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Modbus field bus – Burkert Type 8056 User Manual

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RS232_485_ETP_MODBUS_BU_REV02.doc

5.

MODBUS FIELD BUS

5.1.

INTRODUCTION

In this section of the manual there is the description of the Modbus field bus implemented in the
converter.
The Modbus field bus is available in the RS232 and RS485 serial port of the converter.


5.2.

RS485 HARDWARE CONNECTION


For the hardware connection see the relative section in this manual.


5.3.

DATA WORD FORMAT

The data bytes travelling in serial form on the communication line are enclosed in

words

which have a fixed length of

10 bits:

1 START BIT
8 DATA BITS = 1 BYTE DI DATI

1 STOP BIT

Each word contains one byte of data plus additional bits which serve to synchronise and make the communication

safer. These extra bits are added automatically in the transmission phase by the transmitter integrated circuit. In the
reception phase, the reverse operation is executed by the receiver integrated circuit: the eight data bits are extracted

and the others are eliminated. These operations are executed entirely on a hardware level.
The 8 data bits must be serialised staring from bit 0 (the least significant one).

5.4.

COMMUNICATION SPEED

The millennium series instruments have 4 communication speeds::

4800

bps

9600

bps

19200

bps

38400

bps


5.5.

SERIAL PORT SETTINGS


Serial port settings:

• Data bits: 8

• Parity: Menu «7-Communication», function - «Parity»

• Stop bits: 1

• Flow control: none (no control lines no xon/xoff characters used)

This manual is related to the following products: