ModbusReadBit (Function)

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ModbusReadBit (Function)

In french: ModbusLitBit

Reads one or more bits 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 int

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

// Déconnexion
ModbusDisconnect(Session)

Syntax

Reading 1 bit from a Modbus slave Hide the details

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

<Result>: Boolean

Value of the bit read (True or False).

<Session>: modbusSession variable

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

<Address>: Integer

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

<Read-only>: Boolean

True if the bits to be read are part of read-only data (Modbus function code 2 (Read Discrete Inputs)).
False if the bits to be read are part of read-write data (Modbus function code 1 (Read Coils)).

Reading multiple bits from a Modbus slave Hide the details

<Result> = ModbusReadBit(<Session> , <Address> , <Number of bits> , <Read-only>)

<Result>: Array

Array of integers that contains the value of the bits read (True or False).

<Session>: modbusSession variable

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

<Address>: Integer

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

<Number of bits>: Integer

Number of bits to be read (to be sent by the slave).

<Read-only>: Boolean

True if the bits to be read are part of read-only data (Modbus function code 2 (Read Discrete Inputs)).
False if the bits to be read are part of read-write data (Modbus function code 1 (Read Coils)).

Remarks

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

Business / UI classification: Business Logic

Component: wd300com.dll