Allen-Bradley 1747-ASB Remote I/O Adapter Module for SLC 500

Overview

The Allen-Bradley 1747-ASB Remote I/O Adapter Module is an I/O communication module from the SLC 500 family, engineered to provide a communication channel between an I/O scanner and the chassis it controls. In distributed control installations, the adapter lets a SLC 500 processor in one chassis communicate with I/O in remote chassis, so plant engineers can spread field I/O across a machine or process while keeping the control logic in one location. As an OEM-qualified spare, the 1747-ASB is an essential item in the spares inventory of any facility running SLC 500 control systems.

Engineering Design

The Allen-Bradley 1747-ASB is a single-slot module that installs directly into the backplane of a SLC 500 chassis. It operates as an adapter on the Remote I/O network: the adapter sits in the remote chassis, while a scanner module in the processor chassis controls the network. When the module is installed and addressed correctly, the processor is able to read inputs from and write outputs to the remote chassis as if the I/O were local, which simplifies both programming and troubleshooting. The module is a drop-in replacement for existing installations, and because Rockwell Automation requires no user program logic for the adapter itself, a tested spare can be fitted and returned to service using only its DIP switch configuration.

Key Features

• Remote I/O adapter module from the Allen-Bradley SLC 500 family
• Provides the communication channel between an I/O scanner and remote I/O chassis
• Single-slot backplane installation for fast field replacement
• Supported by Allen-Bradley SLC 500 documentation and programming tools
• Sourced as genuine, tested spares for legacy installed-base support

Industrial Applications

• SLC 500 control systems with distributed field I/O
• Machine and process lines where remote chassis are mounted close to field devices
• Oil and gas, water, power and general manufacturing plants in Oman and the GCC
• Upgrade and repair programmes for legacy Allen-Bradley installations

Technical Specifications

Why Seven Star LLC

Seven Star LLC supplies genuine and tested Allen-Bradley automation spares to industrial customers across Oman and the wider GCC region. Every Allen-Bradley 1747-ASB we supply is checked and matched against the catalog number before dispatch, and our team helps you confirm compatibility with your SLC 500 installation before you order. Where an exact match is not available, we source it on request rather than offering substitutes without approval.

FAQ

Compatibility & Integration

The 1747-ASB is part of the Allen-Bradley SLC 500 family, and it is designed to work with the SLC 500 chassis, processors and programming tools used throughout that family. Because the module appears to the processor as a standard backplane device, no special programming is required beyond the normal configuration of the Remote I/O network, which keeps commissioning time short when the module is installed in an existing system.

When replacing an adapter in a running plant, the maintenance team simply removes the failed module, installs the spare into the same slot and restores the network address. The module works with the same documentation, spare parts and engineering practices that already exist in plants operating SLC 500 systems, which is why the 1747-ASB remains one of the most requested remote I/O spares for legacy Allen-Bradley installed base.

Installation and Chassis Addressing

The Allen-Bradley 1747-ASB must be installed in slot 0 — the leftmost slot — of a 1746 remote chassis, the position an SLC processor would normally occupy. From there the module behaves as an adapter, or slave, on the Remote I/O link and simultaneously as the master of the remote chassis and of any optional remote expansion chassis connected to it, mapping the image of the installed 1746 I/O modules directly into the SLC or PLC processor image table. A single 1747-ASB is capable of controlling 30 slots; remote chassis and remote expansion chassis slots are numbered from 0 to 30, and slots numbered 31 and above cannot be addressed by the adapter.

Configuration is carried out entirely through the module DIP switches: starting logical rack and group number within the scanner image, Remote I/O baud rate, primary or complementary chassis selection, and adapter image size in two-logical-group increments from 2 to 32 groups. Further switches select the addressing mode (2-slot, 1-slot or 1/2-slot), discrete or block transfer mapping of specialty I/O, Hold Last State behaviour for discrete outputs if the link is lost, Processor Restart Lockout, and I/O module keying against the configuration saved in non-volatile memory. No user program logic is required for the adapter itself.

Remote I/O Link Data

Link baud rate determines both the maximum cable distance and the terminating resistor size. Over Belden 9463 twinaxial cable the 1747-ASB supports 57.6K baud to 3048 m (10,000 ft), 115.2K baud to 1524 m (5000 ft) and 230.4K baud to 762 m (2500 ft), with the same rate set on every adapter on the link. Where the scanner and all adapters have extended node capability the terminating resistor is 82 Ω 1/2 W at every rate; where they do not, 150 Ω 1/2 W is used at 57.6K and 115.2K baud and 82 Ω at 230.4K baud. Extended node capability also raises the number of devices the link will carry from 16 to 32, which matters on large distributed SLC 500 systems in Omani plants where a single scanner serves many remote chassis.

Electrically the module draws 375 mA at 5V DC from the chassis backplane, a figure that must be included when sizing the remote chassis power supply. It operates from 0 to 60 °C, withstands 30 G operating shock, and carries UL, CSA, Class I Division 2 Groups A, B, C and D, CE, Marine and C-Tick approvals, suiting the classified electrical rooms common in refinery and gas plant installations across Oman and the GCC.

Ordering Information

To order the Allen-Bradley 1747-ASB from Seven Star LLC, quote the catalog number 1747-ASB together with the quantity you require. Our team confirms availability, pricing and delivery to your site in Oman or anywhere in the GCC. We can also advise on the matching 1747-SN scanner, chassis and Belden 9463 Remote I/O cabling where a complete link is being restored rather than a single module replaced.

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