Selecting A Termination Resistor - Allen-Bradley 1203 Series User Manual

3–2

Installing the Module

Selecting a Termination

Resistor

Artisan Scientific - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisan-scientific.com

Remote I/O Cables

Remote I/O communications modules are connected to Remote I/O

links with twinaxial cable used for Remote I/O and Data Highway

Plus (DH+) communications. When selecting a cable, remember the

following:

•

Only 1770-CD Belden #9463 is tested and approved for RIO and

DH+ installations. Using other cables is at your own risk.

•

The total cable length depends on the baud rate that you are

using. Refer to the following table:

Baud Rate

57.6 K

115.2 K

230.4 K

•

All three of the following conductors must be connected at each

node.

Color

Blue

Shield

Clear

•

Do not use a star topology. Only two cables may be connected at

any wiring point. You can use a series topology and daisy-chain

two wires at a point.

You must terminate both ends of a Remote I/O link to ensure proper

operation. This termination is required only at the ends of the

physical cable. Each Remote I/O link should have exactly two

termination resistors.

If the device that you connect is an end device on the Remote I/O

link, it must be terminated. Refer to the following table to select a

resistor.

Important: You must use an 82 ohm external termination resistor if

the link is operating at 230.4 kbps.

Device

Description

Programmable Controller Refer to its manual.

1336-GM1

Set J2 in position 1-2 for termination and 2-3 for no termination.

Refer to Figure 3.8. The jumper enables a 150 ohm resistor

(Using Jumpers)

1203-GD1, 1203-GK1, or

Connect a resistor between terminals 1 and 2 on the Remote I/O

1336-GM1

connector. Refer to Figure 3.4.

(Using an external termi-

Use an 82 ohm termination resistor unless a device requires a

nation resistor)

150 ohm termination resistor

➀

The following scanners require 150 ohm termination resistors on the RIO link: 1771-SN, 1772-SD,

1772-SD2, 1775-SR, 1775-S4A, 1775-S4B, 6008-SQH1, and 6008-SQH.

The following adapters require a 150 ohm termination resistors on the RIO link: 1771-AS, 1772-ASB

(Series A), 1771-DCM.

The following devices require a 150 ohm termination resistors on the RIO link: 1771-AF.

Maximum Length

3,048 m (10,000 ft)

1524 m (5,000 ft)

762 m (2,500 ft)

Description

1

SH

2

➀

.

➀

.