ModbusClient_TCP

ModbusClient_TCP (FB)

FUNCTION_BLOCK ModbusClient_TCP EXTENDS ModbusClientBase

Representation

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 = 50 ms for a task cycle time of 10 ms). For Modbus telegrams with a lot of data and/or low transmission rates on the serial side (RS 485) this time 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 package 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)