Modbus Registers

Callback function used if a Coil Register value is read or written by the protocol stack. If you are going to use this function you might use the functions xMBUtilSetBits( ) and xMBUtilGetBits( ) for working with bitfields.

Parameters:

pucRegBuffer	The bits are packed in bytes where the first coil starting at address usAddress is stored in the LSB of the first byte in the buffer pucRegBuffer. If the buffer should be written by the callback function unused coil values (I.e. if not a multiple of eight coils is used) should be set to zero.
usAddress	The first coil number.
usNCoils	Number of coil values requested.
eMode	If eMBRegisterMode::MB_REG_WRITE the application values should be updated from the values supplied in the buffer pucRegBuffer. If eMBRegisterMode::MB_REG_READ the application should store the current values in the buffer pucRegBuffer.

Returns:

The function must return one of the following error codes:

• eMBErrorCode::MB_ENOERR If no error occurred. In this case a normal Modbus response is sent.
• eMBErrorCode::MB_ENOREG If the application does not map an coils within the requested address range. In this case a ILLEGAL DATA ADDRESS is sent as a response.
• eMBErrorCode::MB_ETIMEDOUT If the requested register block is currently not available and the application dependent response timeout would be violated. In this case a SLAVE DEVICE BUSY exception is sent as a response.
• eMBErrorCode::MB_EIO If an unrecoverable error occurred. In this case a SLAVE DEVICE FAILURE exception is sent as a response.

Definition at line 135 of file main.cpp.

Callback function used if a Input Discrete Register value is read by the protocol stack.

If you are going to use his function you might use the functions xMBUtilSetBits( ) and xMBUtilGetBits( ) for working with bitfields.

Parameters:

pucRegBuffer	The buffer should be updated with the current coil values. The first discrete input starting at usAddress must be stored at the LSB of the first byte in the buffer. If the requested number is not a multiple of eight the remaining bits should be set to zero.
usAddress	The starting address of the first discrete input.
usNDiscrete	Number of discrete input values.

Returns:

The function must return one of the following error codes:

• eMBErrorCode::MB_ENOERR If no error occurred. In this case a normal Modbus response is sent.
• eMBErrorCode::MB_ENOREG If no such discrete inputs exists. In this case a ILLEGAL DATA ADDRESS exception frame is sent as a response.
• eMBErrorCode::MB_ETIMEDOUT If the requested register block is currently not available and the application dependent response timeout would be violated. In this case a SLAVE DEVICE BUSY exception is sent as a response.
• eMBErrorCode::MB_EIO If an unrecoverable error occurred. In this case a SLAVE DEVICE FAILURE exception is sent as a response.

Definition at line 142 of file main.cpp.

Callback function used if a Holding Register value is read or written by the protocol stack. The starting register address is given by usAddress and the last register is given by usAddress + usNRegs - 1.

Parameters:

pucRegBuffer	If the application registers values should be updated the buffer points to the new registers values. If the protocol stack needs to now the current values the callback function should write them into this buffer.
usAddress	The starting address of the register.
usNRegs	Number of registers to read or write.
eMode	If eMBRegisterMode::MB_REG_WRITE the application register values should be updated from the values in the buffer. For example this would be the case when the Modbus master has issued an WRITE SINGLE REGISTER command. If the value eMBRegisterMode::MB_REG_READ the application should copy the current values into the buffer pucRegBuffer.

Returns:

The function must return one of the following error codes:

• eMBErrorCode::MB_ENOERR If no error occurred. In this case a normal Modbus response is sent.
• eMBErrorCode::MB_ENOREG If the application can not supply values for registers within this range. In this case a ILLEGAL DATA ADDRESS exception frame is sent as a response.
• eMBErrorCode::MB_ETIMEDOUT If the requested register block is currently not available and the application dependent response timeout would be violated. In this case a SLAVE DEVICE BUSY exception is sent as a response.
• eMBErrorCode::MB_EIO If an unrecoverable error occurred. In this case a SLAVE DEVICE FAILURE exception is sent as a response.

Definition at line 91 of file main.cpp.

Callback function used if the value of a Input Register is required by the protocol stack. The starting register address is given by usAddress and the last register is given by usAddress + usNRegs - 1.

Parameters:

pucRegBuffer	A buffer where the callback function should write the current value of the modbus registers to.
usAddress	The starting address of the register. Input registers are in the range 1 - 65535.
usNRegs	Number of registers the callback function must supply.

Returns:

The function must return one of the following error codes:

• eMBErrorCode::MB_ENOERR If no error occurred. In this case a normal Modbus response is sent.
• eMBErrorCode::MB_ENOREG If the application can not supply values for registers within this range. In this case a ILLEGAL DATA ADDRESS exception frame is sent as a response.
• eMBErrorCode::MB_ETIMEDOUT If the requested register block is currently not available and the application dependent response timeout would be violated. In this case a SLAVE DEVICE BUSY exception is sent as a response.
• eMBErrorCode::MB_EIO If an unrecoverable error occurred. In this case a SLAVE DEVICE FAILURE exception is sent as a response.

Definition at line 63 of file main.cpp.