HSLink Introduction
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15
Ø
RS422 with Multi-drop
Typical RS422 is not actually a networking spec. We do make some change.
The TXD of master is connected to RXD of every slave I/O modules. And all
TXD of slaves are connected to RXD of master. Only master use TXD(of
master)
à
RXD(of slave) channel, and ,by well designed, only one slave at
one time sends message with TXD(of slave)
à
RXD(of master) channel. So,
there could be 63 slave I/O modules in a set of HSLink network. This kind of
networking solution is called
RS422 with Multi-drop
.
Ø
Circuit
Every HSLink master can support 2 circuit loops. Inside the two circuits, the
TXD(of master)
à
RXD(of slave) channels are actually of the same signal
sent by master, but the TXD(of slave)
à
RXD(of master) channels are not
that case. TXD(of slave)
à
RXD(of master) channels are isolated from each
circuit, and signals inside wouldn’t pass through master from one circuit to
the other.
As the sketch map below showed:
Figure 1.13: HSLink wiring – RS422 with multi-drop
l
There are two RJ45 notches in each master. Each notch supports one
circuit of wiring.
l
Only 4 of 100BaseTX cable’s 8 lines are used.
l
All slave modules are parallel connected.
l
With isolation between connection cable and individual slave I/O
module, signal is well protected from being interfered by any other
slaves.
1
2
3
4
5
6
7
8
RJ45
1
2
3
4
5
6
7
8
RJ45
TXD
RXD
Controller
MASTER 0
MASTER 1
RJ45
TXD RXD
Slave I/O module
RJ45
TXD RXD
Slave I/O module
RXD
TXD
Slave I/O module
RJ45
RXD
TXD
Slave I/O module
RJ45
RXD
TXD
Slave I/O module
RJ45
