Visual Basic .NET - RS485 Bricklet

This is the description of the Visual Basic .NET 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 Visual Basic .NET API bindings is part of their general description.

Examples

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

Loopback

Download (ExampleLoopback.vb)

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Imports System
Imports Tinkerforge

' 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

Module ExampleLoopback
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your RS485 Bricklet

    ' Callback subroutine for read callback
    Sub ReadCB(ByVal sender As BrickletRS485, ByVal message As Char())
        ' Assume that the message consists of ASCII characters and
        ' convert it from an array of chars to a string
        Console.WriteLine("Message: ""{0}""", New String(message))
    End Sub

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim rs485 As New BrickletRS485(UID, ipcon) ' Create device object

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

        ' Enable full-duplex mode
        rs485.SetRS485Configuration(115200, BrickletRS485.PARITY_NONE, _
                                    BrickletRS485.STOPBITS_1, _
                                    BrickletRS485.WORDLENGTH_8, _
                                    BrickletRS485.DUPLEX_FULL)

        ' Register read callback to subroutine ReadCB
        AddHandler rs485.ReadCallback, AddressOf ReadCB

        ' Enable read callback
        rs485.EnableReadCallback()

        ' Write "test" string
        rs485.write("test".ToCharArray())

        Console.WriteLine("Press key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

Modbus Master

Download (ExampleModbusMaster.vb)

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Imports System
Imports Tinkerforge

Module ExampleModbusMaster
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your RS485 Bricklet

    Dim expectedRequestID As Byte = 0

    ' Callback subroutine for Modbus master write single register response callback
    Sub ModbusMasterWriteSingleRegisterResponseCB(ByVal sender As BrickletRS485, _
                                                  ByVal requestID As Byte, _
                                                  ByVal exceptionCode As Short)
        Console.WriteLine("Request ID: " + requestID.ToString())
        Console.WriteLine("Exception Code: " + exceptionCode.ToString())

        If requestID <> expectedRequestID Then
            Console.WriteLine("Error: Unexpected request ID")
        End If
    End Sub

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim rs485 As New BrickletRS485(UID, ipcon) ' Create device object

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

        ' Set operating mode to Modbus RTU master
        rs485.SetMode(BrickletRS485.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 subroutine
        ' ModbusMasterWriteSingleRegisterResponseCB
        AddHandler rs485.ModbusMasterWriteSingleRegisterResponseCallback, _
                   AddressOf ModbusMasterWriteSingleRegisterResponseCB

        ' Write 65535 to register 42 of slave 17
        expectedRequestID = rs485.ModbusMasterWriteSingleRegister(17, 42, 65535)

        Console.WriteLine("Press key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

Modbus Slave

Download (ExampleModbusSlave.vb)

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Imports System
Imports Tinkerforge

Module ExampleModbusSlave
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your RS485 Bricklet

    ' Callback subroutine for Modbus slave write single register request callback
    Sub ModbusSlaveWriteSingleRegisterRequestCB(ByVal sender As BrickletRS485, _
                                                ByVal requestID As Byte, _
                                                ByVal registerAddress As Long, _
                                                ByVal registerValue As Integer)
        Console.WriteLine("Request ID: " + requestID.ToString())
        Console.WriteLine("Register Address: " + registerAddress.ToString())
        Console.WriteLine("Register Value: " + registerValue.ToString())

        If registerAddress <> 42 Then
            Console.WriteLine("Error: Invalid register address")
            sender.modbusSlaveReportException(requestID, BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS)
        Else
            sender.modbusSlaveAnswerWriteSingleRegisterRequest(requestID)
        End If
    End Sub

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim rs485 As New BrickletRS485(UID, ipcon) ' Create device object

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

        ' Set operating mode to Modbus RTU slave
        rs485.SetMode(BrickletRS485.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 subroutine
        ' ModbusSlaveWriteSingleRegisterRequestCB
        AddHandler rs485.ModbusSlaveWriteSingleRegisterRequestCallback, _
                   AddressOf ModbusSlaveWriteSingleRegisterRequestCB

        Console.WriteLine("Press key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

API

Since Visual Basic .NET does not support multiple return values directly, we use the ByRef keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

Basic Functions

Class BrickletRS485(ByVal uid As String, ByVal ipcon As IPConnection)

Creates an object with the unique device ID uid:

Dim rs485 As New BrickletRS485("YOUR_DEVICE_UID", ipcon)

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

Function BrickletRS485.Write(ByVal message() As Char) As Integer

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.

Function BrickletRS485.Read(ByVal length As Integer) As 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 ReadCallback callback.

Sub BrickletRS485.SetRS485Configuration(ByVal baudrate As Long, ByVal parity As Byte, ByVal stopbits As Byte, ByVal wordlength As Byte, ByVal duplex As 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:

  • BrickletRS485.PARITY_NONE = 0
  • BrickletRS485.PARITY_ODD = 1
  • BrickletRS485.PARITY_EVEN = 2
  • BrickletRS485.STOPBITS_1 = 1
  • BrickletRS485.STOPBITS_2 = 2
  • BrickletRS485.WORDLENGTH_5 = 5
  • BrickletRS485.WORDLENGTH_6 = 6
  • BrickletRS485.WORDLENGTH_7 = 7
  • BrickletRS485.WORDLENGTH_8 = 8
  • BrickletRS485.DUPLEX_HALF = 0
  • BrickletRS485.DUPLEX_FULL = 1
Sub BrickletRS485.GetRS485Configuration(ByRef baudrate As Long, ByRef parity As Byte, ByRef stopbits As Byte, ByRef wordlength As Byte, ByRef duplex As Byte)

Returns the configuration as set by SetRS485Configuration().

The following constants are available for this function:

  • BrickletRS485.PARITY_NONE = 0
  • BrickletRS485.PARITY_ODD = 1
  • BrickletRS485.PARITY_EVEN = 2
  • BrickletRS485.STOPBITS_1 = 1
  • BrickletRS485.STOPBITS_2 = 2
  • BrickletRS485.WORDLENGTH_5 = 5
  • BrickletRS485.WORDLENGTH_6 = 6
  • BrickletRS485.WORDLENGTH_7 = 7
  • BrickletRS485.WORDLENGTH_8 = 8
  • BrickletRS485.DUPLEX_HALF = 0
  • BrickletRS485.DUPLEX_FULL = 1
Sub BrickletRS485.SetModbusConfiguration(ByVal slaveAddress As Byte, ByVal masterRequestTimeout As Long)

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).

Sub BrickletRS485.GetModbusConfiguration(ByRef slaveAddress As Byte, ByRef masterRequestTimeout As Long)

Returns the configuration as set by SetModbusConfiguration().

Sub BrickletRS485.SetMode(ByVal mode As 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:

  • BrickletRS485.MODE_RS485 = 0
  • BrickletRS485.MODE_MODBUS_MASTER_RTU = 1
  • BrickletRS485.MODE_MODBUS_SLAVE_RTU = 2
Function BrickletRS485.GetMode() As Byte

Returns the configuration as set by SetMode().

The following constants are available for this function:

  • BrickletRS485.MODE_RS485 = 0
  • BrickletRS485.MODE_MODBUS_MASTER_RTU = 1
  • BrickletRS485.MODE_MODBUS_SLAVE_RTU = 2

Advanced Functions

Sub BrickletRS485.SetCommunicationLEDConfig(ByVal config As 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:

  • BrickletRS485.COMMUNICATION_LED_CONFIG_OFF = 0
  • BrickletRS485.COMMUNICATION_LED_CONFIG_ON = 1
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
Function BrickletRS485.GetCommunicationLEDConfig() As Byte

Returns the configuration as set by SetCommunicationLEDConfig()

The following constants are available for this function:

  • BrickletRS485.COMMUNICATION_LED_CONFIG_OFF = 0
  • BrickletRS485.COMMUNICATION_LED_CONFIG_ON = 1
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
Sub BrickletRS485.SetErrorLEDConfig(ByVal config As Byte)

Sets the error LED configuration.

By default the error LED turns on if there is any error (see ErrorCountCallback 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:

  • BrickletRS485.ERROR_LED_CONFIG_OFF = 0
  • BrickletRS485.ERROR_LED_CONFIG_ON = 1
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_ERROR = 3
Function BrickletRS485.GetErrorLEDConfig() As Byte

Returns the configuration as set by SetErrorLEDConfig().

The following constants are available for this function:

  • BrickletRS485.ERROR_LED_CONFIG_OFF = 0
  • BrickletRS485.ERROR_LED_CONFIG_ON = 1
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.ERROR_LED_CONFIG_SHOW_ERROR = 3
Sub BrickletRS485.SetBufferConfig(ByVal sendBufferSize As Integer, ByVal receiveBufferSize As Integer)

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 ReadCallback callback.

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

Sub BrickletRS485.GetBufferConfig(ByRef sendBufferSize As Integer, ByRef receiveBufferSize As Integer)

Returns the buffer configuration as set by SetBufferConfig().

Sub BrickletRS485.GetBufferStatus(ByRef sendBufferUsed As Integer, ByRef receiveBufferUsed As Integer)

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

See SetBufferConfig() for buffer size configuration.

Sub BrickletRS485.GetErrorCount(ByRef overrunErrorCount As Long, ByRef parityErrorCount As Long)

Returns the current number of overrun and parity errors.

Sub BrickletRS485.GetModbusCommonErrorCount(ByRef timeoutErrorCount As Long, ByRef checksumErrorCount As Long, ByRef frameTooBigErrorCount As Long, ByRef illegalFunctionErrorCount As Long, ByRef illegalDataAddressErrorCount As Long, ByRef illegalDataValueErrorCount As Long, ByRef slaveDeviceFailureErrorCount As Long)

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.
Sub BrickletRS485.ModbusSlaveReportException(ByVal requestID As Byte, ByVal exceptionCode As Short)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Sub BrickletRS485.ModbusSlaveAnswerReadCoilsRequest(ByVal requestID As Byte, ByVal coils() As 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 ModbusSlaveReadCoilsRequestCallback callback with the Request ID as provided by the argument of the callback.

Function BrickletRS485.ModbusMasterReadCoils(ByVal slaveAddress As Byte, ByVal startingAddress As Long, ByVal count As Integer) As 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 ModbusMasterReadCoilsResponseCallback 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.

Sub BrickletRS485.ModbusSlaveAnswerReadHoldingRegistersRequest(ByVal requestID As Byte, ByVal holdingRegisters() As Integer)

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 ModbusSlaveReadHoldingRegistersRequestCallback callback with the Request ID as provided by the argument of the callback.

Function BrickletRS485.ModbusMasterReadHoldingRegisters(ByVal slaveAddress As Byte, ByVal startingAddress As Long, ByVal count As Integer) As 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 ModbusMasterReadHoldingRegistersResponseCallback 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.

Sub BrickletRS485.ModbusSlaveAnswerWriteSingleCoilRequest(ByVal requestID As 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 ModbusSlaveWriteSingleCoilRequestCallback callback with the Request ID as provided by the arguments of the callback.

Function BrickletRS485.ModbusMasterWriteSingleCoil(ByVal slaveAddress As Byte, ByVal coilAddress As Long, ByVal coilValue As Boolean) As 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 ModbusMasterWriteSingleCoilResponseCallback 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.

Sub BrickletRS485.ModbusSlaveAnswerWriteSingleRegisterRequest(ByVal requestID As 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 ModbusSlaveWriteSingleRegisterRequestCallback callback with the Request ID, Register Address and Register Value as provided by the arguments of the callback.

Function BrickletRS485.ModbusMasterWriteSingleRegister(ByVal slaveAddress As Byte, ByVal registerAddress As Long, ByVal registerValue As Integer) As 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 ModbusMasterWriteSingleRegisterResponseCallback 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.

Sub BrickletRS485.ModbusSlaveAnswerWriteMultipleCoilsRequest(ByVal requestID As 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 ModbusSlaveWriteMultipleCoilsRequestCallback callback with the Request ID of the callback.

Function BrickletRS485.ModbusMasterWriteMultipleCoils(ByVal slaveAddress As Byte, ByVal startingAddress As Long, ByVal coils() As Boolean) As 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 ModbusMasterWriteMultipleCoilsResponseCallback 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.

Sub BrickletRS485.ModbusSlaveAnswerWriteMultipleRegistersRequest(ByVal requestID As 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 ModbusSlaveWriteMultipleRegistersRequestCallback callback with the Request ID of the callback.

Function BrickletRS485.ModbusMasterWriteMultipleRegisters(ByVal slaveAddress As Byte, ByVal startingAddress As Long, ByVal registers() As Integer) As 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 ModbusMasterWriteMultipleRegistersResponseCallback 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.

Sub BrickletRS485.ModbusSlaveAnswerReadDiscreteInputsRequest(ByVal requestID As Byte, ByVal discreteInputs() As 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 ModbusSlaveReadDiscreteInputsRequestCallback callback with the Request ID as provided by the argument of the callback.

Function BrickletRS485.ModbusMasterReadDiscreteInputs(ByVal slaveAddress As Byte, ByVal startingAddress As Long, ByVal count As Integer) As 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 ModbusMasterReadDiscreteInputsResponseCallback 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.

Sub BrickletRS485.ModbusSlaveAnswerReadInputRegistersRequest(ByVal requestID As Byte, ByVal inputRegisters() As Integer)

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 ModbusSlaveReadInputRegistersRequestCallback callback with the Request ID as provided by the argument of the callback.

Function BrickletRS485.ModbusMasterReadInputRegisters(ByVal slaveAddress As Byte, ByVal startingAddress As Long, ByVal count As Integer) As 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 ModbusMasterReadInputRegistersResponseCallback 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 BrickletRS485.GetAPIVersion() As 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 BrickletRS485.GetResponseExpected(ByVal functionId As Byte) As 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.

Sub BrickletRS485.SetResponseExpected(ByVal functionId As Byte, ByVal responseExpected As 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:

  • BrickletRS485.FUNCTION_ENABLE_READ_CALLBACK = 3
  • BrickletRS485.FUNCTION_DISABLE_READ_CALLBACK = 4
  • BrickletRS485.FUNCTION_SET_RS485_CONFIGURATION = 6
  • BrickletRS485.FUNCTION_SET_MODBUS_CONFIGURATION = 8
  • BrickletRS485.FUNCTION_SET_MODE = 10
  • BrickletRS485.FUNCTION_SET_COMMUNICATION_LED_CONFIG = 12
  • BrickletRS485.FUNCTION_SET_ERROR_LED_CONFIG = 14
  • BrickletRS485.FUNCTION_SET_BUFFER_CONFIG = 16
  • BrickletRS485.FUNCTION_ENABLE_ERROR_COUNT_CALLBACK = 19
  • BrickletRS485.FUNCTION_DISABLE_ERROR_COUNT_CALLBACK = 20
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_REPORT_EXCEPTION = 24
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_COILS_REQUEST = 25
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_HOLDING_REGISTERS_REQUEST = 27
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_COIL_REQUEST = 29
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_SINGLE_REGISTER_REQUEST = 31
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_COILS_REQUEST = 33
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_WRITE_MULTIPLE_REGISTERS_REQUEST = 35
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_DISCRETE_INPUTS_REQUEST = 37
  • BrickletRS485.FUNCTION_MODBUS_SLAVE_ANSWER_READ_INPUT_REGISTERS_REQUEST = 39
  • BrickletRS485.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletRS485.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletRS485.FUNCTION_RESET = 243
  • BrickletRS485.FUNCTION_WRITE_UID = 248
Sub BrickletRS485.SetResponseExpectedAll(ByVal responseExpected As Boolean)

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

Sub BrickletRS485.GetSPITFPErrorCount(ByRef errorCountAckChecksum As Long, ByRef errorCountMessageChecksum As Long, ByRef errorCountFrame As Long, ByRef errorCountOverflow As Long)

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 BrickletRS485.SetBootloaderMode(ByVal mode As Byte) As 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:

  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BrickletRS485.BOOTLOADER_STATUS_OK = 0
  • BrickletRS485.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletRS485.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletRS485.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletRS485.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletRS485.BOOTLOADER_STATUS_CRC_MISMATCH = 5
Function BrickletRS485.GetBootloaderMode() As Byte

Returns the current bootloader mode, see SetBootloaderMode().

The following constants are available for this function:

  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletRS485.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletRS485.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
Sub BrickletRS485.SetWriteFirmwarePointer(ByVal pointer As Long)

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 BrickletRS485.WriteFirmware(ByVal data() As Byte) As 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.

Sub BrickletRS485.SetStatusLEDConfig(ByVal config As 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:

  • BrickletRS485.STATUS_LED_CONFIG_OFF = 0
  • BrickletRS485.STATUS_LED_CONFIG_ON = 1
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_STATUS = 3
Function BrickletRS485.GetStatusLEDConfig() As Byte

Returns the configuration as set by SetStatusLEDConfig()

The following constants are available for this function:

  • BrickletRS485.STATUS_LED_CONFIG_OFF = 0
  • BrickletRS485.STATUS_LED_CONFIG_ON = 1
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletRS485.STATUS_LED_CONFIG_SHOW_STATUS = 3
Function BrickletRS485.GetChipTemperature() As Short

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.

Sub BrickletRS485.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!

Sub BrickletRS485.WriteUID(ByVal uid As Long)

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 BrickletRS485.ReadUID() As Long

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

Sub BrickletRS485.GetIdentity(ByRef uid As String, ByRef connectedUid As String, ByRef position As Char, ByRef hardwareVersion() As Byte, ByRef firmwareVersion() As Byte, ByRef deviceIdentifier As Integer)

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

Sub BrickletRS485.EnableReadCallback()

Enables the ReadCallback callback.

By default the callback is disabled.

Sub BrickletRS485.DisableReadCallback()

Disables the ReadCallback callback.

By default the callback is disabled.

Function BrickletRS485.IsReadCallbackEnabled() As Boolean

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

Sub BrickletRS485.EnableErrorCountCallback()

Enables the ErrorCountCallback callback.

By default the callback is disabled.

Sub BrickletRS485.DisableErrorCountCallback()

Disables the ErrorCountCallback callback.

By default the callback is disabled.

Function BrickletRS485.IsErrorCountCallbackEnabled() As Boolean

Returns true if the ErrorCountCallback 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:

Sub MyCallback(ByVal sender As BrickletRS485, ByVal value As Short)
    Console.WriteLine("Value: {0}", value)
End Sub

AddHandler rs485.ExampleCallback, AddressOf 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.

Event BrickletRS485.ReadCallback(ByVal sender As BrickletRS485, ByVal message() As Char)

This callback is called if new data is available.

To enable this callback, use EnableReadCallback().

Event BrickletRS485.ErrorCountCallback(ByVal sender As BrickletRS485, ByVal overrunErrorCount As Long, ByVal parityErrorCount As Long)

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

Event BrickletRS485.ModbusSlaveReadCoilsRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal startingAddress As Long, ByVal count As Integer)

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().

Event BrickletRS485.ModbusMasterReadCoilsResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short, ByVal coils() As Boolean)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Event BrickletRS485.ModbusSlaveReadHoldingRegistersRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal startingAddress As Long, ByVal count As Integer)

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().

Event BrickletRS485.ModbusMasterReadHoldingRegistersResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short, ByVal holdingRegisters() As Integer)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Event BrickletRS485.ModbusSlaveWriteSingleCoilRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal coilAddress As Long, ByVal coilValue As Boolean)

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().

Event BrickletRS485.ModbusMasterWriteSingleCoilResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Event BrickletRS485.ModbusSlaveWriteSingleRegisterRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal registerAddress As Long, ByVal registerValue As Integer)

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().

Event BrickletRS485.ModbusMasterWriteSingleRegisterResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Event BrickletRS485.ModbusSlaveWriteMultipleCoilsRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal startingAddress As Long, ByVal coils() As Boolean)

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().

Event BrickletRS485.ModbusMasterWriteMultipleCoilsResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Event BrickletRS485.ModbusSlaveWriteMultipleRegistersRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal startingAddress As Long, ByVal registers() As Integer)

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().

Event BrickletRS485.ModbusMasterWriteMultipleRegistersResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Event BrickletRS485.ModbusSlaveReadDiscreteInputsRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal startingAddress As Long, ByVal count As Integer)

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().

Event BrickletRS485.ModbusMasterReadDiscreteInputsResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short, ByVal discreteInputs() As Boolean)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11
Event BrickletRS485.ModbusSlaveReadInputRegistersRequestCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal startingAddress As Long, ByVal count As Integer)

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().

Event BrickletRS485.ModbusMasterReadInputRegistersResponseCallback(ByVal sender As BrickletRS485, ByVal requestID As Byte, ByVal exceptionCode As Short, ByVal inputRegisters() As Integer)

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:

  • BrickletRS485.EXCEPTION_CODE_TIMEOUT = -1
  • BrickletRS485.EXCEPTION_CODE_SUCCESS = 0
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_FUNCTION = 1
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_ADDRESS = 2
  • BrickletRS485.EXCEPTION_CODE_ILLEGAL_DATA_VALUE = 3
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_FAILURE = 4
  • BrickletRS485.EXCEPTION_CODE_ACKNOWLEDGE = 5
  • BrickletRS485.EXCEPTION_CODE_SLAVE_DEVICE_BUSY = 6
  • BrickletRS485.EXCEPTION_CODE_MEMORY_PARITY_ERROR = 8
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_PATH_UNAVAILABLE = 10
  • BrickletRS485.EXCEPTION_CODE_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND = 11

Constants

Const BrickletRS485.DEVICE_IDENTIFIER

This constant is used to identify a RS485 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.

Const BrickletRS485.DEVICE_DISPLAY_NAME

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