ModbusClient_TCP

ModbusClient_TCP (FB)

FUNCTION_BLOCK ModbusClient_TCP EXTENDS ModbusClientBase

Function description

This function block provides the client functionalities in a Modbus-TCP communication. The counterpart must provide the server functionalities. In the ideal case ( = complete reception of the Modbus response telegram within one task cycle time ) a new transmission is started cyclically after T = 5 * task cycle time ( T = 50ms for a task cycle time of 10ms ). For Modbus telegrams with a lot of data and/or low transmission rates on the serial side (RS485) this duration can increase accordingly. InOut:

Scope	Name	Type	Initial	Comment	Inherited from
Output	xConnected	BOOL		TRUE if connection has been established	ModbusClientBase
Output	xLicenceValid	BOOL		TRUE if a valid licence was found	ModbusClientBase
Input	xEn	BOOL	TRUE	Input to enable / disable the function block
Input	sHostAddress	STRING	‘’	Hostname (FQDN, e.g. 'www.focus.de') or IP address of the server (e.g. '192.168.178.210') (Modbus-TCP)
Input	wPort	WORD	502	Port number of the server (Modbus-TCP) (502 is the default port)
Input	xResetLastErrors	BOOL	FALSE	Input to reset the error outputs (rising edge)
Output	byLastRequestUnitID	BYTE	0	Last request telegram: Unit ID (0 = no unit)
Output	eState	Client_TCP_StateCode	Client_TCP_StateCode.IDLE	Current state of the state machine as ENUM
Output	eResponseState	Client_TCP_Response_StateCode	Client_TCP_Response_StateCode.NO_ERROR	Last response telegram: Description of the state as ENUM
Output	byLastErrorUnitID	BYTE	0	Last error: Unit ID (0 = no unit)
Output	xError	BOOL	FALSE	Current error state (FALSE = no error, TRUE = error)
Output	eLastErrorCode	Client_TCP_ErrorCode	Client_TCP_ErrorCode.NO_ERROR	Last error: Description of the communication error as ENUM
Output	xReady	BOOL	FALSE	Current standby state (FALSE = not ready, TRUE = ready to send/receive Modbus data)
Input Const	tKeepAliveTimeout	TIME	TIME#1m20s0ms	Time between the last packet sent and the first probe ( idle mode)
Input Const	tTimeoutDeviceReceive	TIME	TIME#2s0ms	Timeout for the device communication (read)
Input Const	tTimeoutDeviceSend	TIME	TIME#2s0ms	Timeout for the device communication (send)
Input Const	tTimeoutConnect	TIME	TIME#3s0ms	Timeout for the client-server communication (resolve = name resolution & connection time)