JavaScript - RS232 Bricklet

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

Examples

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

Loopback (Node.js)

Download (ExampleLoopback.js)

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var Tinkerforge = require('tinkerforge');

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

var HOST = 'localhost';
var PORT = 4223;
var UID = 'XYZ'; // Change XYZ to the UID of your RS232 Bricklet

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var rs232 = new Tinkerforge.BrickletRS232(UID, ipcon); // Create device object

// Convert string to array of length 60 as needed by write
function stringToCharArray(message) {
    var array = [];
    for(var i = 0; i < message.length; i++) {
        array.push(message[i]);
    }
    for(var i = message.length; i < 60; i++) {
        array.push('\0');
    }
    return array
}

// Assume that the message consists of ASCII characters and
// convert it from an array of chars to a string
function charArrayToString(message, length) {
    return message.slice(0, length).join('');
}

ipcon.connect(HOST, PORT,
    function (error) {
        console.log('Error: ' + error);
    }
); // Connect to brickd
// Don't use device before ipcon is connected

ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
    function (connectReason) {
        // Enable read callback
        rs232.enableReadCallback();

        // Write "test" string
        var message = 'test';
        rs232.write(stringToCharArray(message), message.length);
    }
);

// Register read callback
rs232.on(Tinkerforge.BrickletRS232.CALLBACK_READ,
    // Callback function for read callback
    function (message, length) {
        var str = charArrayToString(message, length);
        console.log('Message (Length: ' + length + '): "' + str + '"');
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        ipcon.disconnect();
        process.exit(0);
    }
);

Loopback (HTML)

Download (ExampleLoopback.html), Test (ExampleLoopback.html)

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<!DOCTYPE html>

<!-- For this example connect the RX1 and TX pin to receive the send message -->

<html>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <head>
        <title>Tinkerforge | JavaScript Example</title>
    </head>
    <body>
        <div style="text-align:center;">
            <h1>RS232 Bricklet Loopback Example</h1>
            <p>
                <input value="localhost" id="host" type="text" size="20">:
                <input value="4280" id="port" type="text" size="5">,
                <input value="uid" id="uid" type="text" size="5">
                <input value="Start Example" id="start" type="button" onclick="startExample();">
            </p>
            <p>
                <textarea readonly id="text" cols="80" rows="24" style="resize:none;"
                          >Press "Start Example" to begin ...</textarea>
            </p>
        </div>
        <script src="./Tinkerforge.js" type='text/javascript'></script>
        <script type='text/javascript'>
            // Convert string to array of length 60 as needed by write
            function stringToCharArray(message) {
                var array = [];
                for(var i = 0; i < message.length; i++) {
                    array.push(message[i]);
                }
                for(var i = message.length; i < 60; i++) {
                    array.push('\0');
                }
                return array
            }

            // Assume that the message consists of ASCII characters and
            // convert it from an array of chars to a string
            function charArrayToString(message, len) {
                return message.slice(0, len).join('');
            }

            var ipcon;
            var textArea = document.getElementById("text");
            function startExample() {
                textArea.value = "";
                var HOST = document.getElementById("host").value;
                var PORT = parseInt(document.getElementById("port").value);
                var UID = document.getElementById("uid").value;
                if(ipcon !== undefined) {
                    ipcon.disconnect();
                }
                ipcon = new Tinkerforge.IPConnection(); // Create IP connection
                var rs232 = new Tinkerforge.BrickletRS232(UID, ipcon); // Create device object
                ipcon.connect(HOST, PORT,
                    function(error) {
                        textArea.value += 'Error: ' + error + '\n';
                    }
                ); // Connect to brickd
                // Don't use device before ipcon is connected

                ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
                    function (connectReason) {
                        // Enable read callback
                        rs232.enableReadCallback();

                        // Write "test" string
                        var message = 'test';
                        rs232.write(stringToCharArray(message), message.length);
                    }
                );

                // Register read callback
                rs232.on(Tinkerforge.BrickletRS232.CALLBACK_READ,
                    // Callback function for read callback
                    function (message, len) {
                        var str = charArrayToString(message, len);
                        textArea.value += 'Message (Length: ' + len + '): "' + str + '"\n';
                    }
                );
            }
        </script>
    </body>
</html>

API

Generally, every method of the JavaScript bindings can take two optional parameters, returnCallback and errorCallback. These are two user defined callback functions. The returnCallback is called with the return values as parameters, if the method returns something. The errorCallback is called with an error code in case of an error. The error code can be one of the following values:

  • IPConnection.ERROR_ALREADY_CONNECTED = 11
  • IPConnection.ERROR_NOT_CONNECTED = 12
  • IPConnection.ERROR_CONNECT_FAILED = 13
  • IPConnection.ERROR_INVALID_FUNCTION_ID = 21
  • IPConnection.ERROR_TIMEOUT = 31
  • IPConnection.ERROR_INVALID_PARAMETER = 41
  • IPConnection.ERROR_FUNCTION_NOT_SUPPORTED = 42
  • IPConnection.ERROR_UNKNOWN_ERROR = 43

The namespace for the JavaScript bindings is Tinkerforge.*.

Basic Functions

new BrickletRS232(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

var rs232 = new BrickletRS232("YOUR_DEVICE_UID", ipcon);

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

BrickletRS232.write(message, length[, returnCallback][, errorCallback])
Parameters:
  • message -- [char, char, ..57x.., char]
  • length -- int
Callback:
  • written -- 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 setConfiguration() for configuration possibilities regarding baudrate, parity and so on.

BrickletRS232.read([returnCallback][, errorCallback])
Callback:
  • message -- [char, char, ..57x.., char]
  • length -- 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 enableReadCallback() and CALLBACK_READ callback.

BrickletRS232.setConfiguration(baudrate, parity, stopbits, wordlength, hardwareFlowcontrol, softwareFlowcontrol[, returnCallback][, errorCallback])
Parameters:
  • baudrate -- int
  • parity -- int
  • stopbits -- int
  • wordlength -- int
  • hardwareFlowcontrol -- int
  • softwareFlowcontrol -- int
Callback:

undefined

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.getConfiguration([returnCallback][, errorCallback])
Callback:
  • baudrate -- int
  • parity -- int
  • stopbits -- int
  • wordlength -- int
  • hardwareFlowcontrol -- int
  • softwareFlowcontrol -- int

Returns the configuration as set by setConfiguration().

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.setBreakCondition(breakTime[, returnCallback][, errorCallback])
Parameters:
  • breakTime -- int
Callback:

undefined

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.getAPIVersion()
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.getResponseExpected(functionId[, errorCallback])
Parameters:
  • functionId -- int
Return type:

boolean

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 setResponseExpected(). 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 setResponseExpected() for the list of function ID constants available for this function.

BrickletRS232.setResponseExpected(functionId, responseExpected[, errorCallback])
Parameters:
  • functionId -- int
  • responseExpected -- boolean

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.setResponseExpectedAll(responseExpected)
Parameters:
  • responseExpected -- boolean

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

BrickletRS232.getIdentity([returnCallback][, errorCallback])
Callback:
  • uid -- string
  • connectedUid -- string
  • position -- char
  • hardwareVersion -- [int, int, int]
  • firmwareVersion -- [int, int, int]
  • deviceIdentifier -- 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.

Callback Configuration Functions

BrickletRS232.on(callback_id, function)
Parameters:
  • callback_id -- int
  • function -- function

Registers the given function with the given callback_id.

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

BrickletRS232.enableReadCallback([returnCallback][, errorCallback])
Callback:undefined

Enables the CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS232.disableReadCallback([returnCallback][, errorCallback])
Callback:undefined

Disables the CALLBACK_READ callback.

By default the callback is disabled.

BrickletRS232.isReadCallbackEnabled([returnCallback][, errorCallback])
Callback:
  • enabled -- boolean

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 on() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

rs232.on(BrickletRS232.CALLBACK_EXAMPLE,
    function (param) {
        console.log(param);
    }
);

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 enableReadCallback().

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 getIdentity() 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.