Perl - RS232 Bricklet

This is the description of the Perl 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 Perl API bindings is part of their general description.

Examples

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

Loopback

Download (example_loopback.pl)

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#!/usr/bin/perl

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

use strict;
use Tinkerforge::IPConnection;
use Tinkerforge::BrickletRS232;

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

# Convert string to char array with length 60, as needed by write
sub string_to_char_array
{
    my ($message) = @_;

    my @chars = split('', $message);
    my @array = ("\0") x 60;

    for my $i (0..(scalar(@chars) - 1)) {
        $array[$i] = $chars[$i];
    }

    return \@array;
}

# Assume that the message consists of ASCII characters and
# convert it from an array of chars to a string
sub char_array_to_string
{
    my ($message, $length) = @_;

    return substr(join('', @{$message}), 0, $length);
}

# Callback subroutine for read callback
sub cb_read
{
    my ($message, $length) = @_;

    my $str = char_array_to_string($message, $length);
    print "Message (Length: " . $length . "): \"" . $str . "\"\n";
}

my $ipcon = Tinkerforge::IPConnection->new(); # Create IP connection
my $rs232 = Tinkerforge::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 to subroutine cb_read
$rs232->register_callback($rs232->CALLBACK_READ, 'cb_read');

# Enable read callback
$rs232->enable_read_callback();

# Write "test" string
my $message = string_to_char_array('test');
$rs232->write($message, 4);

print "Press key to exit\n";
<STDIN>;
$ipcon->disconnect();

API

Generally, every subroutine of the Perl bindings can report an error as Tinkerforge::Error object via croak(). The object has a get_code() and a get_message() subroutine. There are different error code:

  • Error->ALREADY_CONNECTED = 11
  • Error->NOT_CONNECTED = 12
  • Error->CONNECT_FAILED = 13
  • Error->INVALID_FUNCTION_ID = 21
  • Error->TIMEOUT = 31
  • Error->INVALID_PARAMETER = 41
  • Error->FUNCTION_NOT_SUPPORTED = 42
  • Error->UNKNOWN_ERROR = 43

All methods listed below are thread-safe.

Basic Functions

BrickletRS232->new($uid, $ipcon)
Parameters:
  • $uid -- string
  • $ipcon -- IPConnection
Return type:

BrickletRS232

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)
Parameters:
  • @message -- [char, char, ..57x.., char]
  • $length -- int
Return type:

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()
Return type:[[char, char, ..57x.., char], 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 contains the elements message and length.

BrickletRS232->set_configuration($baudrate, $parity, $stopbits, $wordlength, $hardware_flowcontrol, $software_flowcontrol)
Parameters:
  • $baudrate -- int
  • $parity -- int
  • $stopbits -- int
  • $wordlength -- int
  • $hardware_flowcontrol -- int
  • $software_flowcontrol -- int
Return type:

undef

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()
Return type:[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 contains the elements baudrate, parity, stopbits, wordlength, hardware_flowcontrol and software_flowcontrol.

BrickletRS232->set_break_condition($break_time)
Parameters:$break_time -- int
Return type:undef

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()
Return type:[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($function_id)
Parameters:$function_id -- int
Return type:bool

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)
Parameters:
  • $function_id -- int
  • $response_expected -- bool
Return type:

undef

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($response_expected)
Parameters:$response_expected -- bool
Return type:undef

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

BrickletRS232->get_identity()
Return type:[string, string, char, [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 contains the elements uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

Callback Configuration Functions

BrickletRS232->register_callback($id, $callback)
Parameters:
  • $id -- int
  • $callback -- string
Return type:

undef

Registers the given $function name with the given $callback_id.

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

BrickletRS232->enable_read_callback()
Return type:undef

Enables the CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS232->disable_read_callback()
Return type:undef

Disables the CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS232->is_read_callback_enabled()
Return type: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 the callback function name:

sub my_callback
{
    print "@_[0]";
}

$rs232->register_callback(BrickletRS232->CALLBACK_EXAMPLE, 'my_callback')

The callback function will be called from an internal thread of the IP Connection. In contrast to many other programming languages, variables are not automatically shared between threads in Perl. If you want to share a global variable between a callback function and the rest for your program it has to be marked as :shared. See the documentation of the threads::shared Perl module for more details.

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 -- [char, char, ..57x.., char]
  • $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.