Delphi/Lazarus - Solid State Relay Bricklet

This is the description of the Delphi/Lazarus 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 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, BrickletSolidStateRelay;

type
  TExample = class
  private
    ipcon: TIPConnection;
    ssr: TBrickletSolidStateRelay;
  public
    procedure Execute;
  end;

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

var
  e: TExample;

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

  { Create device object }
  ssr := TBrickletSolidStateRelay.Create(UID, ipcon);

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

  { Turn relay on/off 10 times with 1 second delay }
  for i := 0 to 4 do begin
    Sleep(1000);
    ssr.SetState(true);
    Sleep(1000);
    ssr.SetState(false);
  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 TBrickletSolidStateRelay.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

solidStateRelay := TBrickletSolidStateRelay.Create('YOUR_DEVICE_UID', ipcon);

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

procedure TBrickletSolidStateRelay.SetState(const state: boolean)

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.

function TBrickletSolidStateRelay.GetState: boolean

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

Advanced Functions

procedure TBrickletSolidStateRelay.SetMonoflop(const state: boolean; const time: longword)

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.

procedure TBrickletSolidStateRelay.GetMonoflop(out state: boolean; out time: longword; out timeRemaining: longword)

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.

function TBrickletSolidStateRelay.GetAPIVersion: array [0..2] of byte

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.

function TBrickletSolidStateRelay.GetResponseExpected(const functionId: byte): 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.

procedure TBrickletSolidStateRelay.SetResponseExpected(const functionId: byte; const 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:

  • BRICKLET_SOLID_STATE_RELAY_FUNCTION_SET_STATE = 1
  • BRICKLET_SOLID_STATE_RELAY_FUNCTION_SET_MONOFLOP = 3
procedure TBrickletSolidStateRelay.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletSolidStateRelay.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)

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

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: TBrickletSolidStateRelay; const param: word);
begin
  WriteLn(param);
end;

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

The available callback property and their 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.

property TBrickletSolidStateRelay.OnMonoflopDone
procedure(sender: TBrickletSolidStateRelay; const state: boolean) of object;

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

Constants

const BRICKLET_SOLID_STATE_RELAY_DEVICE_IDENTIFIER

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

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

const BRICKLET_SOLID_STATE_RELAY_DEVICE_DISPLAY_NAME

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