ModbusConnectRTU (Function)

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ModbusConnectRTU (Function)

In french: ModbusConnecteRTU

Connects a client to a Modbus slave via a serial port.

Example

// Crée une session et connexion à l'esclave Modbus sur le port série COM4
Session is modbusSession
Session = ModbusConnectRTU("COM4",1)

// Si la connexion échoue, affiche l'erreur.
IF ErrorOccurred = True THEN
	Trace(ErrorInfo())
ELSE
	// Ecrit une valeur dans le registre 0x42 de l'esclave.
	ModbusWriteRegister(Session, 0x42,0xCAFE)
END

// Libère le port série
ModbusDisconnect(Session)

Syntax

<Session> = ModbusConnecteRTU(<Serial port> [, <Slave ID> [, <Rate> [, <Parity> [, <Nb data Bits> [, <Nb stop Bits>]]]]])

<Session>: modbusSession variable

modbusSession variable used to communicate with the Modbus slave.

<Serial port>: Character string

Name of serial port to be used: COM1, COM2, COM3, ... COM256.

<Slave ID>: Optional integer

Slave identifier, between 0 and 255.
By default, this parameter is set to 0 (broadcast address). Note: The value 0 can also be specified if the slave identifier is to be specified later via the IDEsclave property of variable type modbusSession.

<Rate>: Optional integer

Data transfer rate (expressed in baud or bits per second) to be used for serial connection. By default, this parameter is set to 9600 baud.

<Parity>: Optional integer

Transfer parity on the port:
0 No parity
1 Even parity
2 Odd parity
Note: There is no default parity.

<Nb data Bits>: Optional integer

Number of data bits on serial port: 5, 6, 7 or 8.

<Nb stop Bits>: Optional integer

Number of stop bits on the serial port:
0
(Default value) 1 stop bit
1 1.5 stop bits
2 2 stop bits

Remarks

After calling ModbusConnectRTU, it is recommended to check the ErrorOccurred variable to make sure there are no errors.
The slave identifier is in the modbusSession variable. If an operation is to be performed on several different slaves, you can change the slave identifier in the modbusSession variable to avoid reopening the session.

Business / UI classification: Business Logic

Component: wd300com.dll