SD01189C/07/EN/04.17
Endress+Hauser
5
2 Installation and wiring
Installation and wiring is described in detail in the operating instructions of each product.
2.1 A-, B-wire
The 485/ETH communication module uses the same connector labeling as for PROFIBUS devices. It has to
be stated that the usage of A and B is not consistent over all available Modbus devices. The 485/ETH
modules use the following definition:
Received/transmitted data - P
Received/transmitted data - N
Data reference potential output
In case RS485 communication is not working, please verify that the RS485-signals are connected
correctly, otherwise switch the signals. Switching the RS485-signals does not damage the RS485 interface
of the device.
2.2 Termination
The communication module provides the possibility of activating a bus termination via a 4-pin DIL slide
switch. Here, the downstream Modbus devices are not separated from the Modbus RS485 segment. The
communication module must be removed to activate the bus termination. If the communication module is
installed and supplied with voltage, the bus termination state is indicated by the T LED (yellow).
The termination is according the definition for PROFIBUS DP, as the RS485 interface can be used for
PROFIBUS DP communication.
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