modbus

package
v0.0.1 Latest Latest
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 Go to latest Published: Apr 9, 2020 License: Apache-2.0 Imports: 5 Imported by: 4

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Constants

View Source 
const (
	// Bit access
	FuncCodeReadDiscreteInputs FunctionCode = 2
	FuncCodeReadCoils                       = 1
	FuncCodeWriteSingleCoil                 = 5
	FuncCodeWriteMultipleCoils              = 15

	// 16-bit access
	FuncCodeReadInputRegisters         = 4
	FuncCodeReadHoldingRegisters       = 3
	FuncCodeWriteSingleRegister        = 6
	FuncCodeWriteMultipleRegisters     = 16
	FuncCodeReadWriteMultipleRegisters = 23
	FuncCodeMaskWriteRegister          = 22
	FuncCodeReadFIFOQueue              = 24
)

Defined valid function codes

Variables

This section is empty.

Functions

func DecodeASCIIByte 

func DecodeASCIIByte(data []byte) (byte, []byte, error)

DecodeASCIIByte converts type ascii hex bytes to a binary byte

func DecodeASCIIByteEnd 

func DecodeASCIIByteEnd(data []byte) (byte, []byte, error)

DecodeASCIIByteEnd converts type ascii hex bytes to a binary byte. This function takes from the end of the slice

Types

type FuncReadHoldingRegisterResponse 

type FuncReadHoldingRegisterResponse struct {
	FunctionCode FunctionCode
	RegCount     byte
	RegValues    []uint16
}

FuncReadHoldingRegisterResponse response to read holding reg

type FuncReadHoldingRegistersRequest 

type FuncReadHoldingRegistersRequest struct {
	FunctionCode    FunctionCode
	StartingAddress uint16
	RegCount        uint16
}

FuncReadHoldingRegistersRequest represents the request to read holding reg

type FuncWriteMultipleRegisterRequest 

type FuncWriteMultipleRegisterRequest struct {
	FunctionCode    FunctionCode
	StartingAddress uint16
	RegCount        uint16
	ByteCount       byte
	RegValues       []uint16
}

FuncWriteMultipleRegisterRequest represents the request to write multiple regs

type FunctionCode 

type FunctionCode byte

FunctionCode represents a modbus function code

type Modbus 

type Modbus struct {
	// contains filtered or unexported fields
}

Modbus is a type that implements modbus ascii communication. Currently, only "sniffing" a network is implemented

func NewModbus 

func NewModbus(port io.ReadWriter) *Modbus

NewModbus creates a new Modbus

func (*Modbus) Read 

func (m *Modbus) Read() ([]byte, error)

Read returns an ASCII modbus packet. Blocks until a full packet is received or error

type PDU 

type PDU struct {
	Address      byte
	FunctionCode FunctionCode
	Data         []byte
	LRC          byte
	End          []byte // should be "\r\n"
}

PDU is a modbus protocol data unit

func DecodeASCIIPDU 

func DecodeASCIIPDU(data []byte) (ret PDU, err error)

DecodeASCIIPDU decodes a ASCII modbus packet

func (*PDU) CheckLRC 

func (pdu *PDU) CheckLRC() bool

CheckLRC verifies the LRC is valid

func (*PDU) DecodeFunctionData 

func (pdu *PDU) DecodeFunctionData() (ret interface{}, err error)

DecodeFunctionData extracts the function data from the PDU

Source Files

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