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IN701-KNX Series
KNX to Modbus Client
5. KNX to Modbus Client
5.1. Specific Introduction
This section describes the integration of Modbus RTU installations into KNX systems using the KNX to Modbus
client application of the Intesis gateway.
This integration allows a KNX control system or device to access the signals and resources of Modbus systems as
if they were part of the KNX system and vice versa.
The gateway acts as a Modbus RTU client device in its Modbus interface, reading/writing points from the
Modbus server devices by automatic continuous polling. The gateway offers these points' values through its KNX
interface, acting as one more KNX device of the system.
The gateway configuration is carried out through the configuration tool.
Figure 2. Integration of Modbus RTU or TCP devices into KNX control and monitoring systems
5.2. Functionality
From the Modbus system point of view, after starting it, the Intesis gateway continuously reads the Modbus RTU
service devices, updating all the points' values received in its memory.
From the KNX system point of view, after starting the gateway or performing a KNX bus reset, the Intesis gateway
polls the KNX signals and stores the received values in its memory, ready to be served to the Modbus system
when requested. It also listens for any KNX telegram related to the internal points configured in it and acts
accordingly to the configuration of the related points.
In the gateway, each Modbus point is associated with a KNX group address so that the KNX system sees
the whole Modbus system as if it was one more KNX device with the same configuration and operation
characteristics.
When a Modbus point changes, the gateway sends a write telegram to the associated group address in the KNX
bus.
When the gateway receives a telegram from a KNX group address associated with a Modbus point, it sends a
message to the corresponding Modbus device to perform the related action.
Page 6 of 44
USER MANUAL Version 1.0
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