Sensepoint XCD RFD Technical Manual SPXCDHMRFEN Issue 4_08-2016
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4.4 Options
4.4.1 Modbus
®
One of the most common eld buses in the industry, the optional Modbus
®
interface allows
the XCD to connect to a bus of devices and transmit data to PLCs or controllers (see
Appendix A). Connections to the XCD are made through a pluggable terminal block on
the Modbus
®
interface circuit board. Modbus
®
RTU protocol uses ASCII/Hex protocols for
communication. And allows all transmitter/sensor front panel functions to be transmitted
using this industrial eldbus.
Modbus
®
protocol is a Master-Slaves protocol. Only one master (at the same time) is
connected to the bus and one or up to 32 slave nodes are also connected to the same
serial bus. Modbus
®
communication is always initiated by the master. The slave nodes will
never transmit data without receiving a request from the master node. The slave nodes
will never communicate with each other. The master node initiates only one Modbus®
transaction at the same time.
The MODBUS
®
may only be used for data collection or record keeping with regard to
combustible gas detection and not for performance verication.
Modbus
®
option is available only for selected gases. Please refer to chapter 15 Ordering
information.
To nd out if a unit has the Modbus
®
option tted, look at the part number on the product
label. Units tted with Modbus
®
have the letter “M” at the end of the part number.
Note: MODBUS
®
is a registered trademark of Schneider Automation Inc.
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