Link design, Link design -2 – Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers User Manual

Page 134

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Publication 1785-UM012D-EN-P - July 2005

9-2 Communicating with Devices on a DH+ Link

Devices that You Can Connect

Link Design

Specify 1770-CD (Belden 9463) cable. Connect a DH+ network using a daisy
chain or trunk line/drop line configuration.

Verify that your system’s design plans specify cable lengths within allowable
measurements.

For daisy chain configurations, use this table to determine the total cable
length you can use.

Product

Catalog
Number

Application

Required
Cables

ControlLogix Data Highway Plus Remote I/O
Interface Module

1756-DHRIO

Allows communication between PLC-5 controllers over
different networks, such as Data Highway Plus,
ControlNet and Ethernet

1770-CD

Data Highway or Data Highway Plus
(RS-232C or RS-422-A) Interface Module

1770-KF2

Connects an asynchronous (RS-232C) device to a Data
Highway or DH+ network

1770-CD

Data Highway / Data Highway Plus
on Broadband

1771-KRF

Media bridge connecting as many as 18 Data Highway
networks to communicate over a facility-wide broadband
cable system

Communication Interface Card

1784-KL

Connects the T47 Portable Programming Terminal to DH+ 1784-CP

1784-CP2
1784-CP3
1784-CP5
1784-CP6

Data Highway Plus XT/AT Interface Module 1784-KT

Connects IBM XT or AT compatible computers to DH+

Data Highway Plus PS/2 Interface Module

1784-KT2

Connects IBM PS/2 compatible computers to DH+

Data Highway Plus to Data Highway
Interface Module

1785-KA

Connects a Data Highway network to a DH+ network

1770-CD

DH+ to DH-485 Interface Module

1785-KA5

Connects a DH-485 link to a DH+ link.

Data Highway Plus RS-232C Interface
Module

1785-KE

Connects an asynchronous (RS-232C) device and DH+

PCMCIA Card

1785-PCMK

Connects PCMCIA Bus notebook computers to DH+

1784-PCM5

IMPORTANT

The maximum cable length for DH+ depends on the
transmission rate. Configure all devices on a DH+ link to
communicate at the same transmission rate.

Trunk line/drop line considerations:
When using a trunk line/drop line configuration,
use 1770-SC station connectors and follow these
cable-length guidelines:
• trunk line-cable length – depends on the

communication rate of the link

• drop-cable length – 30.4 m (100 cable-ft)
For more information about designing trunk
line/drop line configurations, see the Data
Highway Plus/Data Highway II/Data Highway-485
Cable Installation Manual
, publication 1770-6.2.2.

A DH+ link using this
communication rate

Cannot exceed this
cable length

57.6 kbps

3,048 m (10,000 ft)

115.2 kbps

1,524 m (5,000 ft)

230.4 kbps

762 m (2,500 ft)

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