MbusSlaveServer Class Reference

Base class which implements the Modbus server engine. More...

Public Member Functions
virtual	~MbusSlaveServer ()
	Destructor. More...
int	addDataTable (int slaveAddr, MbusDataTableInterface *dataTablePtr)
	Associates a protocol object with a Data Provider and a Modbus slave ID. More...
virtual int	serverLoop ()=0
	Modbus slave server loop. More...
virtual void	shutdownServer ()=0
	Shuts down the Modbus server. More...
virtual int	isStarted ()=0
	Returns whether server has been started up. More...
int	getConnectionStatus ()
	Checks if a Modbus master is polling periodically. More...

Static Public Member Functions
static const TCHAR *	getPackageVersion ()
	Returns the library version number. More...

Protocol Configuration
int	setTimeout (long timeOut)
	Configures master activity time-out supervision. More...
long	getTimeout ()
	Returns the currently set master activity time-out value. More...
void	disableExceptionReplies ()
	Supress exception replies to be sent. More...
void	enableExceptionReplies ()
	Enables exception replies after they have been turned off. More...

Transmission Statistic Functions
unsigned long	getTotalCounter ()
	Returns how often a message transfer has been executed. More...
void	resetTotalCounter ()
	Resets total message transfer counter.
unsigned long	getSuccessCounter ()
	Returns how often a message transfer was successful. More...
void	resetSuccessCounter ()
	Resets successful message transfer counter.

Detailed Description

Base class which implements the Modbus server engine.

This class realises the server engine. The server engines processes Modbus messages, parses the function codes and upon receipt of a valid master query it calls Data Provider methods to exchange data with the user application. For a more detailed description which Modbus data and control functions have been implemented in the server engine see section Server Functions common to all Modbus Protocol Flavours.

See also

Server Functions common to all Modbus Protocol Flavours

MbusDataTableInterface, MbusRtuSlaveProtocol, MbusAsciiSlaveProtocol, MbusTcpSlaveProtocol

Constructor & Destructor Documentation

~MbusSlaveServer()

~MbusSlaveServer ( )

virtual

Destructor.

Shuts down server, closes any associated communication resources (serial ports or sockets) and releases any resources.

Member Function Documentation

addDataTable()

int addDataTable	(	int	slaveAddr,
		MbusDataTableInterface *	dataTablePtr
	)

Associates a protocol object with a Data Provider and a Modbus slave ID.

Parameters

slaveAddr	Modbus slave address for server to listen on (-1 - 255). 0 is regarded as a valid value for a MODBUS/TCP server address. A value of -1 means the server disregards the slave address and listens to all slave addresses. 0 or -1 is only valid for MODBUS/TCP!
dataTablePtr	Modbus data table pointer. Must point to a Data Provider object derived from the MbusDataTableInterface class. The Data Provider is the interface between your application data and the Modbus network.

Returns

FTALK_SUCCESS on success or error code. See Error Management for a list of error codes.

References FTALK_ILLEGAL_ARGUMENT_ERROR, and FTALK_SUCCESS.

serverLoop()

virtual int serverLoop ( )

pure virtual

Modbus slave server loop.

This server loop must be called continuously. It must not be blocked. The server has to be started before calling the serverLoop() method.

In most cases the server loop is executed in an infinite loop in its own thread:

while (notTerminated) {
  mbusProtocol.serverLoop();
}

Returns

FTALK_SUCCESS on success or error code. See Error Management for a list of error codes.

Implemented in MbusTcpSlaveProtocol, MbusRtuSlaveProtocol, MbusRtuOverTcpSlaveProtocol, MbusUdpSlaveProtocol, MbusAsciiSlaveProtocol, and MbusIpServerBase.

shutdownServer()

virtual void shutdownServer ( )

pure virtual

Shuts down the Modbus server.

This function also closes any associated communication resources like serial ports or sockets.

Implemented in MbusSerialServerBase, MbusTcpSlaveProtocol, MbusUdpSlaveProtocol, and MbusIpServerBase.

isStarted()

virtual int isStarted ( )

pure virtual

Returns whether server has been started up.

Return values

true	= started
false	= shutdown

Implemented in MbusSerialServerBase, and MbusIpServerBase.

getConnectionStatus()

int getConnectionStatus ( )

inline

Checks if a Modbus master is polling periodically.

Return values

true	= A master is polling at a frequency higher than the master transmit time-out value
false	= No master is polling within the time-out period

Note

The master transmit time-out value must be set > 0 in order for this function to work.

setTimeout()

int setTimeout

(

long

timeOut

)

Configures master activity time-out supervision.

The slave can monitor whether a master is actually polling or not. This function sets the activity time-out to the specified value. A value of 0 disables the time-out, which stops time-out notifications being sent to the Data Provider. Default value is 1000 ms.

Remarks

The time-out value is a minimum value only and the actual time may be longer. How precise it is followed depends on the operating system used, its scheduling priority and its system timer resolution.

Note

The time-out does not check whether a master is sending valid frames. The transmission of characters is sufficient to avoid the time-out.

Parameters

timeOut

Timeout value in ms (Range: 0 - 100000), 0 disables time-out

Return values

FTALK_SUCCESS	Success
FTALK_ILLEGAL_ARGUMENT_ERROR	Argument out of range

References FTALK_ILLEGAL_ARGUMENT_ERROR, and FTALK_SUCCESS.

getTimeout()

long getTimeout ( )

inline

Returns the currently set master activity time-out value.

Returns

Timeout value in ms

disableExceptionReplies()

void disableExceptionReplies

(

)

Supress exception replies to be sent.

With this option only positive replies are sent to the master. All failure replies are silently discarded. This option can be useful if redundant Modbus devices are used. In this scenario supressing the reply would trigger a swap-over of the redundant devices.

enableExceptionReplies()

void enableExceptionReplies

(

)

Enables exception replies after they have been turned off.

Sending exception replies in case of slave failures is the normal mode of operation.

getTotalCounter()

unsigned long getTotalCounter ( )

inline

Returns how often a message transfer has been executed.

Returns

Counter value

getSuccessCounter()

unsigned long getSuccessCounter ( )

inline

Returns how often a message transfer was successful.

Returns

Counter value

getPackageVersion()

const TCHAR * getPackageVersion ( )

static

Returns the library version number.

Returns

Version string