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4. Properties Vlinx MESR9xx Modbus Gateway

Page 27 Manual Documentation Number MESR9xx-0109m

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Modbus Message Buffering

The MESR9xx has two Modbus serial buffers, one for each serial port. Each will buffer

up to 32 Modbus messages. These buffers help ensure messages don’t get lost in a data

traffic jam, and are part of what makes Modbus such an outstandingly reliable serial

protocol.

Modbus Message Timeout

Message timeout is supported by the MESR9xx. This is the maximum amount of time

before a response to a message is expected.

Modbus RTU Message

The Modbus RTU message is broken into 4 different parts. The address field, the

function code, this is copied directly over from the Modbus TCP message, the data and

the error check, a 16 bit cyclic redundancy check or CRC.

Modbus Serial Control

Message Timeout

The message timeout is the maximum time the gateway allows for a response from the

slave device. The default is 1000ms.

Character Timeout

The character timeout is the maximum time the gateway allows between characters from

the slave device, used only in RTU mode. The default is 10ms.

CRC/LRC Error Check

The CRC/LRC check calculates the CRC/LRC for the message received, and compares

this to the CRC/LRC with the message. If not the same the message is rejected.

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B&B Electronics ESR901 Especificaciones Pagina 31