Hirschmann 943 893-321, Manual

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9
2 Half duplex operation
Version 1.0 03/06
2 Half-duplex operation
Fig. 2: Half-duplex mode
Port 1
Port 3 Port 2
Port 1
Port 3 Port 2
Port 1
Port 3 Port 2
Data Data Data
The data channel of the electrical port (Port 1) can trans-
mit data in half-duplex mode. It replaces a 2-wire cable.
In half-duplex mode, the arbitration procedure used by
the connected devices must ensure that at any given
time, only one device can access the bus, like in
master/slave operation. Access procedures where there
is a risk of collisions, such as CAN, are not permissible. In half-duplex mode, consecutive data telegrams must
be separated by a minimal time gap of 3.5 µs so that the
end of a data telegram can be definitively recognized and
thus the data direction can be switched in the OZD 485
G12 BAS.
You can cascade a number of OZD 485 G12 BAS via the
optical interfaces. Devices or bus segments may be
connected to the electrical interfaces of all the cascaded
OZD 485.