Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual - Manual (Page 221)

221 Publication 1747-UM011G-EN-P - June 2008
Appendix
D
Setting Up the DH+ Network
This appendix provides an overview of the Data Highway Plus (DH + )
communication protocol and explains how the SLC 5/04 processors support
it. This appendix also provides:
• a DH + communication protocol overview.
• an SLC 5/04 processor and DH + communication.
• wiring connectors for DH + communication for SLC 5/04.
• a typical DH + network configuration.
Data Highway Plus
Communication Protocol
Overview Data Highway Plus implements peer-to-peer communication with a
token-passing scheme to rotate link mastership among a maximum of 64
nodes. Since this method does not require polling, it helps provide
time-efficient reliable data transport. The DH
+ features:
• remote programming of PLC-2, PLC-3, PLC-5 and SLC 500 processors
on your network.
• direct connections to PLC-5 processors and industrial programming
terminals.
• easy re-configuration and expansion if you want to add more nodes
later.
• a communication rate of 57.6 Kbaud, 115.2 Kbaud, or
230.4 Kbaud.
The following table summarizes the type of termination resistor needed to
communicate at the specified communication rate with the maximum cable
length.
Termination Resistor and Communication Link
Termination Link Resistor
Value
Ω
Communication Rate
(Kbaud) Maximum Cable Length
m (ft)
150 57.6 3048 (10,000)
150 115 1542 (5000)
82 230.4 762 (2500)