Ruby - RS232 Bricklet

This is the description of the Ruby API bindings for the RS232 Bricklet. General information and technical specifications for the RS232 Bricklet are summarized in its hardware description.

An installation guide for the Ruby API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Loopback

Download (example_loopback.rb)

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#!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-

# For this example connect the RX1 and TX pin to receive the send message

require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_rs232'

include Tinkerforge

HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change XYZ to the UID of your RS232 Bricklet

# Convert string to char array with length 60, as needed by write
def string_to_char_array(message)
  chars = message.split(//)
  chars += ['\0']*(60 - message.length)
  return chars
end

# Assume that the message consists of ASCII characters and
# convert it from an array of chars to a string
def char_array_to_string(message, length)
  return message.slice(0, length).join('')
end

ipcon = IPConnection.new # Create IP connection
rs232 = BrickletRS232.new UID, ipcon # Create device object

ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected

# Register read callback
rs232.register_callback(BrickletRS232::CALLBACK_READ) do |message, length|
  puts "Message (Length: #{length}): #{char_array_to_string message, length}"
end

# Enable read callback
rs232.enable_read_callback

# Write "test" string
message = "test"
rs232.write string_to_char_array(message), message.length

puts 'Press key to exit'
$stdin.gets
ipcon.disconnect

API

All methods listed below are thread-safe.

Basic Functions

BrickletRS232::new(uid, ipcon) → rs232
Parameters:
  • uid -- str
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

rs232 = BrickletRS232.new 'YOUR_DEVICE_UID', ipcon

This object can then be used after the IP Connection is connected (see examples above).

BrickletRS232#write(message, length) → int
Parameters:
  • message -- [str, str, ..57x.., str]
  • length -- int

Writes a string of up to 60 characters to the RS232 interface. The string can be binary data, ASCII or similar is not necessary.

The length of the string has to be given as an additional parameter.

The return value is the number of bytes that could be written.

See #set_configuration for configuration possibilities regarding baudrate, parity and so on.

BrickletRS232#read → [[str, str, ..57x.., str], int]

Returns the currently buffered message. The maximum length of message is 60. If the length is given as 0, there was no new data available.

Instead of polling with this function, you can also use callbacks. See #enable_read_callback and ::CALLBACK_READ callback.

The returned array has the values message and length.

BrickletRS232#set_configuration(baudrate, parity, stopbits, wordlength, hardware_flowcontrol, software_flowcontrol) → nil
Parameters:
  • baudrate -- int
  • parity -- int
  • stopbits -- int
  • wordlength -- int
  • hardware_flowcontrol -- int
  • software_flowcontrol -- int

Sets the configuration for the RS232 communication. Available options:

  • Baudrate between 300 and 230400 baud.
  • Parity of none, odd, even or forced parity.
  • Stopbits can be 1 or 2.
  • Word length of 5 to 8.
  • Hard-/Software flow control can either be on or off but not both simultaneously on.

The default is: 115200 baud, parity none, 1 stop bit, word length 8, hard-/software flow control off.

The following constants are available for this function:

  • BrickletRS232::BAUDRATE_300 = 0
  • BrickletRS232::BAUDRATE_600 = 1
  • BrickletRS232::BAUDRATE_1200 = 2
  • BrickletRS232::BAUDRATE_2400 = 3
  • BrickletRS232::BAUDRATE_4800 = 4
  • BrickletRS232::BAUDRATE_9600 = 5
  • BrickletRS232::BAUDRATE_14400 = 6
  • BrickletRS232::BAUDRATE_19200 = 7
  • BrickletRS232::BAUDRATE_28800 = 8
  • BrickletRS232::BAUDRATE_38400 = 9
  • BrickletRS232::BAUDRATE_57600 = 10
  • BrickletRS232::BAUDRATE_115200 = 11
  • BrickletRS232::BAUDRATE_230400 = 12
  • BrickletRS232::PARITY_NONE = 0
  • BrickletRS232::PARITY_ODD = 1
  • BrickletRS232::PARITY_EVEN = 2
  • BrickletRS232::PARITY_FORCED_PARITY_1 = 3
  • BrickletRS232::PARITY_FORCED_PARITY_0 = 4
  • BrickletRS232::STOPBITS_1 = 1
  • BrickletRS232::STOPBITS_2 = 2
  • BrickletRS232::WORDLENGTH_5 = 5
  • BrickletRS232::WORDLENGTH_6 = 6
  • BrickletRS232::WORDLENGTH_7 = 7
  • BrickletRS232::WORDLENGTH_8 = 8
  • BrickletRS232::HARDWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232::HARDWARE_FLOWCONTROL_ON = 1
  • BrickletRS232::SOFTWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232::SOFTWARE_FLOWCONTROL_ON = 1
BrickletRS232#get_configuration → [int, int, int, int, int, int]

Returns the configuration as set by #set_configuration.

The following constants are available for this function:

  • BrickletRS232::BAUDRATE_300 = 0
  • BrickletRS232::BAUDRATE_600 = 1
  • BrickletRS232::BAUDRATE_1200 = 2
  • BrickletRS232::BAUDRATE_2400 = 3
  • BrickletRS232::BAUDRATE_4800 = 4
  • BrickletRS232::BAUDRATE_9600 = 5
  • BrickletRS232::BAUDRATE_14400 = 6
  • BrickletRS232::BAUDRATE_19200 = 7
  • BrickletRS232::BAUDRATE_28800 = 8
  • BrickletRS232::BAUDRATE_38400 = 9
  • BrickletRS232::BAUDRATE_57600 = 10
  • BrickletRS232::BAUDRATE_115200 = 11
  • BrickletRS232::BAUDRATE_230400 = 12
  • BrickletRS232::PARITY_NONE = 0
  • BrickletRS232::PARITY_ODD = 1
  • BrickletRS232::PARITY_EVEN = 2
  • BrickletRS232::PARITY_FORCED_PARITY_1 = 3
  • BrickletRS232::PARITY_FORCED_PARITY_0 = 4
  • BrickletRS232::STOPBITS_1 = 1
  • BrickletRS232::STOPBITS_2 = 2
  • BrickletRS232::WORDLENGTH_5 = 5
  • BrickletRS232::WORDLENGTH_6 = 6
  • BrickletRS232::WORDLENGTH_7 = 7
  • BrickletRS232::WORDLENGTH_8 = 8
  • BrickletRS232::HARDWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232::HARDWARE_FLOWCONTROL_ON = 1
  • BrickletRS232::SOFTWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232::SOFTWARE_FLOWCONTROL_ON = 1

The returned array has the values baudrate, parity, stopbits, wordlength, hardware_flowcontrol and software_flowcontrol.

BrickletRS232#set_break_condition(break_time) → nil
Parameters:break_time -- int

Sets a break condition (the TX output is forced to a logic 0 state). The parameter sets the hold-time of the break condition (in ms).

New in version 2.0.2 (Plugin).

Advanced Functions

BrickletRS232#get_api_version → [int, int, int]

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

BrickletRS232#get_response_expected(function_id) → bool
Parameters:function_id -- int

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by #set_response_expected. For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

See #set_response_expected for the list of function ID constants available for this function.

BrickletRS232#set_response_expected(function_id, response_expected) → nil
Parameters:
  • function_id -- int
  • response_expected -- bool

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following function ID constants are available for this function:

  • BrickletRS232::FUNCTION_ENABLE_READ_CALLBACK = 3
  • BrickletRS232::FUNCTION_DISABLE_READ_CALLBACK = 4
  • BrickletRS232::FUNCTION_SET_CONFIGURATION = 6
  • BrickletRS232::FUNCTION_SET_BREAK_CONDITION = 10
BrickletRS232#set_response_expected_all(response_expected) → nil
Parameters:response_expected -- bool

Changes the response expected flag for all setter and callback configuration functions of this device at once.

BrickletRS232#get_identity → [str, str, str, [int, int, int], [int, int, int], int]

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c' or 'd'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

The returned array has the values uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

Callback Configuration Functions

BrickletRS232#register_callback(callback_id) { |param [, ...]| block } → nil
Parameters:callback_id -- int

Registers the given block with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletRS232#enable_read_callback → nil

Enables the ::CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS232#disable_read_callback → nil

Disables the ::CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS232#is_read_callback_enabled → bool

Returns true if the ::CALLBACK_READ callback is enabled, false otherwise.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the #register_callback function of the device object. The first parameter is the callback ID and the second parameter is a block:

rs232.register_callback BrickletRS232::CALLBACK_EXAMPLE, do |param|
  puts "#{param}"
end

The available constants with inherent number and type of parameters are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

BrickletRS232::CALLBACK_READ
Parameters:
  • message -- [str, str, ..57x.., str]
  • length -- int

This callback is called if new data is available. The message has a maximum size of 60 characters. The actual length of the message is given in addition.

To enable this callback, use #enable_read_callback.

BrickletRS232::CALLBACK_ERROR
Parameters:error -- int

This callback is called if an error occurs. Possible errors are overrun, parity or framing error.

The following constants are available for this function:

  • BrickletRS232::ERROR_OVERRUN = 1
  • BrickletRS232::ERROR_PARITY = 2
  • BrickletRS232::ERROR_FRAMING = 4

New in version 2.0.1 (Plugin).

Constants

BrickletRS232::DEVICE_IDENTIFIER

This constant is used to identify a RS232 Bricklet.

The #get_identity() function and the ::CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickletRS232::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a RS232 Bricklet.