-line

The command-line interface is straightforward as reflected in the output from 'tio --help':

Usage: tio [<options>] <tty-device|sub-config>

Connect to TTY device directly or via sub-configuration.

Options:
  -b, --baudrate <bps>                   Baud rate (default: 115200)
  -d, --databits 5|6|7|8                 Data bits (default: 8)
  -f, --flow hard|soft|none              Flow control (default: none)
  -s, --stopbits 1|2                     Stop bits (default: 1)
  -p, --parity odd|even|none|mark|space  Parity (default: none)
  -o, --output-delay <ms>                Output character delay (default: 0)
  -O, --output-line-delay <ms>           Output line delay (default: 0)
      --line-pulse-duration <duration>   Set line pulse duration
  -n, --no-autoconnect                   Disable automatic connect
  -e, --local-echo                       Enable local echo
      --input-mode normal|hex            Select input mode (default: normal)
      --output-mode normal|hex           Select output mode (default: normal)
  -t, --timestamp                        Enable line timestamp
      --timestamp-format <format>        Set timestamp format (default: 24hour)
  -L, --list-devices                     List available serial devices by ID
  -l, --log                              Enable log to file
      --log-file <filename>              Set log filename
      --log-directory <path>             Set log directory path for automatic named logs
      --log-append                       Append to log file
      --log-strip                        Strip control characters and escape sequences
  -m, --map <flags>                      Map characters
  -c, --color 0..255|bold|none|list      Colorize tio text (default: bold)
  -S, --socket <socket>                  Redirect I/O to socket
  -r, --response-wait                    Wait for line response then quit
      --response-timeout <ms>            Response timeout (default: 100)
      --rs-485                           Enable RS-485 mode
      --rs-485-config <config>           Set RS-485 configuration
      --alert bell|blink|none            Alert on connect/disconnect (default: none)
      --mute                             Mute tio
      --script <string>                  Run script from string
      --script-file <filename>           Run script from file
      --script-run once|always|never     Run script on connect (default: always)
  -v, --version                          Display version
  -h, --help                             Display help

Options and sub-configurations may be set via configuration file.

See the man page for more details.

By default tio automatically connects to the provided TTY device if present. If the device is not present, it will wait for it to appear and then connect. If the connection is lost (eg. device is unplugged), it will wait for the device to reappear and then reconnect. However, if the --no-autoconnect option is provided, tio will exit if the device is not present or an established connection is lost.

tio features full bash autocompletion.

3.1.1 Examples

Typical use is without options:

$ tio /dev/ttyUSB0

Which corresponds to the commonly used default options:

$ tio -b 115200 -d 8 -f none -s 1 -p none /dev/ttyUSB0

It is recommended to connect serial TTY devices by ID:

$ tio /dev/serial/by-id/usb-FTDI_TTL232R-3V3_FTGQVXBL-if00-port0

Using serial devices by ID ensures that tio automatically reconnects to the correct serial device if it is disconnected and then reconnected.

List available serial devices by ID:

$ tio --list-devices

Note: One can also use tio shell completion on /dev which will automatically list all available serial TTY devices.

Log to file with autogenerated filename:

$ tio --log /dev/ttyUSB0

Enable ISO8601 timestamps per line:

$ tio --timestamp --timestamp-format iso8601 /dev/ttyUSB0

Redirect I/O to IPv4 network socket on port 4242:

$ tio --socket inet:4242 /dev/ttyUSB0

Inject data to the serial device:

$ cat data.bin | tio /dev/ttyUSB0

Send command to serial device and wait for line response:

$ echo "*IDN?" | tio /dev/ttyACM0 --response-wait
KORAD KD3305P V4.2 SN:32475045

3.2 Key commands

Various in session key commands are supported. When tio is started, press ctrl-t ? to list the available key commands.

[15:02:53.269] Key commands:
[15:02:53.269]  ctrl-t ?       List available key commands
[15:02:53.269]  ctrl-t b       Send break
[15:02:53.269]  ctrl-t c       Show configuration
[15:02:53.269]  ctrl-t e       Toggle local echo mode
[15:02:53.269]  ctrl-t f       Toggle log to file
[15:02:53.269]  ctrl-t F       Flush data I/O buffers
[15:02:53.269]  ctrl-t g       Toggle serial port line
[15:02:53.269]  ctrl-t i       Toggle input mode
[15:02:53.269]  ctrl-t l       Clear screen
[15:02:53.269]  ctrl-t L       Show line states
[15:02:53.269]  ctrl-t m       Toggle MSB to LSB bit order
[15:02:53.269]  ctrl-t o       Toggle output mode
[15:02:53.269]  ctrl-t p       Pulse serial port line
[15:02:53.269]  ctrl-t q       Quit
[15:02:53.269]  ctrl-t r       Run script
[15:02:53.269]  ctrl-t s       Show statistics
[15:02:53.269]  ctrl-t t       Toggle line timestamp mode
[15:02:53.269]  ctrl-t U       Toggle conversion to uppercase on output
[15:02:53.269]  ctrl-t v       Show version
[15:02:53.269]  ctrl-t x       Send file via Xmodem-1K
[15:02:53.269]  ctrl-t X       Send file via Xmodem-CRC
[15:02:53.269]  ctrl-t y       Send file via Ymodem
[15:02:53.269]  ctrl-t ctrl-t Send ctrl-t character

If needed, the prefix key (ctrl-t) can be remapped via configuration file.

3.3 Configuration file

Options can be set via the configuration file first found in any of the following locations in the order listed:

• $XDG_CONFIG_HOME/tio/config
• $HOME/.config/tio/config
• $HOME/.tioconfig

The configuration file supports sub-configurations using named sections which can be activated via the command-line by name or pattern. A sub-configuration specifies which TTY device to connect to and other options.

Example configuration file:

# Defaults
baudrate = 9600
databits = 8
parity = none
stopbits = 1
color = 10

[rpi3]
device = /dev/serial/by-id/usb-FTDI_TTL232R-3V3_FTGQVXBL-if00-port0
baudrate = 115200
no-autoconnect = enable
log = enable
log-file = rpi3.log
line-pulse-duration = DTR=200,RTS=150
color = 12

[usb devices]
pattern = usb([0-9]*)
device = /dev/ttyUSB%s
color = 13

To use a specific sub-configuration by name simply start tio like so:

$ tio rpi3

Or by pattern match:

$ tio usb12

Another more elaborate configuration file example is available here.

4. Installation

4.1 Installation using package manager (Linux)

Packages for various GNU/Linux distributions are available. Please consult your package manager tool to find and install tio.

If you would like to see tio included in your favorite distribution, please reach out to its package maintainers team.

4.2 Installation using snap (Linux)

Install latest stable version:

$ snap install tio --classic

Note: Classic confinement is currently required due to limitations of the snapcraft framework. See Issue #187 for discussion.

4.3 Installation using brew (MacOS, Linux)

If you have brew installed:

$ brew install tio

4.4 Installation using MSYS2 (Windows)

If you have MSYS2 installed:

$ pacman -S tio

4.5 Installation from source

The latest source releases can be found here.

Install steps:

$ meson setup build
$ meson compile -C build
$ meson install -C build

See meson_options.txt for tio specific build options.

Note: The meson install steps may differ depending on your specific system.

4.6 Known issues

Getting permission access errors trying to open your serial device?

Add your user to the group which allows serial device access. For example, to add your user to the 'dialout' group do:

$ sudo usermod -a -G dialout <username>

5. Contributing

tio is open source. If you want to help out with the project please feel free to join in.

All contributions (bug reports, code, doc, ideas, etc.) are welcome.

Please use the github issue tracker and pull request features.

Also, if you find this free open source software useful please feel free to consider making a donation of your choice:

6. Support

Submit bug reports via GitHub: https://github.com/tio/tio/issues

7. Website

Visit tio.github.io

8. License

tio is GPLv2+. See LICENSE file for more details.

9. Authors

Created by Martin Lund <[email protected]>

See the AUTHORS file for full list of contributors.