ModbusReadRegister (Function)

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ModbusReadRegister (Function)

In french: ModbusLitRegistre

Reads one or more registers from a Modbus slave, starting at a specific address.

Example

// Crée une session et connexion à un serveur Modbus
Session is modbusSession
Session = ModbusConnectTCP("192.168.1.7")

tabRéponse is array of 5 2-byte int

// Si la connexion échoue, affiche l'erreur
IF ErrorOccurred = True THEN
	Trace(ErrorInfo())
ELSE
	// Lit une séquence de 5 registres en lecture-écriture à partir de l'adresse 0x42.
	tabRéponse = ModbusReadRegister(Session, 0x42, 5, False)
	// Si il y a eu une erreur on l'affiche.
	IF ErrorOccurred = True THEN
		Trace(ErrorInfo())
	END
END

// Déconnexion
ModbusDisconnect(Session)

Syntax

Reading 1 register from a Modbus slave Hide the details

<Result> = ModbusReadRegister(<Session> , <Address> , <Read-only>)

<Result>: Integer

Value of the register read (16-bit integer).

<Session>: modbusSession variable

Name of the modbusSession variable that corresponds to the communication session with the Modbus slave.

<Address>: Integer

Address of the register in the slave (between 0 and 65,535).

<Read-only>: Boolean

True if the registers to be read are part of read-only data (Modbus function code 4 (Read Input Registers)).
False if the registers to be read are part of read-write data (Modbus function code 3 (Read Multiple Holding Registers)).

Reading multiple registers from a Modbus slave Hide the details

<Result> = ModbusReadRegister(<Session> , <Address> , <Number of registers> , <Read-only>)

<Result>: Array

Array of 16-bit integers that contains the values of the registers read.

<Session>: modbusSession variable

Name of the modbusSession variable that corresponds to the communication session with the Modbus slave.

<Address>: Integer

Starting address of the registers in the slave (between 0 and 65,535).

<Number of registers>: Integer

Number of registers to be read.

<Read-only>: Boolean

True if the registers to be read are part of read-only data (Modbus function code 4 (Read Input Registers)).
False if the registers to be read are part of read-write data (Modbus function code 3 (Read Multiple Holding Registers)).

Remarks

This function blocks the application until the slave responds to the message or until the session timeout is exceeded.
After calling ModbusReadRegister, it is recommended to check the ErrorOccurred variable to make sure there are no errors.

Business / UI classification: Neutral code

Component: wd300com.dll