PN 305200901, Rev YT
Serial Communication Interface (Modbus
®
)
This section 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 3050 Analyzer supports both RS-485 and RS-232 serial communication
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 four-wire and two-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 Congurator Software, which is supplied with
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.
The SerialMode variable could be set as follows:
Value RS-485 Protocol
0 Two-Wire ASCII
1 Four-Wire ASCII
2 Two-Wire MODBUS
3
Four-Wire MODBUS
The default SerialMode parameter setting is ‘1’.
Serial Communication Interface | 6-1
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