MATLAB/Octave - Dual Relay Bricklet

This is the description of the MATLAB/Octave API bindings for the Dual Relay Bricklet. General information and technical specifications for the Dual Relay 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).

Simple (MATLAB)

Download (matlab_example_simple.m)

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function matlab_example_simple()
    import com.tinkerforge.IPConnection;
    import com.tinkerforge.BrickletDualRelay;

    HOST = 'localhost';
    PORT = 4223;
    UID = 'XYZ'; % Change XYZ to the UID of your Dual Relay Bricklet

    ipcon = IPConnection(); % Create IP connection
    dr = handle(BrickletDualRelay(UID, ipcon), 'CallbackProperties'); % Create device object

    ipcon.connect(HOST, PORT); % Connect to brickd
    % Don't use device before ipcon is connected

    % Turn relays alternating on/off 10 times with 1 second delay
    for i = 0:4
        pause(1);
        dr.setState(true, false);
        pause(1);
        dr.setState(false, true);
    end

    input('Press key to exit\n', 's');
    ipcon.disconnect();
end

Simple (Octave)

Download (octave_example_simple.m)

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function octave_example_simple()
    more off;

    HOST = "localhost";
    PORT = 4223;
    UID = "XYZ"; % Change XYZ to the UID of your Dual Relay Bricklet

    ipcon = javaObject("com.tinkerforge.IPConnection"); % Create IP connection
    dr = javaObject("com.tinkerforge.BrickletDualRelay", UID, ipcon); % Create device object

    ipcon.connect(HOST, PORT); % Connect to brickd
    % Don't use device before ipcon is connected

    % Turn relays alternating on/off 10 times with 1 second delay
    for i = 0:4
        pause(1);
        dr.setState(true, false);
        pause(1);
        dr.setState(false, true);
    end

    input("Press key to exit\n", "s");
    ipcon.disconnect();
end

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 BrickletDualRelay(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid.

In MATLAB:

import com.tinkerforge.BrickletDualRelay;

dualRelay = BrickletDualRelay('YOUR_DEVICE_UID', ipcon);

In Octave:

dualRelay = java_new("com.tinkerforge.BrickletDualRelay", "YOUR_DEVICE_UID", ipcon);

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

public void setState(boolean relay1, boolean relay2)

Sets the state of the relays, true means on and false means off. For example: (true, false) turns relay 1 on and relay 2 off.

If you just want to set one of the relays and don't know the current state of the other relay, you can get the state with getState() or you can use setSelectedState().

Running monoflop timers will be overwritten if this function is called.

The default value is (false, false).

public BrickletDualRelay.State getState()

Returns the state of the relays, true means on and false means off.

The returned object has the public member variables boolean relay1 and boolean relay2.

Advanced Functions

public void setMonoflop(short relay, boolean state, long time)

The first parameter can be 1 or 2 (relay 1 or relay 2). The second parameter is the desired state of the relay (true means on and false means off). The third parameter indicates the time (in ms) that the relay should hold the state.

If this function is called with the parameters (1, true, 1500): Relay 1 will turn on and in 1.5s it will turn off again.

A monoflop can be used as a failsafe mechanism. For example: Lets assume you have a RS485 bus and a Dual Relay Bricklet connected to one of the slave stacks. You can now call this function every second, with a time parameter of two seconds. The relay will be on all the time. If now the RS485 connection is lost, the relay will turn off in at most two seconds.

public BrickletDualRelay.Monoflop getMonoflop(short relay)

Returns (for the given relay) the current state and the time as set by setMonoflop() as well as the remaining time until the state flips.

If the timer is not running currently, the remaining time will be returned as 0.

The returned object has the public member variables boolean state, long time and long timeRemaining.

public void setSelectedState(short relay, boolean state)

Sets the state of the selected relay (1 or 2), true means on and false means off.

The other relay remains untouched.

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.

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:

  • BrickletDualRelay.FUNCTION_SET_STATE = 1
  • BrickletDualRelay.FUNCTION_SET_MONOFLOP = 3
  • BrickletDualRelay.FUNCTION_SET_SELECTED_STATE = 6
public void setResponseExpectedAll(boolean responseExpected)

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

public BrickletDualRelay.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.

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

set(device, 'ExampleCallback', @(h, e) my_callback(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 my_callback(e)
    fprintf("Parameter: %s\n", e.param);
end

device.addExampleCallback(@my_callback);

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 BrickletDualRelay.MonoflopDoneCallback
Parameters:
  • relay -- short
  • state -- boolean

This callback is triggered whenever a monoflop timer reaches 0. The parameter contain the relay (1 or 2) and the current state of the relay (the state after the monoflop).

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 addMonoflopDoneCallback() function. An added callback function can be removed with the removeMonoflopDoneCallback() function.

Constants

public static final int BrickletDualRelay.DEVICE_IDENTIFIER

This constant is used to identify a Dual Relay 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.

public static final String BrickletDualRelay.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Dual Relay Bricklet.