Modbus Communications; Host Computer Serial Communications - ABB Endura AZ40 Operating Instructions Manual

4 MODBUS communications

IMPORTANT (NOTE)
MODBUS menus are enabled only if a MODBUS
communications module is fitted.
This section describes the connection of serial data cables
between the master (host computer) and slave (Endura AZ40
transmitter) on a MODBUS serial link.
Menu
MODBUS
Device Address
RS485 Setup
Mode
Baud Rate
Parity
Tx Delay

4.1 Host computer serial communications

The serial interface option module operates using the MODBUS
Remote Terminal Unit (RTU) Master / Slave protocol. An
appropriate RS422 / 485 communications driver must be fitted
to the host (master) computer. It is strongly recommended that
the interface has galvanic isolation to protect the computer
from lightning damage and to increase signal immunity to noise
pick-up.
IMPORTANT (NOTE)
The MODBUS option provides the following facilities:
— Standard RS422/485 communications.
— MODBUS RTU protocol – the transmitter is
designed to operate as a Remote Terminal Unit
(RTU) slave when communicating with a master
(host) system.
— 500V DC isolation from external connections to the
instrument.
— 2- or 4-wire communication (selected at the RS485
Setup / Mode parameter).
— 1200, 2400, 4800, 9600, 19200, 38400, or 115200
baud transmission rate.
— Parity-checking (odd, even or none).
8 COM/AZ40/MOD–EN Rev. A | Endura AZ40 | Oxygen and carbon monoxide equivalent (COe) analyzer
Comment
Set a device-specific address (from 1 to 247) to identify the transmitter on a
MODBUS link.
Select the MODBUS serial communication serial link type:
2 Wire, 4 Wire or Off
Select a communication transfer rate:
1200, 2400, 4800, 9600, 19200, 38400 or 115200 baud.
Select the parity bit (transmission error-checking) condition:
No Parity, Odd Parity or Even Parity
Set a delay to the response from the transmitter in milliseconds.
Maximum delay 100 ms.
DANGER – Serious damage to health / risk to life
Refer to the Endura AZ40 Operating instruction
(OI/AZ40-EN) before making electrical connections.
Default
4 Wire
19200
No Parity
50 ms