MBSlaveRTUex

Function Block - MODBUS RTU Slave protocol on serial port.

Inputs

Input	Data type	Description
IN	BOOL	Enabling command: the port is open when this input is TRUE.
PORT	STRING	Settings string for the serial port (e.g. 'COM1:9600,N,8,1').
SLV	DINT	MODBUS slave number.
SrvID	STRING	MBSlaveRTUex only: ID of the server in the configuration.

Outputs

Output	Data type	Description
Q	BOOL	TRUE if the port is successfully open.

Remarks

When active, this function block manages the MODBUS RTU Slave protocol on the specified serial communication port. The configuration of the MODBUS Slave map (designing MODBUS addresses) is done using the MODBUS configuration tool, from the Fieldbus Configurator.

There can be several instances of the MBSlaveRTU working simultaneously on different serial ports. Other MODBUS Slave connections (TCP server, UDP) can also be active at the same time.

The slave number entered in the MODBUS Slave configuration tool is ignored when MODBUS Slave protocol is handled by this function block. Instead, the SLV input specifies the MODBUS slave number.

With MBSlaveRTUex, you can specify the ID of a server from the MODBUS slave configuration. If you specify an empty string, the first server is used. MBSlaveRTU always works with the first server in the configuration.

ST Language

MySlave is a declared instance of MBSlaveRTU function block.

MySlave (IN, PORT, SLV, SrvID);
Q := MySlave.Q;

MBSlaveRTUex

IEC 61131-3 Automation platform > Programming - Reference guide > Driver specific function blocks > Modbus Slave > MBSlaveRTUex

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