A-B 1747-DCM Direct Communication Module

System Overview

The Direct Communication Module, catalog number 1747-DCM, connects any

SLC 500 programmable controller with expansion chassis or SLC 500 Modular

Programmable Controller to a supervisory Allen-Bradley programmable controller

via the RIO Link, providing a distributed processing system. The 1747-DCM allows

these supervisory processors to transfer data between one another. The 1747-DCM

appears as an RIO adapter to:

• a PLC processor with integral RIO scanner on the RIO Communication Link

• an RIO scanner, catalog number 1771-SN or 1747-SN, on the RIO

Communication Link

The 1747-DCM can physically reside on the RIO Link with any other adapter. It is

compatible with all RIO scanners.

1747-DCM Modules are connected in a daisy-chain configuration using

Belden™ 9463 cable. See the example below.

Extended Node Capability

The 1747-DCM features extended node capability. Extended node capability allows

you to have up to 32 adapters on the RIO link using an 82Ω termination resistor at

both ends of the RIO link for all baud rates.

IMPORTANT Extended node capability can only be used if the scanner and all

adapters on the RIO link have extended node capability.

Hardware Features

DIP Switches

DIP switches enable the 1747-DCM to properly interpret the RIO system addressing.

The 1747-DCM has two banks of DIP switches mounted on its circuit board. Each

bank contains eight switches. The default settings are shown below.

DIP Switch 1 Settings

Chassis Address (SW1-1 through SW1-6)

The chassis address refers to the logical chassis number from the scanner image

that contains a particular 1747-DCM’s image.

The table on the following page shows the settings that define possible chassis

address choices for all scanners. To use this table, first determine which of the

following categories applies to your scanner.

• PLC-2, mini-PLCs, PLC-2/30 with 1770-SD, SD2 remote scanner

• PLC-3 and PLC-5/250 processors (This category includes those with built-in

scanners, as well as the following, without built-in scanners: 1775-54A, -54B,

-S5, SR, -SR5, and 5250-RS.)

• SLC-5/02 (or above) with 1747-SN scanner

After determining which category applies to your 1747-DCM application:

1. Find the column for the scanner used in your application.

2. Go down the column to the chassis address that you assigned to the

1747-DCM.

3. Use the switch settings in the right-most columns of the table that

correspond to your chassis address.