Month: July 2025

Audience

This manual is intended for control engineers and technicians who are

installing, programming, and maintaining a control system that

includes an SLC 500 processor communicating on a DeviceNet

network through a 1747-SDN module.

We assume that you:

• are developing a DeviceNet network by using a SLC 500

processor in conjunction with a 1747–SDN module.

• know each of your device’s I/O parameters and requirements.

• understand SLC processor programming and operation.

• are experienced with the Microsoft Windows environment.

• are familiar with RSNetWorx for DeviceNet software.

The manual contains instructions on configuring a DeviceNet network by using RSLinx and RSNetWorx for DeviceNet software.

It also describes how to use the SLC 500 pass-through feature to communicate with the DeviceNet

network for adjustment and tuning of network devices via an Ethernet and Data Highway Plus (DH+) network.

The example application demonstrates how to perform control on a DeviceNet network by using

an SLC 500 processor and the 1747-SDN module. You use RSLogix 500 programming software to create

a ladder logic program to control a photoeye and a RediSTATION operator interface.

Introduction

This user manual is designed to provide you enough information to get a small example application up and running.

Use this manual if you are knowledgeable about DeviceNet and SLC 500 products,

but may not have used the products in conjunction. The information provided is a base;

modify or expand the examples to suit your particular needs.

The manual contains instructions on configuring a DeviceNet network by using RSLinx and RSNetWorx for DeviceNet software.

It also describes how to use the SLC 500 pass-through feature to communicate with the DeviceNet

network for adjustment and tuning of network devices via an Ethernet and Data Highway Plus (DH+) network.

The example application demonstrates how to perform control on a DeviceNet network by using

an SLC 500 processor and the 1747-SDN module. You use RSLogix 500 programming software to create

a ladder logic program to control a photoeye and a RediSTATION operator interface.

DH–485 Data Link Overview

The DH–485 Data Link is an Allen–Bradley communications network that

supports the transfer of information between programming devices and SLC

processors. The programming device and SLC processor are attached to the

DH–485 Data Link using either an Isolated Coupler or an I/O block. The

DH–485 Data Link may consist of multiple Isolated Couplers and/or I/O

blocks that provide for communication between several programming

devices and/or processors.

The Isolated Couplers and I/O blocks are daisy chained together by a single

twisted pair cable (Belden 9842) to form the DH–485 Data Link. The

programming devices and SLC processors are attached to the Isolated

Coupler or I/O block using Communication Cables (Catalog Numbers

1747–C10 and –C11).

For additional information on the DH–485 Data Link, see the Installation and

Operation Manual for SLC 500 Modular Hardware Style Programmable

Controllers, Publication 1747–804.

DIO Link Overview

The DIO Link is an Allen–Bradley communications network supporting high

speed transfer of control information. A DIO Link consists of a single

master device (the scanner) and multiple slave devices (the I/O blocks). The

scanner and I/O blocks are daisy chained together by a single twisted pair

cable (Belden 9463).

Each I/O block is assigned a I/O block number from 1 to 31 (excluding 16,

which is invalid) by setting the appropriate dip switches on the I/O block.

I/O block numbers must be assigned consecutively. For example, if 5 I/O

blocks are used, they must be assigned I/O block numbers 1 to 5. I/O blocks

do not have to be wired in a contiguous order. For example, I/O block 5 can

follow I/O block 2.

The inputs and outputs for each I/O block are mapped into the words in the

SLC processor’s input and output images. These words correspond to the

scanner’s slot number and the I/O block’s number. For example, if the

scanner is installed in slot 2 of the SLC Rack, I/O block number 1 will have:

• its input data reflected in word 1 of the slot 2 input image

• its output data reflected in word 1 of the slot 2 output image.

The scanner communicates with each I/O block in a round robin fashion.

The scanner initiates communications with an I/O block by first sending its

output data. The I/O block then responds by sending its input data back to

the scanner. After the scanner completes its I/O transfer with the last I/O

block, it begins another transfer with the first I/O block.

DIO System Overview

The DIO system consists of an SLC processor, a scanner, an Isolated Coupler

and I/O blocks. These devices form the DIO System when they are properly

connected to the DIO Link and the DH–485 Data Link as shown below. The

DIO Link and the DH–485 Data Link are independent networks.

The DIO Link consists of the scanner and I/O blocks. It enables the SLC

processor to exchange input and output information with up to 30 I/O blocks.

Output data is transferred from the SLC processor to the scanner, which then

transmits the data to the appropriate I/O block via the DIO Link. The

scanner receives input data from the I/O blocks via the DIO Link. The

scanner then provides this data to the SLC processor. The maximum length

of the DIO Link is 2,500 feet (762 meters) using Belden 9463 cable.

The SLC processor and programming devices communicate using the

DH–485 Data Link. The DH–485 port located on each I/O block allows

remote programming and/or monitoring of the SLC processor. It does not

directly control the I/O block.

Connecting a programming device to any I/O block programming port allows

the programming device to communicate with the SLC processor. The

maximum length of the DH–485 Data Link is 4,000 feet (1,219 meters) using

Belden 9842 cable.

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.

Switchover Conditions

The 1747-BSN module transfers control from the primary to the secondary

processor (switchover) if one of the following fault conditions occurs in the

primary system:

• power failure

• major fault in the processor

• 1747-BSN module fault

• primary processor mode change from Run to Program

Note: In order for switchover to occur, both primary and

secondary modules must be working without faults prior

to the event that triggers the switchover.

Configuration Errors

The module reports the following configuration errors by flashing the fault LED:

• two 1747-BSN modules are configured with the same address

• LSL addresses are not consecutive (addresses must be numbered 0, 1, 2,etc.)

• last LSL switch is not set in the last module in the link

• last LSL switch is set in a module that is not the last in the link, or

• primary and secondary modules do not have the same configuration settings

(secondary module shows the configuration error)

The secondary processor program is not synchronized with the primary program.

The 1747-BSN module provides backup functionality for the following:

• DH+ or RIO on a single pair of modules – Both may be backed up when two

or more pairs of modules are used.

• RS232 – Any RS232 device communicating with channel 0 of the SLC

controller may be backed up provided hardware-handshake lines are not

required. These ports only allow switchover of the transmit, receive and

ground wires for RS232.

Configuration Errors

The module reports the following configuration errors by flashing the fault LED:

• two 1747-BSN modules are configured with the same address

• LSL addresses are not consecutive (addresses must be numbered 0, 1, 2,etc.)

• last LSL switch is not set in the last module in the link

• last LSL switch is set in a module that is not the last in the link, or

• primary and secondary modules do not have the same configuration settings

(secondary module shows the configuration error)