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BACnet Server to Modbus Client
IN700-485 Series
4. BACnet Server to Modbus Client
4.1. Specific Gateway Introduction
This section describes the integration of Modbus RTU and/or Modbus TCP installations into BACnet IP or MSTP
control and monitoring systems using the BACnet Server to Modbus Client application.
This integration allows a Modbus control system to access the signals and resources of BACnet systems as if they
were part of the Modbus system itself and vice versa.
The gateway configuration is carried out through the configuration tool.
Figure 1. Integration of Modbus RTU or TCP devices into BACnet IP or MSTP control and monitoring systems
4.2. Functionality
From the Modbus point of view, the gateway continuously polls the installation or devices, storing in its memory
the values of the points that you previously configured to be read. On the other hand, from the BACnet point of
view, the control and monitoring system reads and writes those stored points.
This is possible because, inside the gateway, all Modbus registers of the server devices are associated with
BACnet objects. This makes the BACnet control and monitoring system perceive the Modbus installation (all the
server devices) as if it were a single BACnet device.
When the gateway polls the Modbus devices, if a non-response is detected, the corresponding virtual signal
inside the gateway will be activated, indicating the communication error to the BACnet system.
The gateway has two EIA-485 ports for Modbus RTU integration: Port A and Port B. This function allows you to
integrate up to 64 devices (32 in each port) with no additional repeaters in the network.
This functionality is disabled when BACnet MSTP is selected in Intesis MAPS, leaving only Port A available for
Modbus RTU connectivity and Port B for BACnet MSTP devices.
By default, Port A is configured for Modbus RTU and Port B for BACnet MSTP.
USER MANUAL Version 1.0
Page 5 of 36
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