User`s manual
Chapter 4 Serial Communications AX2200/AX2300 Instruction Manual
4-12 CM2-AX2000-2001 (Rev. 4, 4/2014)
Modbus Communications
Applicable Flow Meter Models
azbil AX2000Series Mass Flow Meters, Models AX2200 and AX2300 with
Modbus communication protocol and firmware version 4.00.58 and above.
Overview
This document describes the preliminary implementation of the Modbus
communication protocol for use in monitoring common process variables in the
azbil AX2000Series Vortex flow meter. The physical layer utilizes the half-
duplex RS-485 port, and the Modbus protocol.
Reference Documents
The following documents are available online from www.modbus.org.
Modbus Application Protocol Specification V1.1
Modbus Over Serial Line Specification & Implementation Guide V1.0
Modicon Modbus Protocol Reference Guide PI–MBUS–300 Rev. J
Wiring
An RS485 daisy chained network configuration as depicted below is
recommended. Do not use a star, ring, or cluster arrangement.
RS-485 -
RS-485 +
RS-485 GND
RS-485 Master
Vortex Meter
Other Device 2, etc.Other Device 1
Figure 4-4.RS-485 Wiring (MODBUS)
Pin Labeling (among devices)
“RS-485 –” = “A” = “TxD-/RxD-” = “Inverting pin”
Warning!
Place controls in manual
mode when making
configuration changes to
the vortex meter.