MGS-250 Manual
6490-9000 Revision 4
49
Section 7. Modbus Communications
7.1. Introduction
The MGS-250 gas detector can be configured to communicate on an
RS-485 network using Modbus-RTU protocol. Before configuring the
gas detector for Modbus communications, be sure your network
connection is complete and your network termination switches are set
appropriately. Refer to Chapter 3 (Wiring and Configuration) for details.
This section details the MGS-250 parameters that can be accessed via
registers of the Modbus-RTU (“Modbus”) protocol. Generally (with the
exception of some of the communications parameters), parameters you
can access and/or configure from the front panel of the MGS-250 can
also be accessed and/or configured via a Building Management System
(for example) on the same Modbus network.
7.2. Communications Settings
There are 255 selections available to be set electronically, from
addresses 1 to 255 inclusive. Modbus data with a zero in the address
field is received by all detectors (regardless of the address selected) to
enable the master device to broadcast simultaneously to all the
detectors.
Refer to the specifications section (page 16) for information on RS-485
network communications parameters such as data bits, stop bits, etc.
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