MATLAB/Octave - RS232 Bricklet

Note

This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.

This is the description of the MATLAB/Octave 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 MATLAB/Octave API bindings is part of their general description.

Examples

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

API

Generally, every method of the MATLAB bindings that returns a value can throw a TimeoutException. This exception gets thrown if the device did not respond. If a cable based connection is used, it is unlikely that this exception gets thrown (assuming nobody unplugs the device). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.

Beside the TimeoutException there is also a NotConnectedException that is thrown if a method needs to communicate with the device while the IP Connection is not connected.

Since the MATLAB bindings are based on Java and Java does not support multiple return values and return by reference is not possible for primitive types, we use small classes that only consist of member variables. The member variables of the returned objects are described in the corresponding method descriptions.

The package for all Brick/Bricklet bindings and the IP Connection is com.tinkerforge.*

All methods listed below are thread-safe.

Basic Functions

public class BrickletRS232(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletRS232;

rs232 = BrickletRS232('YOUR_DEVICE_UID', ipcon);

In Octave:

rs232 = java_new("com.tinkerforge.BrickletRS232", "YOUR_DEVICE_UID", ipcon);

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

public short write(char[] message, short length)

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 SetConfigurations() for configuration possibilities regarding baudrate, parity and so on.

public BrickletRS232.Read read()

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 enableCallback() and ReadCallbackCallback.

The returned object has the public member variables char[] message and short length.

public void setConfiguration(short baudrate, short parity, short stopbits, short wordlength, short hardwareFlowcontrol, short softwareFlowcontrol)

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 each be on or off.

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_28800 = 7
  • BrickletRS232.BAUDRATE_38400 = 8
  • BrickletRS232.BAUDRATE_57600 = 9
  • BrickletRS232.BAUDRATE_115200 = 10
  • BrickletRS232.BAUDRATE_230400 = 11
  • 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
public BrickletRS232.Configuration getConfiguration()

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_28800 = 7
  • BrickletRS232.BAUDRATE_38400 = 8
  • BrickletRS232.BAUDRATE_57600 = 9
  • BrickletRS232.BAUDRATE_115200 = 10
  • BrickletRS232.BAUDRATE_230400 = 11
  • 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 object has the public member variables short baudrate, short parity, short stopbits, short wordlength, short hardwareFlowcontrol and short softwareFlowcontrol.

Advanced Functions

public short[] getAPIVersion()

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.

public boolean getResponseExpected(short functionId)

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.

public void setResponseExpected(short functionId, boolean responseExpected)

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 and callbacks it is always disabled.

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_CALLBACK = 3
  • BrickletRS232.FUNCTION_DISABLE_CALLBACK = 4
  • BrickletRS232.FUNCTION_SET_CONFIGURATION = 6
public void setResponseExpectedAll(boolean responseExpected)

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

public BrickletRS232.Identity getIdentity()

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 object has the public member variables String uid, String connectedUid, char position, short[] hardwareVersion, short[] firmwareVersion and int deviceIdentifier.

Callback Configuration Functions

public void enableCallback()

Enables the ReadCallbackCallback.

By default the callback is disabled.

public void disableCallback()

Disables the ReadCallbackCallback.

By default the callback is disabled.

public boolean isCallbackEnabled()

Returns true if the ReadCallbackCallback is enabled, false otherwise.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with "set" function of MATLAB. The parameters consist of the IP Connection object, the callback name and the callback function. For example, it looks like this in MATLAB:

function cb_example(e)
    fprintf('Parameter: %s\n', e.param);
end

set(device, 'ExampleCallback', @(h, e) cb_example(e));

Due to a difference in the Octave Java support the "set" function cannot be used in Octave. The registration is done with "add*Callback" functions of the device object. It looks like this in Octave:

function cb_example(e)
    fprintf("Parameter: %s\n", e.param);
end

device.addExampleCallback(@cb_example);

It is possible to add several callbacks and to remove them with the corresponding "remove*Callback" function.

The parameters of the callback are passed to the callback function as fields of the structure e, which is derived from the java.util.EventObject class. The available callback names with corresponding structure fields 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.

public callback BrickletRS232.ReadCallbackCallback
Parameters:
  • message -- char[]
  • length -- short

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 enableCallback().

In MATLAB the set() function can be used to register a callback function to this callback.

In Octave a callback function can be added to this callback using the addReadCallbackCallback() function. An added callback function can be removed with the removeReadCallbackCallback() function.

Constants

public static final int BrickletRS232.DEVICE_IDENTIFIER

This constant is used to identify a RS232 Bricklet.

The getIdentity() function and the EnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

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