ADLINK HSL-AI16AO2-M-VV/-AV - Manual (Page 35)

22 Introducing HSL
1.4.4 Wiring
The HSL network follows a modified RS-422 electrical specifica-
tion.
Wiring
The wire cables of an HSL system are carefully selected for
installation convenience and standardization without sacrificing
communication quality. A 100BaseTX cable with RJ-45 con-
nectors is used on HSL systems.
Full-duplex RS-422 with multi-drop
The typical RS-422 is not a networking specification. However,
HSL modified the specification to suit network applications. The
TXD of the master is connected to the RXD of every slave I/O
modules, while all TXD of slaves are connected to the RXD of
the master. Only the master uses TXD (of master) to RXD (of
slave) channel. Through design, only one slave at a time sends
message with TXD (of slave) to RXD (of master) channel. This
kind of networking solution is called RS-422 with multi-drop.
Ports
An HSL master supports a 2-port segment. Inside the ports, the
TXD (of master) to RXD (of slave) channels are of the same
signal sent by master. In contrast, the TXD (of slave) to RXD
(of master) channels are isolated from each circuit and signals
inside do not pass through the master from one circuit to
another.