Delphi/Lazarus - Dual Relay Bricklet

This is the description of the Delphi/Lazarus 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 Delphi/Lazarus API bindings is part of their general description.

Examples

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

Simple

Download (ExampleSimple.pas)

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program ExampleSimple;

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickletDualRelay;

type
  TExample = class
  private
    ipcon: TIPConnection;
    dr: TBrickletDualRelay;
  public
    procedure Execute;
  end;

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

var
  e: TExample;

procedure TExample.Execute;
var i: integer;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  dr := TBrickletDualRelay.Create(UID, ipcon);

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

  { Turn relays alternating on/off 10 times with 1 second delay }
  for i := 0 to 4 do begin
    Sleep(1000);
    dr.SetState(true, false);
    Sleep(1000);
    dr.SetState(false, true);
  end;

  WriteLn('Press key to exit');
  ReadLn;
  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

API

Since Delphi does not support multiple return values directly, we use the out keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

Basic Functions

constructor TBrickletDualRelay.Create(const uid: string; ipcon: TIPConnection)
Parameters:
  • uid – Type: string
  • ipcon – Type: TIPConnection
Returns:
  • dualRelay – Type: TBrickletDualRelay

Creates an object with the unique device ID uid:

dualRelay := TBrickletDualRelay.Create('YOUR_DEVICE_UID', ipcon);

This object can then be used after the IP Connection is connected.

procedure TBrickletDualRelay.SetState(const relay1: boolean; const relay2: boolean)
Parameters:
  • relay1 – Type: boolean, Default: false
  • relay2 – Type: boolean, Default: false

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.

All running monoflop timers will be aborted if this function is called.

procedure TBrickletDualRelay.GetState(out relay1: boolean; out relay2: boolean)
Output Parameters:
  • relay1 – Type: boolean, Default: false
  • relay2 – Type: boolean, Default: false

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

Advanced Functions

procedure TBrickletDualRelay.SetMonoflop(const relay: byte; const state: boolean; const time: longword)
Parameters:
  • relay – Type: byte, Range: [1 to 2]
  • state – Type: boolean
  • time – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1]

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 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.

procedure TBrickletDualRelay.GetMonoflop(const relay: byte; out state: boolean; out time: longword; out timeRemaining: longword)
Parameters:
  • relay – Type: byte, Range: [1 to 2]
Output Parameters:
  • state – Type: boolean
  • time – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1]
  • timeRemaining – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1]

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.

procedure TBrickletDualRelay.SetSelectedState(const relay: byte; const state: boolean)
Parameters:
  • relay – Type: byte, Range: [1 to 2]
  • state – Type: boolean

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

A running monoflop timer for the selected relay will be aborted if this function is called.

The other relay remains untouched.

procedure TBrickletDualRelay.GetIdentity(out uid: string; out connectedUid: string; out position: char; out hardwareVersion: array [0..2] of byte; out firmwareVersion: array [0..2] of byte; out deviceIdentifier: word)
Output Parameters:
  • uid – Type: string, Length: up to 8
  • connectedUid – Type: string, Length: up to 8
  • position – Type: char, Range: ['a' to 'h', 'z']
  • hardwareVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]
  • firmwareVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]
  • deviceIdentifier – Type: word, Range: [0 to 216 - 1]

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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done by assigning a procedure to an callback property of the device object:

procedure TExample.MyCallback(sender: TBrickletDualRelay; const value: longint);
begin
  WriteLn(Format('Value: %d', [value]));
end;

dualRelay.OnExample := {$ifdef FPC}@{$endif}example.MyCallback;

The available callback properties and their parameter types 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.

property TBrickletDualRelay.OnMonoflopDone
procedure(sender: TBrickletDualRelay; const relay: byte; const state: boolean) of object;
Callback Parameters:
  • sender – Type: TBrickletDualRelay
  • relay – Type: byte, Range: [1 to 2]
  • state – Type: 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).

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

function TBrickletDualRelay.GetAPIVersion: array [0..2] of byte
Output Parameters:
  • apiVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]

Returns the version of the API definition 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.

function TBrickletDualRelay.GetResponseExpected(const functionId: byte): boolean
Parameters:
  • functionId – Type: byte, Range: See constants
Returns:
  • responseExpected – 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BRICKLET_DUAL_RELAY_FUNCTION_SET_STATE = 1
  • BRICKLET_DUAL_RELAY_FUNCTION_SET_MONOFLOP = 3
  • BRICKLET_DUAL_RELAY_FUNCTION_SET_SELECTED_STATE = 6
procedure TBrickletDualRelay.SetResponseExpected(const functionId: byte; const responseExpected: boolean)
Parameters:
  • functionId – Type: byte, Range: See constants
  • responseExpected – Type: 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BRICKLET_DUAL_RELAY_FUNCTION_SET_STATE = 1
  • BRICKLET_DUAL_RELAY_FUNCTION_SET_MONOFLOP = 3
  • BRICKLET_DUAL_RELAY_FUNCTION_SET_SELECTED_STATE = 6
procedure TBrickletDualRelay.SetResponseExpectedAll(const responseExpected: boolean)
Parameters:
  • responseExpected – Type: boolean

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

Constants

const BRICKLET_DUAL_RELAY_DEVICE_IDENTIFIER

This constant is used to identify a Dual Relay Bricklet.

The GetIdentity function and the TIPConnection.OnEnumerate callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

const BRICKLET_DUAL_RELAY_DEVICE_DISPLAY_NAME

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