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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.

Overview

The 1747-BSN Backup Scanner Module provides a high-speed communication

channel between two modular SLC 500™ (5/02 or higher) processors. The 1747-

BSN backup system uses a set of modules, with one or more 1747-BSN modules

residing in the primary system and one or more complementary modules in the

secondary or backup system. The primary system controls the operation of

remote I/O, while the secondary system monitors communications via the highspeed

serial link (HSSL) and is available to take over control in the event of a

fault in the primary system.

The backup scanner has the capability to switch between two communication

channels. The first channel is configurable as Remote I/O (RIO) or Data

Highway Plus™ (DH+). The second channel is used to switch one RS232/485

channel in order to provide connection for electronic operator interfaces.

A backup system using the 1747-BSN modules supports up to eight BSN

modules in each processor chassis, connected by a local status link (LSL). Only I/

O residing in remote chassis is backed up. Local I/O is not backed up. Examples

of RIO and DH+ system configurations are shown in Figures 1 and 2 on page 6.

Note: During the transfer of control from one processor to

another (switchover), the output modules in the remote

chassis maintain their last state until the secondary

processor program takes control.

Configuration Parameters

The DIP switches allow you to configure the following items:

• Starting Logical Rack Number (Logical Rack) – is the 1747-ASB module’s

starting logical rack number in the scanner’s image.

• Starting Logical Group Number (Logical Group) – is the 1747-ASB

module’s starting logical group number within the scanner’s image.

• Baud Rate (Baud Rate) – is the 1747-ASB module’s RIO link communication

rate. The baud rate must be the same for all adapters on the RIO link.

• Primary/Complementary SLC Chassis (PRI/COMP) – determines

whether the 1747-ASB module appears to the scanner as a primary or

complementary chassis.

• Adapter Image Size (IMAGE SIZE) – indicates the I/O image size to be

reserved for the adapter. It can be any size between 2 and 32 groups in

2 logical group increments.

• Hold Last State (HLS) – determines whether the discrete output modules

are held in their last state when:

– RIO link communication with the 1747-ASB module is lost.

– The scanner inhibits the 1747-ASB module.

– The scanner sends Reset, Adapter Decide commands to the 1747-ASB module.

• Processor Restart Lockout (PRL) – determines whether the 1747-ASB

module automatically resumes RIO link communications if communication is

lost and then restored.

• Link Response Time (RESP) – selects restricted or unrestricted RIO link

response time.

• Last Chassis/PLC-3 Backup (LAST CHA) – When the 1747-ASB module is

used with a PLC-2 or PLC-5, this switch indicates to the scanner that the

1747-ASB module is the last adapter mapped into the 1747-ASB module’s

highest logical rack. When using a PLC-3 processor, the switch determines

whether the 1747-ASB module supports the PLC-3 backup function.

• Addressing Mode (ADDR MODE) – determines the 1747-ASB module’s

remote chassis and remote expansion chassis addressing mode. 2-slot,

1-slot, and 1/2-slot are available.

• Specialty I/O Mode (SP MODE) – determines whether the 1747-ASB

module discretely maps or block transfer maps specialty I/O modules in its

remote chassis and remote expansion chassis.

• I/O Module Keying (KEY) – determines if the 1747-ASB module saves its

current I/O module and DIP switch configuration to its non-volatile memory,

or if the 1747-ASB module compares the current I/O module and DIP switch

configuration to the one saved in its non-volatile memory.

1747-ASB Module Overview

The 1747-ASB module is an SLC 500 single-slot, RIO communication link module. It

occupies the first slot (slot 0) of a 1746 remote chassis, where the SLC processor

normally resides.

The 1747-ASB module is an adapter, or slave, on the RIO link, and the master of the

remote chassis and remote expansion chassis in which it is installed. Remote

expansion chassis are optional. The module acts as a gateway between the scanner

and the I/O modules residing in the remote chassis and remote expansion chassis.

It maps the image of the I/O modules in its remote chassis and remote expansion

chassis directly to the SLC or PLC processor image.

Output data is sent from the scanner of either the SLC or PLC local chassis to the

1747-ASB module across the RIO link. This data is automatically transferred to the

output modules across the chassis backplane by the 1747-ASB module. Inputs from

the input modules are collected via the backplane by the 1747-ASB module and

sent back to the scanner across the RIO link. No user programming of the 1747-ASB

module is necessary.

The adapter reads the network address switches first to determine if the

switches are set to a valid number. You set the node address by using the

network address switches. Valid settings range from 001…254.

When the switches are set to a valid number, the adapter’s IP address is

192.168.1.xxx (where xxx represents the number set on the switches).

The adapter’s subnet mask is 255.255.255.0 and the gateway address is set to

0.0.0.0. The adapter does not have a host name assigned, or use any Domain

Name System when using the network address switch settings.

If the switches are set to an invalid number (for example, 000 or a value greater

than 254 excluding 888), the adapter checks to see if DHCP is enabled. Setting

the switches to 888 restores default factory settings.

IMPORTANT If you set the value of the adapter switch to 888 and then power cycle

the module, the following occurs:

• The DHCP Enabled function is enabled (set to True).

• The Ethernet link is negotiated automatically. The Auto Negotiate

function is set to True.

• The web server is enabled. The Disabled Web Server function is

disabled.

• The Ethernet ports are disabled. Both ports are re-enabled once the

switches are returned to their previous value and power is cycled.

Diagnostic Indicators The module has the following diagnostic indicators:

• Link 1 and Link 2 status indicator

• Module indicator

• 4-character status display

What the Adapter Does The 1747-AENTR EtherNet/IP adapter performs the following primary tasks:

• Control of real-time I/O data (also known as implicit messaging) – the

adapter serves as a bridge between I/O modules and the network

• Support of messaging data for configuration and programming

information (also known as explicit messaging)

Use of the Common

Industrial Protocol (CIP)

The adapter uses the Common Industrial Protocol (CIP), the application layer

protocol specified for EtherNet/IP, the Ethernet Industrial Protocol. It is a

message-based protocol that implements a relative path to send a message

from the producing device in a system to the consuming devices.

The producing device contains the path information that steers the message

along the proper route to reach its consumers. Since the producing device

holds this information, other devices along the path simply pass this

information; they do not store it.

This has the following significant benefits:

• You do not need to configure routing tables in the bridging modules,

which greatly simplifies maintenance and module replacement.

• You maintain full control over the route taken by each message, which

enables you to select alternative paths for the same end device.