Delphi/Lazarus - RS485 Bricklet

This is the description of the Delphi/Lazarus API bindings for the RS485 Bricklet. General information and technical specifications for the RS485 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).

Loopback

Download (ExampleLoopback.pas)

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program ExampleLoopback;

{ For this example connect the RX+/- pins to TX+/- pins on the same Bricklet
  and configure the DIP switch on the Bricklet to full-duplex mode }

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

uses
  SysUtils, IPConnection, BrickletRS485;

type
  TExample = class
  private
    ipcon: TIPConnection;
    rs485: TBrickletRS485;
  public
    procedure ReadCB(sender: TBrickletRS485; const message_: TArrayOfChar);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your RS485 Bricklet }

var
  e: TExample;

{ Callback procedure for read callback }
procedure TExample.ReadCB(sender: TBrickletRS485; const message_: TArrayOfChar);
var str: string;
begin
  { Assume that the message consists of ASCII characters and
    convert it from an array of chars to a string }
  SetString(str, PChar(@message_[0]), Length(message_));
  WriteLn(Format('Message: "%s"', [str]));
end;

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

  { Create device object }
  rs485 := TBrickletRS485.Create(UID, ipcon);

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

  { Enable full-duplex mode }
  rs485.SetRS485Configuration(115200, BRICKLET_RS485_PARITY_NONE,
                              BRICKLET_RS485_STOPBITS_1, BRICKLET_RS485_WORDLENGTH_8,
                              BRICKLET_RS485_DUPLEX_FULL);

  { Register read callback to procedure ReadCB }
  rs485.OnRead := {$ifdef FPC}@{$endif}ReadCB;

  { Enable read callback }
  rs485.EnableReadCallback;

  { Write "test" string }
  rs485.Write(['t', 'e', 's', 't']);

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

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

Modbus Master

Download (ExampleModbusMaster.pas)

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program ExampleModbusMaster;

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

uses
  SysUtils, IPConnection, BrickletRS485;

type
  TExample = class
  private
    ipcon: TIPConnection;
    rs485: TBrickletRS485;
  public
    procedure ModbusMasterWriteSingleRegisterResponseCB(sender: TBrickletRS485;
                                                        const requestID: byte;
                                                        const exceptionCode: shortint);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your RS485 Bricklet }

var
  e: TExample;
  expectedRequestID: byte;

{ Callback procedure for Modbus master write single register response callback }
procedure TExample.ModbusMasterWriteSingleRegisterResponseCB(sender: TBrickletRS485;
                                                             const requestID: byte;
                                                             const exceptionCode: shortint);
begin
  WriteLn(Format('Request ID: %d', [requestID]));
  WriteLn(Format('Exception Code: %d', [exceptionCode]));

  if (requestID <> expectedRequestID) then begin
    WriteLn('Error: Unexpected request ID');
  end;
end;

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

  { Create device object }
  rs485 := TBrickletRS485.Create(UID, ipcon);

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

  { Set operating mode to Modbus RTU master }
  rs485.SetMode(BRICKLET_RS485_MODE_MODBUS_MASTER_RTU);

  { Modbus specific configuration:
    - slave address = 1 (unused in master mode)
    - master request timeout = 1000ms }
  rs485.SetModbusConfiguration(1, 1000);

  { Register Modbus master write single register response callback to procedure
    ModbusMasterWriteSingleRegisterResponseCB }
  rs485.OnModbusMasterWriteSingleRegisterResponse := {$ifdef FPC}@{$endif}ModbusMasterWriteSingleRegisterResponseCB;

  { Write 65535 to register 42 of slave 17 }
  expectedRequestID := rs485.ModbusMasterWriteSingleRegister(17, 42, 65535);

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

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

Modbus Slave

Download (ExampleModbusSlave.pas)

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program ExampleModbusSlave;

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

uses
  SysUtils, IPConnection, BrickletRS485;

type
  TExample = class
  private
    ipcon: TIPConnection;
    rs485: TBrickletRS485;
  public
    procedure ModbusSlaveWriteSingleRegisterRequestCB(sender: TBrickletRS485;
                                                      const requestID: byte;
                                                      const registerAddress: longword;
                                                      const registerValue: word);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your RS485 Bricklet }

var
  e: TExample;

{ Callback procedure for Modbus slave write single register request callback }
procedure TExample.ModbusSlaveWriteSingleRegisterRequestCB(sender: TBrickletRS485;
                                                           const requestID: byte;
                                                           const registerAddress: longword;
                                                           const registerValue: word);
begin
  WriteLn(Format('Request ID: %d', [requestID]));
  WriteLn(Format('Register Address: %d', [registerAddress]));
  WriteLn(Format('Register Value: %d', [registerValue]));

  if (registerAddress <> 42) then begin
    WriteLn('Error: Invalid register address');
    sender.ModbusSlaveReportException(requestID, BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS);
  end
  else begin
    sender.ModbusSlaveAnswerWriteSingleRegisterRequest(requestID);
  end
end;

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

  { Create device object }
  rs485 := TBrickletRS485.Create(UID, ipcon);

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

  { Set operating mode to Modbus RTU slave }
  rs485.SetMode(BRICKLET_RS485_MODE_MODBUS_SLAVE_RTU);

  { Modbus specific configuration:
    - slave address = 17
    - master request timeout = 0ms (unused in slave mode) }
  rs485.SetModbusConfiguration(17, 0);

  { Register Modbus slave write single register request callback to procedure
    ModbusSlaveWriteSingleRegisterRequestCB }
  rs485.OnModbusSlaveWriteSingleRegisterRequest := {$ifdef FPC}@{$endif}ModbusSlaveWriteSingleRegisterRequestCB;

  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 TBrickletRS485.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

rs485 := TBrickletRS485.Create('YOUR_DEVICE_UID', ipcon);

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

function TBrickletRS485.WriteLowLevel(const messageLength: word; const messageChunkOffset: word; const messageChunkData: array [0..59] of char): byte

Writes characters to the RS485 interface. The characters can be binary data, ASCII or similar is not necessary.

The return value is the number of characters that were written.

See SetRS485Configuration for configuration possibilities regarding baudrate, parity and so on.

procedure TBrickletRS485.ReadLowLevel(const length: word; out messageLength: word; out messageChunkOffset: word; out messageChunkData: array [0..59] of char)

Returns up to length characters from receive buffer.

Instead of polling with this function, you can also use callbacks. But note that this function will return available data only when the read callback is disabled. See EnableReadCallback and OnRead callback.

procedure TBrickletRS485.SetRS485Configuration(const baudrate: longword; const parity: byte; const stopbits: byte; const wordlength: byte; const duplex: byte)

Sets the configuration for the RS485 communication. Available options:

  • Baudrate between 100 and 2000000 baud.
  • Parity of none, odd or even.
  • Stopbits can be 1 or 2.
  • Word length of 5 to 8.
  • Half- or Full-Duplex.

The default is: 115200 baud, parity none, 1 stop bit, word length 8, half duplex.

The following constants are available for this function:

  • BRICKLET_RS485_PARITY_NONE = 0
  • BRICKLET_RS485_PARITY_ODD = 1
  • BRICKLET_RS485_PARITY_EVEN = 2
  • BRICKLET_RS485_STOPBITS_1 = 1
  • BRICKLET_RS485_STOPBITS_2 = 2
  • BRICKLET_RS485_WORDLENGTH_5 = 5
  • BRICKLET_RS485_WORDLENGTH_6 = 6
  • BRICKLET_RS485_WORDLENGTH_7 = 7
  • BRICKLET_RS485_WORDLENGTH_8 = 8
  • BRICKLET_RS485_DUPLEX_HALF = 0
  • BRICKLET_RS485_DUPLEX_FULL = 1
procedure TBrickletRS485.GetRS485Configuration(out baudrate: longword; out parity: byte; out stopbits: byte; out wordlength: byte; out duplex: byte)

Returns the configuration as set by SetRS485Configuration.

The following constants are available for this function:

  • BRICKLET_RS485_PARITY_NONE = 0
  • BRICKLET_RS485_PARITY_ODD = 1
  • BRICKLET_RS485_PARITY_EVEN = 2
  • BRICKLET_RS485_STOPBITS_1 = 1
  • BRICKLET_RS485_STOPBITS_2 = 2
  • BRICKLET_RS485_WORDLENGTH_5 = 5
  • BRICKLET_RS485_WORDLENGTH_6 = 6
  • BRICKLET_RS485_WORDLENGTH_7 = 7
  • BRICKLET_RS485_WORDLENGTH_8 = 8
  • BRICKLET_RS485_DUPLEX_HALF = 0
  • BRICKLET_RS485_DUPLEX_FULL = 1
procedure TBrickletRS485.SetModbusConfiguration(const slaveAddress: byte; const masterRequestTimeout: longword)

Sets the configuration for the RS485 Modbus communication. Available options:

  • Slave Address: Address to be used as the Modbus slave address in Modbus slave mode. Valid Modbus slave address range is 1 to 247.
  • Master Request Timeout: Specifies how long the master should wait for a response from a slave in milliseconds when in Modbus master mode.

The default is: Slave Address = 1 and Master Request Timeout = 1000 milliseconds (1 second).

procedure TBrickletRS485.GetModbusConfiguration(out slaveAddress: byte; out masterRequestTimeout: longword)

Returns the configuration as set by SetModbusConfiguration.

procedure TBrickletRS485.SetMode(const mode: byte)

Sets the mode of the Bricklet in which it operates. Available options are

  • RS485,
  • Modbus Master RTU and
  • Modbus Slave RTU.

The default is: RS485 mode.

The following constants are available for this function:

  • BRICKLET_RS485_MODE_RS485 = 0
  • BRICKLET_RS485_MODE_MODBUS_MASTER_RTU = 1
  • BRICKLET_RS485_MODE_MODBUS_SLAVE_RTU = 2
function TBrickletRS485.GetMode: byte

Returns the configuration as set by SetMode.

The following constants are available for this function:

  • BRICKLET_RS485_MODE_RS485 = 0
  • BRICKLET_RS485_MODE_MODBUS_MASTER_RTU = 1
  • BRICKLET_RS485_MODE_MODBUS_SLAVE_RTU = 2

Advanced Functions

procedure TBrickletRS485.SetCommunicationLEDConfig(const config: byte)

Sets the communication LED configuration. By default the LED shows RS485 communication traffic by flickering.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_OFF = 0
  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_ON = 1
  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
function TBrickletRS485.GetCommunicationLEDConfig: byte

Returns the configuration as set by SetCommunicationLEDConfig

The following constants are available for this function:

  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_OFF = 0
  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_ON = 1
  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_RS485_COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
procedure TBrickletRS485.SetErrorLEDConfig(const config: byte)

Sets the error LED configuration.

By default the error LED turns on if there is any error (see OnErrorCount callback). If you call this function with the SHOW ERROR option again, the LED will turn off until the next error occurs.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

  • BRICKLET_RS485_ERROR_LED_CONFIG_OFF = 0
  • BRICKLET_RS485_ERROR_LED_CONFIG_ON = 1
  • BRICKLET_RS485_ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_RS485_ERROR_LED_CONFIG_SHOW_ERROR = 3
function TBrickletRS485.GetErrorLEDConfig: byte

Returns the configuration as set by SetErrorLEDConfig.

The following constants are available for this function:

  • BRICKLET_RS485_ERROR_LED_CONFIG_OFF = 0
  • BRICKLET_RS485_ERROR_LED_CONFIG_ON = 1
  • BRICKLET_RS485_ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_RS485_ERROR_LED_CONFIG_SHOW_ERROR = 3
procedure TBrickletRS485.SetBufferConfig(const sendBufferSize: word; const receiveBufferSize: word)

Sets the send and receive buffer size in byte. In sum there is 10240 byte (10kb) buffer available and the minimum buffer size is 1024 byte (1kb) for both.

The current buffer content is lost if this function is called.

The send buffer holds data that was given by Write and could not be written yet. The receive buffer holds data that is received through RS485 but could not yet be send to the user, either by Read or through OnRead callback.

The default configuration is 5120 byte (5kb) per buffer.

procedure TBrickletRS485.GetBufferConfig(out sendBufferSize: word; out receiveBufferSize: word)

Returns the buffer configuration as set by SetBufferConfig.

procedure TBrickletRS485.GetBufferStatus(out sendBufferUsed: word; out receiveBufferUsed: word)

Returns the currently used bytes for the send and received buffer.

See SetBufferConfig for buffer size configuration.

procedure TBrickletRS485.GetErrorCount(out overrunErrorCount: longword; out parityErrorCount: longword)

Returns the current number of overrun and parity errors.

procedure TBrickletRS485.GetModbusCommonErrorCount(out timeoutErrorCount: longword; out checksumErrorCount: longword; out frameTooBigErrorCount: longword; out illegalFunctionErrorCount: longword; out illegalDataAddressErrorCount: longword; out illegalDataValueErrorCount: longword; out slaveDeviceFailureErrorCount: longword)

Returns the current number of errors occurred in Modbus mode.

  • Timeout Error Count: Number of timeouts occurred.
  • Checksum Error Count: Number of failures due to Modbus frame CRC16 checksum mismatch.
  • Frame Too Big Error Count: Number of times frames were rejected because they exceeded maximum Modbus frame size which is 256 bytes.
  • Illegal Function Error Count: Number of errors when an unimplemented or illegal function is requested. This corresponds to Modbus exception code 1.
  • Illegal Data Address Error Count: Number of errors due to invalid data address. This corresponds to Modbus exception code 2.
  • Illegal Data Value Error Count: Number of errors due to invalid data value. This corresponds to Modbus exception code 3.
  • Slave Device Failure Error Count: Number of errors occurred on the slave device which were unrecoverable. This corresponds to Modbus exception code 4.
procedure TBrickletRS485.ModbusSlaveReportException(const requestID: byte; const exceptionCode: shortint)

In Modbus slave mode this function can be used to report a Modbus exception for a Modbus master request.

  • Request ID: Request ID of the request received by the slave.
  • Exception Code: Modbus exception code to report to the Modbus master.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
procedure TBrickletRS485.ModbusSlaveAnswerReadCoilsRequestLowLevel(const requestID: byte; const coilsLength: word; const coilsChunkOffset: word; const coilsChunkData: array [0..471] of boolean)

In Modbus slave mode this function can be used to answer a master request to read coils.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Coils: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the OnModbusSlaveReadCoilsRequest callback with the Request ID as provided by the argument of the callback.

function TBrickletRS485.ModbusMasterReadCoils(const slaveAddress: byte; const startingAddress: longword; const count: word): byte

In Modbus master mode this function can be used to read coils from a slave. This function creates a Modbus function code 1 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Starting address of the read.
  • Count: Number of coils to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterReadCoilsResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

procedure TBrickletRS485.ModbusSlaveAnswerReadHoldingRegistersRequestLowLevel(const requestID: byte; const holdingRegistersLength: word; const holdingRegistersChunkOffset: word; const holdingRegistersChunkData: array [0..28] of word)

In Modbus slave mode this function can be used to answer a master request to read holding registers.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Holding Registers: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the OnModbusSlaveReadHoldingRegistersRequest callback with the Request ID as provided by the argument of the callback.

function TBrickletRS485.ModbusMasterReadHoldingRegisters(const slaveAddress: byte; const startingAddress: longword; const count: word): byte

In Modbus master mode this function can be used to read holding registers from a slave. This function creates a Modbus function code 3 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Starting address of the read.
  • Count: Number of holding registers to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterReadHoldingRegistersResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

procedure TBrickletRS485.ModbusSlaveAnswerWriteSingleCoilRequest(const requestID: byte)

In Modbus slave mode this function can be used to answer a master request to write a single coil.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the OnModbusSlaveWriteSingleCoilRequest callback with the Request ID as provided by the arguments of the callback.

function TBrickletRS485.ModbusMasterWriteSingleCoil(const slaveAddress: byte; const coilAddress: longword; const coilValue: boolean): byte

In Modbus master mode this function can be used to write a single coil of a slave. This function creates a Modbus function code 5 request.

  • Slave Address: Address of the target Modbus slave.
  • Coil Address: Address of the coil.
  • Coil Value: Value to be written.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterWriteSingleCoilResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

procedure TBrickletRS485.ModbusSlaveAnswerWriteSingleRegisterRequest(const requestID: byte)

In Modbus slave mode this function can be used to answer a master request to write a single register.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the OnModbusSlaveWriteSingleRegisterRequest callback with the Request ID, Register Address and Register Value as provided by the arguments of the callback.

function TBrickletRS485.ModbusMasterWriteSingleRegister(const slaveAddress: byte; const registerAddress: longword; const registerValue: word): byte

In Modbus master mode this function can be used to write a single register of a slave. This function creates a Modbus function code 6 request.

  • Slave Address: Address of the target Modbus slave.
  • Register Address: Address of the register.
  • Register Value: Value to be written.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterWriteSingleRegisterResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

procedure TBrickletRS485.ModbusSlaveAnswerWriteMultipleCoilsRequest(const requestID: byte)

In Modbus slave mode this function can be used to answer a master request to write multiple coils.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the OnModbusSlaveWriteMultipleCoilsRequest callback with the Request ID of the callback.

function TBrickletRS485.ModbusMasterWriteMultipleCoilsLowLevel(const slaveAddress: byte; const startingAddress: longword; const coilsLength: word; const coilsChunkOffset: word; const coilsChunkData: array [0..439] of boolean): byte

In Modbus master mode this function can be used to write multiple coils of a slave. This function creates a Modbus function code 15 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Starting address of the write.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterWriteMultipleCoilsResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

procedure TBrickletRS485.ModbusSlaveAnswerWriteMultipleRegistersRequest(const requestID: byte)

In Modbus slave mode this function can be used to answer a master request to write multiple registers.

  • Request ID: Request ID of the corresponding request that is being answered.

This function must be called from the OnModbusSlaveWriteMultipleRegistersRequest callback with the Request ID of the callback.

function TBrickletRS485.ModbusMasterWriteMultipleRegistersLowLevel(const slaveAddress: byte; const startingAddress: longword; const registersLength: word; const registersChunkOffset: word; const registersChunkData: array [0..26] of word): byte

In Modbus master mode this function can be used to write multiple registers of a slave. This function creates a Modbus function code 16 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Starting Address of the write.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterWriteMultipleRegistersResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

procedure TBrickletRS485.ModbusSlaveAnswerReadDiscreteInputsRequestLowLevel(const requestID: byte; const discreteInputsLength: word; const discreteInputsChunkOffset: word; const discreteInputsChunkData: array [0..471] of boolean)

In Modbus slave mode this function can be used to answer a master request to read discrete inputs.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Discrete Inputs: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the OnModbusSlaveReadDiscreteInputsRequest callback with the Request ID as provided by the argument of the callback.

function TBrickletRS485.ModbusMasterReadDiscreteInputs(const slaveAddress: byte; const startingAddress: longword; const count: word): byte

In Modbus master mode this function can be used to read discrete inputs from a slave. This function creates a Modbus function code 2 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Starting address of the read.
  • Count: Number of discrete inputs to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterReadDiscreteInputsResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

procedure TBrickletRS485.ModbusSlaveAnswerReadInputRegistersRequestLowLevel(const requestID: byte; const inputRegistersLength: word; const inputRegistersChunkOffset: word; const inputRegistersChunkData: array [0..28] of word)

In Modbus slave mode this function can be used to answer a master request to read input registers.

  • Request ID: Request ID of the corresponding request that is being answered.
  • Input Registers: Data that is to be sent to the Modbus master for the corresponding request.

This function must be called from the OnModbusSlaveReadInputRegistersRequest callback with the Request ID as provided by the argument of the callback.

function TBrickletRS485.ModbusMasterReadInputRegisters(const slaveAddress: byte; const startingAddress: longword; const count: word): byte

In Modbus master mode this function can be used to read input registers from a slave. This function creates a Modbus function code 4 request.

  • Slave Address: Address of the target Modbus slave.
  • Starting Address: Starting address of the read.
  • Count: Number of input registers to read.

Upon success the function will return a non-zero request ID which will represent the current request initiated by the Modbus master. In case of failure the returned request ID will be 0.

When successful this function will also invoke the OnModbusMasterReadInputRegistersResponse callback. In this callback the Request ID provided by the callback argument must be matched with the Request ID returned from this function to verify that the callback is indeed for a particular request.

function TBrickletRS485.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 TBrickletRS485.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 TBrickletRS485.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_RS485_FUNCTION_ENABLE_READ_CALLBACK = 3
  • BRICKLET_RS485_FUNCTION_DISABLE_READ_CALLBACK = 4
  • BRICKLET_RS485_FUNCTION_SET_RS485_CONFIGURATION = 6
  • BRICKLET_RS485_FUNCTION_SET_MODBUS_CONFIGURATION = 8
  • BRICKLET_RS485_FUNCTION_SET_MODE = 10
  • BRICKLET_RS485_FUNCTION_SET_COMMUNICATION_LED_CONFIG = 12
  • BRICKLET_RS485_FUNCTION_SET_ERROR_LED_CONFIG = 14
  • BRICKLET_RS485_FUNCTION_SET_BUFFER_CONFIG = 16
  • BRICKLET_RS485_FUNCTION_ENABLE_ERROR_COUNT_CALLBACK = 19
  • BRICKLET_RS485_FUNCTION_DISABLE_ERROR_COUNT_CALLBACK = 20
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_REPORT_EXCEPTION = 24
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_COILS_REQUEST = 25
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_HOLDING_REGISTERS_REQUEST = 27
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_COIL_REQUEST = 29
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_REGISTER_REQUEST = 31
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_COILS_REQUEST = 33
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_REGISTERS_REQUEST = 35
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_DISCRETE_INPUTS_REQUEST = 37
  • BRICKLET_RS485_FUNCTION_MODBUS_SLAVE_ANSWER_READ_INPUT_REGISTERS_REQUEST = 39
  • BRICKLET_RS485_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BRICKLET_RS485_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BRICKLET_RS485_FUNCTION_RESET = 243
  • BRICKLET_RS485_FUNCTION_WRITE_UID = 248
procedure TBrickletRS485.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletRS485.GetSPITFPErrorCount(out errorCountAckChecksum: longword; out errorCountMessageChecksum: longword; out errorCountFrame: longword; out errorCountOverflow: longword)

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

function TBrickletRS485.SetBootloaderMode(const mode: byte): byte

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

  • BRICKLET_RS485_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICKLET_RS485_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICKLET_RS485_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICKLET_RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICKLET_RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BRICKLET_RS485_BOOTLOADER_STATUS_OK = 0
  • BRICKLET_RS485_BOOTLOADER_STATUS_INVALID_MODE = 1
  • BRICKLET_RS485_BOOTLOADER_STATUS_NO_CHANGE = 2
  • BRICKLET_RS485_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BRICKLET_RS485_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BRICKLET_RS485_BOOTLOADER_STATUS_CRC_MISMATCH = 5
function TBrickletRS485.GetBootloaderMode: byte

Returns the current bootloader mode, see SetBootloaderMode.

The following constants are available for this function:

  • BRICKLET_RS485_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICKLET_RS485_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICKLET_RS485_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICKLET_RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICKLET_RS485_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
procedure TBrickletRS485.SetWriteFirmwarePointer(const pointer: longword)

Sets the firmware pointer for WriteFirmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

function TBrickletRS485.WriteFirmware(const data: array [0..63] of byte): byte

Writes 64 Bytes of firmware at the position as written by SetWriteFirmwarePointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

procedure TBrickletRS485.SetStatusLEDConfig(const config: byte)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

  • BRICKLET_RS485_STATUS_LED_CONFIG_OFF = 0
  • BRICKLET_RS485_STATUS_LED_CONFIG_ON = 1
  • BRICKLET_RS485_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_RS485_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickletRS485.GetStatusLEDConfig: byte

Returns the configuration as set by SetStatusLEDConfig

The following constants are available for this function:

  • BRICKLET_RS485_STATUS_LED_CONFIG_OFF = 0
  • BRICKLET_RS485_STATUS_LED_CONFIG_ON = 1
  • BRICKLET_RS485_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_RS485_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickletRS485.GetChipTemperature: smallint

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

procedure TBrickletRS485.Reset

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

procedure TBrickletRS485.WriteUID(const uid: longword)

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

function TBrickletRS485.ReadUID: longword

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

procedure TBrickletRS485.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

procedure TBrickletRS485.EnableReadCallback

Enables the OnRead callback.

By default the callback is disabled.

procedure TBrickletRS485.DisableReadCallback

Disables the OnRead callback.

By default the callback is disabled.

function TBrickletRS485.IsReadCallbackEnabled: boolean

Returns true if the OnRead callback is enabled, false otherwise.

procedure TBrickletRS485.EnableErrorCountCallback

Enables the OnErrorCount callback.

By default the callback is disabled.

procedure TBrickletRS485.DisableErrorCountCallback

Disables the OnErrorCount callback.

By default the callback is disabled.

function TBrickletRS485.IsErrorCountCallbackEnabled: boolean

Returns true if the OnErrorCount callback is enabled, false otherwise.

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: TBrickletRS485; const param: word);
begin
  WriteLn(param);
end;

rs485.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 TBrickletRS485.OnReadLowLevel
procedure(sender: TBrickletRS485; const messageLength: word; const messageChunkOffset: word; const messageChunkData: array [0..59] of char) of object;

This callback is called if new data is available.

To enable this callback, use EnableReadCallback.

property TBrickletRS485.OnErrorCount
procedure(sender: TBrickletRS485; const overrunErrorCount: longword; const parityErrorCount: longword) of object;

This callback is called if a new error occurs. It returns the current overrun and parity error count.

property TBrickletRS485.OnModbusSlaveReadCoilsRequest
procedure(sender: TBrickletRS485; const requestID: byte; const startingAddress: longword; const count: word) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read coils. The parameters are request ID of the request, the starting address and the number of coils to be read as received by the request.

To send a response of this request use ModbusSlaveAnswerReadCoilsRequest.

property TBrickletRS485.OnModbusMasterReadCoilsResponseLowLevel
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint; const coilsLength: word; const coilsChunkOffset: word; const coilsChunkData: array [0..463] of boolean) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to read coils.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
property TBrickletRS485.OnModbusSlaveReadHoldingRegistersRequest
procedure(sender: TBrickletRS485; const requestID: byte; const startingAddress: longword; const count: word) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read holding registers. The parameters are request ID of the request, the starting address and the number of holding registers to be read as received by the request.

To send a response of this request use ModbusSlaveAnswerReadHoldingRegistersRequest.

property TBrickletRS485.OnModbusMasterReadHoldingRegistersResponseLowLevel
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint; const holdingRegistersLength: word; const holdingRegistersChunkOffset: word; const holdingRegistersChunkData: array [0..28] of word) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to read holding registers.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
property TBrickletRS485.OnModbusSlaveWriteSingleCoilRequest
procedure(sender: TBrickletRS485; const requestID: byte; const coilAddress: longword; const coilValue: boolean) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write a single coil. The parameters are request ID of the request, the coil address and the value of coil to be written as received by the request.

To send a response of this request use ModbusSlaveAnswerWriteSingleCoilRequest.

property TBrickletRS485.OnModbusMasterWriteSingleCoilResponse
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to write a single coil.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
property TBrickletRS485.OnModbusSlaveWriteSingleRegisterRequest
procedure(sender: TBrickletRS485; const requestID: byte; const registerAddress: longword; const registerValue: word) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write a single register. The parameters are request ID of the request, the register address and the register value to be written as received by the request.

To send a response of this request use ModbusSlaveAnswerWriteSingleRegisterRequest.

property TBrickletRS485.OnModbusMasterWriteSingleRegisterResponse
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to write a single register.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timed out or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
property TBrickletRS485.OnModbusSlaveWriteMultipleCoilsRequestLowLevel
procedure(sender: TBrickletRS485; const requestID: byte; const startingAddress: longword; const coilsLength: word; const coilsChunkOffset: word; const coilsChunkData: array [0..439] of boolean) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write multiple coils. The parameters are request ID of the request, the starting address and the data to be written as received by the request.

To send a response of this request use ModbusSlaveAnswerWriteMultipleCoilsRequest.

property TBrickletRS485.OnModbusMasterWriteMultipleCoilsResponse
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to read coils.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
property TBrickletRS485.OnModbusSlaveWriteMultipleRegistersRequestLowLevel
procedure(sender: TBrickletRS485; const requestID: byte; const startingAddress: longword; const registersLength: word; const registersChunkOffset: word; const registersChunkData: array [0..26] of word) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to write multiple registers. The parameters are request ID of the request, the starting address and the data to be written as received by the request.

To send a response of this request use ModbusSlaveAnswerWriteMultipleRegistersRequest.

property TBrickletRS485.OnModbusMasterWriteMultipleRegistersResponse
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to write multiple registers.

The parameters are request ID of the request and exception code of the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
property TBrickletRS485.OnModbusSlaveReadDiscreteInputsRequest
procedure(sender: TBrickletRS485; const requestID: byte; const startingAddress: longword; const count: word) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read discrete inputs. The parameters are request ID of the request, the starting address and the number of discrete inputs to be read as received by the request.

To send a response of this request use ModbusSlaveAnswerReadDiscreteInputsRequest.

property TBrickletRS485.OnModbusMasterReadDiscreteInputsResponseLowLevel
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint; const discreteInputsLength: word; const discreteInputsChunkOffset: word; const discreteInputsChunkData: array [0..463] of boolean) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to read discrete inputs.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
property TBrickletRS485.OnModbusSlaveReadInputRegistersRequest
procedure(sender: TBrickletRS485; const requestID: byte; const startingAddress: longword; const count: word) of object;

This callback is called only in Modbus slave mode when the slave receives a valid request from a Modbus master to read input registers. The parameters are request ID of the request, the starting address and the number of input registers to be read as received by the request.

To send a response of this request use ModbusSlaveAnswerReadInputRegistersRequest.

property TBrickletRS485.OnModbusMasterReadInputRegistersResponseLowLevel
procedure(sender: TBrickletRS485; const requestID: byte; const exceptionCode: shortint; const inputRegistersLength: word; const inputRegistersChunkOffset: word; const inputRegistersChunkData: array [0..28] of word) of object;

This callback is called only in Modbus master mode when the master receives a valid response of a request to read input registers.

The parameters are request ID of the request, exception code of the response and the data as received by the response.

Any non-zero exception code indicates a problem. If the exception code is greater than zero then the number represents a Modbus exception code. If it is less than zero then it represents other errors. For example, -1 indicates that the request timedout or that the master did not receive any valid response of the request within the master request timeout period as set by SetModbusConfiguration.

The following constants are available for this function:

  • BRICKLET_RS485_EXCEPTION_CODE_TIMEOUT = -1
  • BRICKLET_RS485_EXCEPTION_CODE_SUCCESS = 0
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BRICKLET_RS485_EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BRICKLET_RS485_EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BRICKLET_RS485_EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BRICKLET_RS485_EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BRICKLET_RS485_EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11

Constants

const BRICKLET_RS485_DEVICE_IDENTIFIER

This constant is used to identify a RS485 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_RS485_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a RS485 Bricklet.