IntesisBox
®
BACnet/IP Server - Modbus RTU Master
User’s Manual r14 eng
© Intesis Software S.L. - All rights reserved
This information is subject to change without notice
IntesisBox
®
is a registered trademark of Intesis Software SL
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2. Interfaces
This section gives the reader an idea on how a Modbus system/installation is integrated with
IntesisBox BACnet. It is not meant to provide an in-depth explanation on how BACnet or
Modbus technology work as understanding the protocol principles is assumed throughout
this document.
The IntesisBox behaves as a regular BACnet device inside the BACnet system integrating all
the KNX devices. Note that each datapoint defined on IntesisBox will have two associated
data types:
One data-type, related to the BACnet/IP protocol of the IntesisBox
And another data-type, related to Modbus side of IntesisBox
Conversions of data values from Modbus to BACnet/IP data-types (and vice versa) are
internally performed at application level of IntesisBox, and keeping the highest possible
level of precision, with the restrictions of the data-type itself. Further detail on behavior and
data-types of the BACnet/IP and Modbus interfaces of IntesisBox is given in the following
sections.
All configuration of IntesisBox BACnet is done using software tool
LinkBoxBacnet
. This tool,
covered in depth in section 5, is used to define the Modbus and BACnet related parameters
on each of the datapoints defined in IntesisBox.
2.1 BACnet
The IntesisBox integrates all the Modbus devices in a single BACnet device. The
communication with the other BACnet devices is done via the Ethernet port of the gateway
which implements the BACnet ASHRAE 135 – 2001 Annex J - BACnet protocol.
The supported BACnet Objects and Building Blocks can be found in the PICS document
available on the web:
http://www.intesis.com/pdf/IntesisBox_BACnet_IP_Server_Modbus_RTU_master_PICS.pdf
Configuration of all BACnet/IP parameters of IntesisBox and their links to Modbus using
LinkBoxBacnet software tool is covered in section 5.1.
2.2 Modbus
Modbus RTU communication is characterised by the co-existence of just one master and one
or more slave devices in a given network, all of them interconnected, and every slave with a
unique address into the network. Different types of networks and network topologies are
allowed. The more commonly used for Modbus RTU communication are: point to point
communication using RS232, and point to multipoint communication using RS485 (2-wire or
4-wire).
IntesisBox acts as the master in the Modbus network, and the other Modbus devices
connected to the network must be always slave devices. Up to 254 slave devices can be
defined in IntesisBox. The types of networks supported by IntesisBox are:
RS485 2-wire (up to 254 slave devices are allowed by IntesisBox, thus up to 254 slave
devices in the same RS485 network can be integrated with just one IntesisBox, installing
additional line repeaters where necessary).
