PN 305725901, Rev YF
Serial Communication Interface (Modbus)
This document describes the customer serial communication interface on the
3050 Analyzer. The communication protocol implemented is Modicon
Modbus
®
as dened in “Modicon Modbus Protocol Reference Guide”
(PI-MBUS-300 RevJ). The Modbus protocol transmission mode implemented is
Remote Terminal Unit (RTU) with the analyzer operating as a slave device.
The AMETEK 3050 Analyzer supports both RS-485 and RS-232 serial communi-
cation standards.
The physical communication connection between a 3050 Analyzer and a
customer DCS\SCADA\PLC\DAS or a general-purpose computer is RS-485
or RS-232. The analyzer RS-485 connection supports both 4-wire and 2-wire
multi-drop systems. The RS-232 connection is used to communicate with a
single analyzer using short standard cable.
The 3050 Analyzer understands two serial communication protocols. The rst
protocol is a proprietary ASCII serial communication protocol. This protocol is
supported by AMETEK 3050 Analyzer Congurator Software, which supplied
with the each analyzer. This program provides a graphical user interface to set
up all the analyzer parameters as explained in Chapter 3.
The variable called SerialMode allows switching communication protocol from
AMETEK ASCII to Modbus protocol and back from Modbus to AMETEK ASCII.
This variable can be reached from AMETEK ASCII protocol by ID=38(26Hex)
and SerialMode can be modied by modifying holding register #28(4029), as
indicated in the holding registers table.
SerialMode variable could be set as follows:
Value RS-485 Protocol
0 2-Wire ACII
1 4-Wire ACII
2 2-Wire Modbus
3 4-Wire Modbus
The SerialMode parameter is set to ‘1’ by default.
Serial Communication Interface | 6-1
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