Rs-422/V.11 Interface - HEIDENHAIN TNC 415 Technical Manual

2.3 RS-422/V.11 interface

Due to the limited capabilities of the RS-232-C/V.24 interface, the RS-422/V.11 interface was
developed . This interface is also standardized and works symmetrically. The RS-422/V.11 interface
is suitable for data transfer speeds up to 10 Mbit/sec. Since the interface module of the TNC can
only cope with a rate of up to 38,400 baud, a transfer rate of 38,400 baud must also be set at the
RS-422/V.11 interface.
However, at this baud rate it is possible to transmit over a cable one kilometre long.
2.3.1 Hardware
The standard RS-422/V.11 works with differential voltages. The advantage of this method is that, on
the transmission path, radiated interference acts simultaneously and by the same amount on both
signal lines. At the receiver only the differential voltage of the two signal lines is evaluated and
therefore the radiated interference is unimportant.
Considerably longer lines can therefore be used and, because of the suppression of interference, the
transfer speed can be considerably higher.
Physical connections:
Sender
Transmitter
TxD
RxD
01.98 TNC 407/TNC 415/TNC 425
Übertragungsstrecke
Transmission path
2 TNC data interfaces
Empfänger
Receiver
RxD
TxD
8-15