
1–6 Network Layers
Publication
17706.5.16 - October 1996
DH485 Link
A DH485 link is a low cost, peer-to-peer programming and
data-acquisition link for a variety of Allen-Bradley products.
DH485 topology is similar to DH and DH+ topology. You can
connect as many as 32 nodes to a DH485 link.
The DH485 link is based on the Electrical Industries Association
(EIA) Standard RS-485 Electrical Signalling Specification.
A variety of Allen-Bradley products (including SLC 500 controllers,
1784-KTX, 1747-KE, 1770-KF3, and operator interface devices) act
as token-passing masters on the DH485 link. This link also supports
a respond-only mode for low-level devices on the link, such as
Allen-Bradley bar code decoders.
A DH485 link implements peer-to-peer communication with a
token-passing scheme to rotate link mastership among the nodes
connected to that link.
DH485 link
T53 programming terminal with a
1784KTX card installed and running
6200 series software
PLC5 processor
SLC 5/04
processor
notebook compute
with 1784PCMK
1747AIC
RS232/RS485
converter
1747AIC
1747PIC
À
channel 0
channel 1
DH+ link
DTAM Plus
operator
interface
1747AIC
PanelV
iew 550
operator terminal
1770KF3
1747AIC
SLC 5/01 processor
in 17slot modular system
SLC 5/03
processor
to remote
I/O chassis
remote I/O link
À
T
o connect an SLC 5/04 to a 1747PIC,
use a 9pin (male) to 25pin (female) adapter.
1747SN
1747AIC
SLC 500
fixed 30I/O
controller with
expansion chassis
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