NModbus

A simple implementation of the point source. All registers are

Collection of discrete values.

Number of bits per byte.

Initializes a new instance of the class.

Initializes a new instance of the class.

Array for discrete collection.

Initializes a new instance of the class.

Array for discrete collection.

Initializes a new instance of the class.

List for discrete collection.

Initializes a new instance of the class.

List for discrete collection.

Gets the network bytes.

Gets the byte count.

Returns a that represents the current .

A that represents the current .

The Extended Memory file number

The starting register address within the file.

The bytes written to the extended memory file.

Gets the byte count.

Returns a that represents the current .

A that represents the current .

Modbus message containing data.

Gets the network bytes.

Gets the byte count.

A simple implementation of the point source. Memory for all points is allocated the first time a point is accessed. This is useful for cases where many points are used.

Collection of 16 bit registers.

Initializes a new instance of the class.

Initializes a new instance of the class.

Array for register collection.

Initializes a new instance of the class.

Array for register collection.

Initializes a new instance of the class.

List for register collection.

Gets the byte count.

Returns a that represents the current .

A that represents the current .

Provides concurrency control across multiple Modbus readers/writers.

Modbus device.

Gets the Modbus Transport.

Releases unmanaged and - optionally - managed resources.

Releases unmanaged and - optionally - managed resources.

true to release both managed and unmanaged resources; false to release only unmanaged resources.

Base class for

The type of request to handle.

Modbus IP master device.

Modbus IP master device.

Transport used by this master.

Reads from 1 to 2000 contiguous coils status.

Address to begin reading. Number of coils to read. Coils status.

Asynchronously reads from 1 to 2000 contiguous coils status.

Address to begin reading. Number of coils to read. A task that represents the asynchronous read operation.

Reads from 1 to 2000 contiguous discrete input status.

Address to begin reading. Number of discrete inputs to read. Discrete inputs status.

Asynchronously reads from 1 to 2000 contiguous discrete input status.

Address to begin reading. Number of discrete inputs to read. A task that represents the asynchronous read operation.

Reads contiguous block of holding registers.

Address to begin reading. Number of holding registers to read. Holding registers status.

Asynchronously reads contiguous block of holding registers.

Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Reads contiguous block of input registers.

Address to begin reading. Number of holding registers to read. Input registers status.

Asynchronously reads contiguous block of input registers.

Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Writes a single coil value.

Address to write value to. Value to write.

Asynchronously writes a single coil value.

Address to write value to. Value to write. A task that represents the asynchronous write operation.

Write a single holding register.

Address to write. Value to write.

Asynchronously writes a single holding register.

Address to write. Value to write. A task that represents the asynchronous write operation.

Write a block of 1 to 123 contiguous registers.

Address to begin writing values. Values to write.

Asynchronously writes a block of 1 to 123 contiguous registers.

Address to begin writing values. Values to write. A task that represents the asynchronous write operation.

Force each coil in a sequence of coils to a provided value.

Address to begin writing values. Values to write.

Asynchronously writes a sequence of coils.

Address to begin writing values. Values to write. A task that represents the asynchronous write operation

Performs a combination of one read operation and one write operation in a single MODBUS transaction. The write operation is performed before the read. Message uses default TCP slave id of 0.

Address to begin reading (Holding registers are addressed starting at 0). Number of registers to read. Address to begin writing (Holding registers are addressed starting at 0). Register values to write.

Asynchronously performs a combination of one read operation and one write operation in a single Modbus transaction. The write operation is performed before the read.

Address to begin reading (Holding registers are addressed starting at 0). Number of registers to read. Address to begin writing (Holding registers are addressed starting at 0). Register values to write. A task that represents the asynchronous operation.

Modbus master device.

Reads from 1 to 2000 contiguous coils status.

Address of device to read values from. Address to begin reading. Number of coils to read. Coils status.

Asynchronously reads from 1 to 2000 contiguous coils status.

Address of device to read values from. Address to begin reading. Number of coils to read. A task that represents the asynchronous read operation.

Reads from 1 to 2000 contiguous discrete input status.

Address of device to read values from. Address to begin reading. Number of discrete inputs to read. Discrete inputs status.

Asynchronously reads from 1 to 2000 contiguous discrete input status.

Address of device to read values from. Address to begin reading. Number of discrete inputs to read. A task that represents the asynchronous read operation.

Reads contiguous block of holding registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. Holding registers status.

Asynchronously reads contiguous block of holding registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Reads contiguous block of input registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. Input registers status.

Asynchronously reads contiguous block of input registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Writes a single coil value.

Address of the device to write to. Address to write value to. Value to write.

Asynchronously writes a single coil value.

Address of the device to write to. Address to write value to. Value to write. A task that represents the asynchronous write operation.

Writes a single holding register.

Address of the device to write to. Address to write. Value to write.

Asynchronously writes a single holding register.

Address of the device to write to. Address to write. Value to write. A task that represents the asynchronous write operation.

Write a block of 1 to 123 contiguous 16 bit holding registers.

Address of the device to write to. Address to begin writing values. Values to write.

Asynchronously writes a block of 1 to 123 contiguous registers.

Address of the device to write to. Address to begin writing values. Values to write. A task that represents the asynchronous write operation.

Writes a sequence of coils.

Address of the device to write to. Address to begin writing values. Values to write.

Asynchronously writes a sequence of coils.

Address of the device to write to. Address to begin writing values. Values to write. A task that represents the asynchronous write operation.

Performs a combination of one read operation and one write operation in a single Modbus transaction. The write operation is performed before the read.

Address of device to read values from. Address to begin reading (Holding registers are addressed starting at 0). Number of registers to read. Address to begin writing (Holding registers are addressed starting at 0). Register values to write.

Asynchronously performs a combination of one read operation and one write operation in a single Modbus transaction. The write operation is performed before the read.

Address of device to read values from. Address to begin reading (Holding registers are addressed starting at 0). Number of registers to read. Address to begin writing (Holding registers are addressed starting at 0). Register values to write. A task that represents the asynchronous operation.

Write a file record to the device.

Address of device to write values to The Extended Memory file number The starting register address within the file The data to be written

Executes the custom message.

The type of the response. The request.

Represents an incoming connection from a Modbus master. Contains the slave's logic to process the connection.

Occurs when a Modbus master TCP connection is closed.

Modbus serial master device.

Gets the Modbus Transport.

Serial Line only. Diagnostic function which loops back the original data. NModbus only supports looping back one ushort value, this is a limitation of the "Best Effort" implementation of the RTU protocol.

Address of device to test. Data to return. Return true if slave device echoed data.

Start slave listening for requests.

Apply the request.

Modbus TCP slave device.

Gets the Modbus TCP Masters connected to this Modbus TCP Slave.

Gets the server.

The server. This property is not thread safe, it should only be consumed within a lock.

Start slave listening for requests.

Releases unmanaged and - optionally - managed resources

true to release both managed and unmanaged resources; false to release only unmanaged resources. Dispose is thread-safe.

Modbus UDP slave device.

Start slave listening for requests.

Modbus Slave request event args containing information on the message.

Determines whether the crc stored in the message matches the calculated crc.

Gets the CRC of the message

Gets the specified value in the dictionary. If not found, returns default for TValue.

Utility extensions for the Enron Modbus dialect.

Reads contiguous block of input registers with 32 bit register size.

The Modbus master. Address of device to read values from. Address to begin reading. Number of holding registers to read. Input registers status.

Reads contiguous block of holding registers.

The Modbus master. Address of device to read values from. Address to begin reading. Number of holding registers to read. Holding registers status.

Asynchronously reads contiguous block of input registers with 32 bit register size.

The Modbus master. Address of device to read values from. Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Asynchronously reads contiguous block of holding registers.

The Modbus master. Address of device to read values from. Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Write a single 16 bit holding register.

The Modbus master. Address of the device to write to. Address to write. Value to write.

Write a block of contiguous 32 bit holding registers.

The Modbus master. Address of the device to write to. Address to begin writing values. Values to write.

Convert the 32 bit registers to two 16 bit values.

Convert the double 16 bit registers to single 32 bit values.

Class containing functions to covert endian from network device to host this code is running on.

Converts BigEndian source bytes to Endian format of system. Source BE: 0x0A,0x0B,0x0C,0x0D. Target BE: 0x0A,0x0B,0x0C,0x0D. Target LE: 0x0D,0x0C,0x0B,0x0A.

Byte array from device Bytes in Endian format for system

Converts LittleEndian source bytes to Endian format of system. Source LE: 0x0D,0x0C,0x0B,0x0A. Target BE: 0x0A,0x0B,0x0C,0x0D. Target LE: 0x0D,0x0C,0x0B,0x0A.

Byte array from device Bytes in Endian format for system

This class provides some functions that can be used to read/write values of a set word size.

Utility Class to support Modbus 32/64bit devices.

Constructor with values to be used by all methods. Default is 32bit, LittleEndian, with wordswapping.

The Modbus master Wordsize used by device. 16/32/64 are valid. The endian encoding of the device. Should the ushort words mirrored then flattened to bytes.

Reads registers and converts the result into a char array.

Address of device to read values from. Address to begin reading. Number of chars to read.

Reads registers and converts the result into a ushort array.

Address of device to read values from. Address to begin reading. Number of ushorts to read.

Reads registers and converts the result into a short array.

Address of device to read values from. Address to begin reading. Number of shots to read.

Reads registers and converts the result into a uint array.

Address of device to read values from. Address to begin reading. Number of uints to read.

Reads registers and converts the result into a int array.

Address of device to read values from. Address to begin reading. Number of ints to read.

Reads registers and converts the result into a float array.

Address of device to read values from. Address to begin reading. Number of floats to read.

Write a char array to registers.

Address of the device to write to. Address to start writting values at. Chars to write to device.

Write a ushort array to registers.

Address of the device to write to. Address to start writting values at. Ushorts to write to device.

Write a short array to registers.

Address of the device to write to. Address to start writting values at. Shorts to write to device.

Write a int array to registers.

Address of the device to write to. Address to start writting values at. Ints to write to device.

Write a uint array to registers.

Address of the device to write to. Address to start writting values at. Uints to write to device.

Write a float array to registers.

Address of the device to write to. Address to start writting values at. Floats to write to device.

Extension methods for the IModbusFactory interface.

Creates an RTU master.

Creates an ASCII master.

Creates a TCP or UDP master.

Creates an RTU slave network.

Creates an ASCII slave network.

Container for modbus function services.

Get the service for a given function code.

Gets all of the services.

Create an rtu master.

Create a TCP master.

Creates a Modbus Slave.

The address of this slave on the Modbus network. Optionally specify a custom data store for the created slave.

Creates a slave network based on the RTU transport.

Creates an ascii slave network.

The ascii transport to base this on.

Create a slave network based on TCP.

Creates a UDP modbus slave network.

Creates an RTU transpoort.

Creates an Ascii Transport.

Creates an IP Transport

A Modbus slave message handler.

The function code that this handles

Creates a message that wrapps the request frame.

Handle a slave request.

Gets the number of bytes to read for a request

Gets the number of bytes to read for a response.

Simple logging target. Designed to be easily integrated into other logging frameworks.

Conditionally log a message

True if this level should be logged, false otherwise.

Modbus master device.

Transport used by this master.

Reads from 1 to 2000 contiguous coils status.

Address of device to read values from. Address to begin reading. Number of coils to read. Coils status.

Asynchronously reads from 1 to 2000 contiguous coils status.

Address of device to read values from. Address to begin reading. Number of coils to read. A task that represents the asynchronous read operation.

Reads from 1 to 2000 contiguous discrete input status.

Address of device to read values from. Address to begin reading. Number of discrete inputs to read. Discrete inputs status.

Asynchronously reads from 1 to 2000 contiguous discrete input status.

Address of device to read values from. Address to begin reading. Number of discrete inputs to read. A task that represents the asynchronous read operation.

Reads contiguous block of holding registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. Holding registers status.

Asynchronously reads contiguous block of holding registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Reads contiguous block of input registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. Input registers status.

Asynchronously reads contiguous block of input registers.

Address of device to read values from. Address to begin reading. Number of holding registers to read. A task that represents the asynchronous read operation.

Writes a single coil value.

Address of the device to write to. Address to write value to. Value to write.

Asynchronously writes a single coil value.

Address of the device to write to. Address to write value to. Value to write. A task that represents the asynchronous write operation.

Writes a single holding register.

Address of the device to write to. Address to write. Value to write.

Asynchronously writes a single holding register.

Address of the device to write to. Address to write. Value to write. A task that represents the asynchronous write operation.

Writes a block of 1 to 123 contiguous registers.

Address of the device to write to. Address to begin writing values. Values to write.

Asynchronously writes a block of 1 to 123 contiguous registers.

Address of the device to write to. Address to begin writing values. Values to write. A task that represents the asynchronous write operation.

Writes a sequence of coils.

Address of the device to write to. Address to begin writing values. Values to write.

Asynchronously writes a sequence of coils.

Address of the device to write to. Address to begin writing values. Values to write. A task that represents the asynchronous write operation.

Performs a combination of one read operation and one write operation in a single Modbus transaction. The write operation is performed before the read.

Address of device to read values from. Address to begin reading (Holding registers are addressed starting at 0). Number of registers to read. Address to begin writing (Holding registers are addressed starting at 0). Register values to write.

Asynchronously performs a combination of one read operation and one write operation in a single Modbus transaction. The write operation is performed before the read.

Address of device to read values from. Address to begin reading (Holding registers are addressed starting at 0). Number of registers to read. Address to begin writing (Holding registers are addressed starting at 0). Register values to write. A task that represents the asynchronous operation

Write a file record to the device.

Address of device to write values to The Extended Memory file number The starting register address within the file The data to be written

Executes the custom message.

The type of the response. The request.

A message built by the master (client) that initiates a Modbus transaction.

The function code tells the server what kind of action to perform.

Address of the slave (server).

Composition of the slave address and protocol data unit.

Composition of the function code and message data.

A unique identifier assigned to a message when using the IP protocol.

Initializes a modbus message from the specified message frame.

Bytes of Modbus frame.

Modbus Serial Master device.

Transport for used by this master.

Serial Line only. Diagnostic function which loops back the original data. NModbus only supports looping back one ushort value, this is a limitation of the "Best Effort" implementation of the RTU protocol.

Address of device to test. Data to return. Return true if slave device echoed data.

A modbus slave.

Gets the unit id of this slave.

Gets the data store for this slave.

Applies the request.

A network of slave devices on a single transport.

Listen for incoming requests.

Add a slave to the network.

Get a slave from the network.

The slave address The specified slave, or null if one can't be found.

Removes a slave from the network.

Modbus TCP slave device.

Gets the Modbus TCP Masters connected to this Modbus TCP Slave.

Represents a memory map.

Read a series of points.

Write a series of points.

Object simulation of a device memory map.

Gets the descrete coils.

Gets the discrete inputs.

Gets the holding registers.

Gets the input registers.

Following the guidelines from https://github.com/aspnet/Logging/wiki/Guidelines.

The most detailed log messages, may contain sensitive application data. These messages should be disabled by default and should never be enabled in a production environment.

Logs that are used for interactive investigation during development should use the Debug level. These logs should primarily contain information useful for debugging and have no long-term value. This is the default most verbose level of logging.

Track the general flow of the application using logs at the Information level. These logs should have value in the long term.

Warnings should highlight an abnormal or unexpected event in the application flow. This event does not cause the application execution to stop, but can signify sub-optimal performance or a potential problem for the future. A common place to log a warning is from handled exceptions.

An error should be logged when the current flow of execution is stopped due to a failure. These should indicate a failure in the current activity, not an application-wide failure. These will mainly be unhandled exceptions and recoverable failures.

A critical log should describe an unrecoverable application or system crash, or a catastrophic failure that requires immediate attention.

An exception that provides the exception code that will be sent in response to an invalid Modbus request.

Initializes a new instance of the class with a specified Modbus exception code.

The Modbus exception code to provide to the slave.

Initializes a new instance of the class with a specified error message and Modbus exception code.

The error message that explains the reason for the exception. The Modbus exception code to provide to the slave.

Initializes a new instance of the class with a specified Modbus exception code and a reference to the inner exception that is the cause of this exception.

The Modbus exception code to provide to the slave. The exception that is the cause of the current exception. If the parameter is not a null reference, the current exception is raised in a catch block that handles the inner exception.

Initializes a new instance of the class with a specified Modbus exception code and a reference to the inner exception that is the cause of this exception.

The error message that explains the reason for the exception. The Modbus exception code to provide to the slave. The exception that is the cause of the current exception. If the parameter is not a null reference, the current exception is raised in a catch block that handles the inner exception.

Initializes a new instance of the class with serialized data.

The object that holds the serialized object data. The contextual information about the source or destination.

Gets the Modbus exception code to provide to the slave.

Sets the object with the Modbus exception code and additional exception information.

The that holds the serialized object data about the exception being thrown. The that contains contextual information about the source or destination.

Represents a serial resource. Implementor - http://en.wikipedia.org/wiki/Bridge_Pattern

Indicates that no timeout should occur.

Gets or sets the number of milliseconds before a timeout occurs when a read operation does not finish.

Gets or sets the number of milliseconds before a timeout occurs when a write operation does not finish.

Purges the receive buffer.

Reads a number of bytes from the input buffer and writes those bytes into a byte array at the specified offset.

The byte array to write the input to. The offset in the buffer array to begin writing. The number of bytes to read. The number of bytes read.

Writes a specified number of bytes to the port from an output buffer, starting at the specified offset.

The byte array that contains the data to write to the port. The offset in the buffer array to begin writing. The number of bytes to write.

Refined Abstraction - http://en.wikipedia.org/wiki/Bridge_Pattern

Transport for Internet protocols. Refined Abstraction - http://en.wikipedia.org/wiki/Bridge_Pattern

Create a new transaction ID.

Refined Abstraction - http://en.wikipedia.org/wiki/Bridge_Pattern

Transport for Serial protocols. Refined Abstraction - http://en.wikipedia.org/wiki/Bridge_Pattern

Gets or sets a value indicating whether LRC/CRC frame checking is performed on messages.

Modbus transport. Abstraction - http://en.wikipedia.org/wiki/Bridge_Pattern

This constructor is called by the NullTransport.

Number of times to retry sending message after encountering a failure such as an IOException, TimeoutException, or a corrupt message.

If non-zero, this will cause a second reply to be read if the first is behind the sequence number of the request by less than this number. For example, set this to 3, and if when sending request 5, response 3 is read, we will attempt to re-read responses.

If set, Slave Busy exception causes retry count to be used. If false, Slave Busy will cause infinite retries

Gets or sets the number of milliseconds the tranport will wait before retrying a message after receiving an ACKNOWLEGE or SLAVE DEVICE BUSY slave exception response.

Gets or sets the number of milliseconds before a timeout occurs when a read operation does not finish.

Gets or sets the number of milliseconds before a timeout occurs when a write operation does not finish.

Gets the stream resource.

Gets the logger for this instance.

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

Check whether we need to attempt to read another response before processing it (e.g. response was from previous request)

Provide hook to check whether receiving a response should be retried

Provide hook to do transport level message validation.

Releases unmanaged and - optionally - managed resources

true to release both managed and unmanaged resources; false to release only unmanaged resources.

Concrete Implementor - http://en.wikipedia.org/wiki/Bridge_Pattern This implementation is for sockets that Convert Rs485 to Ethernet.

Concrete Implementor - http://en.wikipedia.org/wiki/Bridge_Pattern

Concrete Implementor - http://en.wikipedia.org/wiki/Bridge_Pattern

Writes using Debug.WriteLine().

Base class for Modbus loggers.

Returns true if the level should be loggged, false otherwise.

Log the specified message at the specified level.

Override this method to implement logging behavior. This function will only be called if ShouldLog(level) is true.

Empty logger.

Singleton.

This won't do anything.

Always returnsa false

Abstract Modbus message.

Abstract Modbus message.

Abstract Modbus message.

Methods specific to a modbus request message.

Validate the specified response against the current request.

Modbus message factory.

Create a Modbus message.

Modbus message type. Bytes of Modbus frame. New Modbus message based on type and frame bytes.

Class holding all implementation shared between two or more message types. Interfaces expose subsets of type specific implementations.

Returns a that represents the current .

A that represents the current .

Write Multiple Coils request.

Write Multiple Coils request.

Write Multiple Coils request.

Defines constants related to the Modbus protocol.

The "built-in" message handlers.

Create a factory which uses the built in standard slave function handlers.

Create a factory which optionally uses the built in function services and allows custom services to be added.

User provided function services. If true, the built in function services are included. Otherwise, all function services will come from the functionService parameter. Logger

Supported function codes

502: mbap/TCP

802: mbap/TLS/TCP

Represents slave errors that occur during communication.

Initializes a new instance of the class.

Initializes a new instance of the class.

The message.

Initializes a new instance of the class.

The message. The inner exception.

Initializes a new instance of the class.

The that holds the serialized object data about the exception being thrown. The that contains contextual information about the source or destination. The class name is null or is zero (0). The info parameter is null.

Gets a message that describes the current exception.

The error message that explains the reason for the exception, or an empty string.

Gets the response function code that caused the exception to occur, or 0.

The function code.

Gets the slave exception code, or 0.

The slave exception code.

Gets the slave address, or 0.

The slave address.

When overridden in a derived class, sets the with information about the exception.

The that holds the serialized object data about the exception being thrown. The that contains contextual information about the source or destination. The info parameter is a null reference (Nothing in Visual Basic).

Modbus slave exception codes

The function code received in the query is not an allowable action for the slave. This may be because the function code is only applicable to newer devices, and was not implemented in the unit selected. It could also indicate that the slave is in the wrong state to process a request of this type, for example because it is unconfigured and is being asked to return register values. If a Poll Program Complete command was issued, this code indicates that no program function preceded it.

The data address received in the query is not an allowable address for the slave. More specifically, the combination of reference number and transfer length is invalid. For a controller with 100 registers, a request with offset 96 and length 4 would succeed, a request with offset 96 and length 5 will generate exception 02.

A value contained in the query data field is not an allowable value for the slave. This indicates a fault in the structure of remainder of a complex request, such as that the implied length is incorrect. It specifically does NOT mean that a data item submitted for storage in a register has a value outside the expectation of the application program, since the MODBUS protocol is unaware of the significance of any particular value of any particular register.

An unrecoverable error occurred while the slave was attempting to perform the requested action.

Specialized use in conjunction with programming commands. The slave has accepted the request and is processing it, but a long duration of time will be required to do so.T his response is returned to prevent a timeout error from occurring in the master.The master can next issue a Poll Program Complete message to determine if processing is completed.

Specialized use in conjunction with programming commands. The slave is engaged in processing a long-duration program command.The master should retransmit the message later when the slave is free.

Possible options for DiscriminatedUnion type.

Option A.

Option B.

A data type that can store one of two possible strongly typed options.

The type of option A. The type of option B.

Gets the value of option A.

Gets the value of option B.

Gets the discriminated value option set for this instance.

Factory method for creating DiscriminatedUnion with option A set.

Factory method for creating DiscriminatedUnion with option B set.

Returns a that represents the current .

A that represents the current .

Modbus utility methods.

Converts four UInt16 values into a IEEE 64 floating point format.

Highest-order ushort value. Second-to-highest-order ushort value. Second-to-lowest-order ushort value. Lowest-order ushort value. IEEE 64 floating point value.

Converts two UInt16 values into a IEEE 32 floating point format.

High order ushort value. Low order ushort value. IEEE 32 floating point value.

Converts two UInt16 values into a UInt32.

Converts an array of bytes to an ASCII byte array.

The byte array. An array of ASCII byte values.

Converts an array of UInt16 to an ASCII byte array.

The ushort array. An array of ASCII byte values.

Converts a network order byte array to an array of UInt16 values in host order.

The network order byte array. The host order ushort array.

Converts a hex string to a byte array.

The hex string. Array of bytes.

Calculate Longitudinal Redundancy Check.

The data used in LRC. LRC value.

Calculate Cyclical Redundancy Check.

The data used in CRC. CRC value.