Java - Solid State Relay Bricklet

This is the description of the Java API bindings for the Solid State Relay Bricklet. General information and technical specifications for the Solid State Relay Bricklet are summarized in its hardware description.

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


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


Download (

import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletSolidStateRelay;

public class ExampleSimple {
    private static final String HOST = "localhost";
    private static final int PORT = 4223;

    // Change XYZ to the UID of your Solid State Relay Bricklet
    private static final String UID = "XYZ";

    // Note: To make the example code cleaner we do not handle exceptions. Exceptions
    //       you might normally want to catch are described in the documentation
    public static void main(String args[]) throws Exception {
        IPConnection ipcon = new IPConnection(); // Create IP connection
        BrickletSolidStateRelay ssr =
          new BrickletSolidStateRelay(UID, ipcon); // Create device object

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

        // Turn relay on/off 10 times with 1 second delay
        for(int i = 0; i < 5; i++) {

        System.out.println("Press key to exit");;


Generally, every method of the Java 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 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 BrickletSolidStateRelay(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid:

BrickletSolidStateRelay solidStateRelay = new BrickletSolidStateRelay("YOUR_DEVICE_UID", ipcon);

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

public void setState(boolean state)

Sets the state of the relays true means on and false means off.

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

The default value is false.

public boolean getState()

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

Advanced Functions

public void setMonoflop(boolean state, long time)

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

If this function is called with the parameters (true, 1500): The relay 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 Solid State 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 BrickletSolidStateRelay.Monoflop getMonoflop()

Returns 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 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 listener 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 listener 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:

  • BrickletSolidStateRelay.FUNCTION_SET_STATE = 1
  • BrickletSolidStateRelay.FUNCTION_SET_MONOFLOP = 3
public void setResponseExpectedAll(boolean responseExpected)

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

public BrickletSolidStateRelay.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.


Listeners can be registered to receive time critical or recurring data from the device. The registration is done with "add*Listener" functions of the device object.

The parameter is a listener class object, for example:

device.addExampleListener(new BrickletSolidStateRelay.ExampleListener() {
    public void property(int value) {
        System.out.println("Value: " + value);

The available listener classes with inherent methods to be overwritten are described below. It is possible to add several listeners and to remove them with the corresponding "remove*Listener" function.


Using listeners 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 class BrickletSolidStateRelay.MonoflopDoneListener()

This listener can be added with the addMonoflopDoneListener() function. An added listener can be removed with the removeMonoflopDoneListener() function.

public void monoflopDone(boolean state)

This listener is triggered whenever the monoflop timer reaches 0. The parameter is the current state of the relay (the state after the monoflop).


public static final int BrickletSolidStateRelay.DEVICE_IDENTIFIER

This constant is used to identify a Solid State Relay Bricklet.

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

public static final String BrickletSolidStateRelay.DEVICE_DISPLAY_NAME

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