KROHNE IFC 050 Converter Modbus EN - Manual (Page 5)

CONNECTION IN BUS SYSTEMS
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IFC 050
www.krohne.com 09/2012 - 4002202601 - AD Modbus IFC 050 R01 en
For proper operation of Modbus in half duplex mode in single or multi-drop communication, it is
recommended that a termination resistor is applied to both ends of the data line. The simplest
form of termination is line-to-line resistor across the differential input.
In RTU mode the Modus protocol requires quiet periods on the communications bus for
synchronisation. It is therefore important that the Modbus is not allowed to "float", i.e.
unreferenced to 0 V, as this could lead to spurious signals due to noise pick-up. It is therefore
necessary to employ biasing resistors at one point on the bus network, normally the "end".