Linknet – LINK Systems LinkNet I User Manual

Page 9

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LinkNet

2.3

manual rev 2.1 March 25, 1999

Belden 8103 cable and many similar cables

organized as twisted pairs use a special color code
scheme. Instead of each wire using a different color,
each pair uses a color. One wire in the pair is
predominately white with a thin color stripe, and the
other wire in the pair is predominately the color with
a thin white stripe. When referring to these wires a
common convention is to name the predominate
color first. For example, a blue wire with a thin
white stripe is called blue with white (shortened to
blue/white). A white wire with a thin blue stripe is
called white with blue (shortened to white/blue).
This convention will be used in this document.

Other wire types can be used, but assuming

Belden 8103 cable and the Link RS232 to RS485
converter, the network should be wired as shown in
the following sections.

2.1

RS232-RS485 Converter Connections

The Link converter is labeled the same way as

network drop boxes on the RS485 side. The RS232
side is equipped with a 6' cable that plugs into any
standard 9 pin serial port connector on the host
computer. A power cord is also provided. The six
terminal RS485 connector should be wired as
follows:

GND

Green/White and White/Green

RXD+

Orange/White

RXD-

White/Orange

TXD+

Blue/White

TXD-

White/Blue

SHLD

Shield (bare) Wire of Cable

If another kind of RS-232 to RS-485 converter

is used, it should be set up in the following manner:

1) If configurable, transmit should always be

on.

2) TX+ should connect to RXD+ on the drop

box (Orange/White wire).

3) TX- should connect to RXD- on the drop

box (White/Orange wire).

4) RX+ should connect to TXD+ on the drop

box (Blue/White wire).

5) RX- should connect to TXD- on the drop

box (White/Blue wire).

Note that “RX” and “TX” can be called different

things depending on the manufacturer of the
converter, but will almost always reflect some
variation of “transmit” and “receive” (such as TXD
and RXD).

2.2

OmniLink 5000 Connections

There should be 5 connectors on the back of the
OmniLink 5000 operator interface terminal as shown
in Figure 2.2. If only 4 connectors are present, then
an older communications board is installed. If this is
the case, contact Link for pricing to upgrade the unit
to the new communications board with network
support. Appendix “A” has complete instructions for
updating OmniLink 5000 software and retrofitting
the new communications board. Port 5 is the
network port and should be wired as follows:

REF