Burkert Type 8056 - Manual (Page 71)

- 71 - 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)