Is Your Legacy SLC 500 RIO Link Still Running Without a Spare?
When a remote I/O adapter fails, an entire production line can stop within seconds. The Allen-Bradley 1747-ASB is a Universal Remote I/O adapter module that places a remote SLC 500 chassis onto an RIO link. It acts as a slave to a scanner while serving as the local backplane master for the remote rack. This module occupies slot 0 of a 1746 remote chassis and maps I/O images with no user programming.
Because Rockwell Automation discontinued this module on November 1, 2013, with no planned replacement, sourcing a verified unit is now a critical maintenance decision. SpareTechPLC helps you confirm availability before your next downtime event.
What Makes the 1747-ASB a Reliable RIO Adapter?
The 1747-ASB belongs to the SLC 500 / Bulletin 1747 family. It installs in slot 0 of a remote 1746 chassis, where it controls up to 30 chassis slots. The module supports baud rates of 57.6, 115.2, and 230.4 kbaud. At 57.6 kbaud, the maximum distance reaches 3040 m. This range lets you distribute I/O across large facilities without long field-wire runs.
Configuration happens through DIP switches for logical rack/group, baud rate, image size (2-32 logical groups), addressing mode, and restart behavior. Three seven-segment displays plus COMM and FAULT LEDs give you immediate visual status. The module draws 375 mA at 5V DC from the backplane. It uses Belden 9463 cable with 82/150 Ω termination and supports extended-node capability.
Key Technical Specifications
| Specification | Value |
|---|---|
| Product Type | Remote I/O Adapter Module |
| Series | SLC 500 / Bulletin 1747 |
| Backplane Current | 375 mA @ 5V DC |
| Baud Rates | 57.6 / 115.2 / 230.4 kbaud |
| Max Distance | 3040 m @ 57.6 kbaud |
| Chassis Slots Controlled | Up to 30 |
| Image Size | 2-32 logical groups |
| Cable | Belden 9463 (82/150 Ω termination) |
| Operating Temperature | 0 to 60 C |
| Discontinuation Date | 2013-11-01 |
Replacement and Upgrade Path for Discontinued RIO Adapters
Rockwell Automation lists no planned replacement for the 1747-ASB. The official migration path points to the 1747-AENTR (EtherNet/IP) or other gateways. That means your upgrade decision depends on how much of your existing SLC 500 infrastructure you plan to keep.
If you maintain a mixed legacy system, keeping verified 1747-ASB units in stock protects your RIO link. If you plan a phased migration, the 1747-AENTR moves your remote chassis onto EtherNet/IP while preserving your 1746 I/O modules. Either path requires careful planning because the 1747-ASB is not hot-swappable. You must never install, remove, or wire it with power applied.
When to Repair vs. Replace
- Repair: Your RIO link uses multiple remote chassis and your scanner remains in service.
- Replace: You are already migrating to EtherNet/IP and want to reduce long-term spares.
- Hybrid: Keep one verified spare while you stage a gateway migration.
Installation and Setup Essentials
Mount the 1747-ASB in slot 0 of a remote 1746 chassis. Slot 0 is reserved for the processor or the 1747-ASB adapter. The 1746 chassis backplane supplies 5.1V DC @ 10A and 24V DC @ 2.88A to all modules. Field-side load power requires an external supply.
Set the DIP switches before applying power. Match the baud rate, logical rack/group, image size, addressing mode, and restart behavior to your scanner configuration. Use Belden 9463 cable with proper 82/150 Ω termination. Removable terminal blocks simplify field wiring, and Bulletin 1492 pre-wired interface cables are available for faster installation.
Always follow the manufacturer’s safety manual. Do not install, remove, or wire the module with power applied.
Maintenance and Reliability for Legacy SLC 500 Systems
Inspect the module periodically for loose terminal connections, LED status, and seven-segment display codes. Keep the enclosure within 0 to 60 C and 5-95% RH non-condensing. Dust and vibration are common wear factors in industrial cabinets.
Because the 1747-ASB is discontinued, every spare unit becomes more valuable over time. A single verified spare can prevent hours of unplanned downtime. That is the strongest ROI argument for keeping one on the shelf while you plan your migration.
Compatibility and Integration
The 1747-ASB works as a slave on an RIO link and as a master on the remote chassis backplane. It integrates with SLC 500 systems and 1746 chassis models including the 1746-A4, -A7, -A10, and -A13. All chassis are panel-mount. The module maps I/O images without user programming, which simplifies integration with existing scanners.
If you operate multiple remote racks, the extended-node capability and 3040 m distance at 57.6 kbaud give you flexible network design. Verify your scanner supports the selected baud rate and image size before commissioning.
Selection Guide: What to Verify Before You Buy
Before purchasing a 1747-ASB, confirm the lifecycle status and availability with SpareTechPLC. Ask about the module’s physical condition, DIP switch settings, and any signs of prior field use. Verify that your chassis model and slot 0 assignment match the module’s requirements.
Check your cable type and termination. Belden 9463 with 82/150 Ω termination is required. Confirm your scanner configuration supports the baud rate and image size you plan to use. If you are migrating, ask about the 1747-AENTR as an alternative path.
SpareTechPLC specializes in industrial automation parts and can help you source verified legacy modules. Contact them to confirm current availability before your next maintenance window.
Frequently Asked Questions
Is the 1747-ASB still available from Rockwell Automation?
No. Rockwell Automation discontinued the 1747-ASB on November 1, 2013, with no planned replacement. Contact SpareTechPLC to verify current availability.
What replaces the 1747-ASB in a new system?
Rockwell recommends migrating to the 1747-AENTR (EtherNet/IP) or other gateways. This moves your remote chassis onto EtherNet/IP while preserving 1746 I/O modules.
Can I hot-swap the 1747-ASB?
No. The module is not hot-swappable. Do not install, remove, or wire it with power applied. Always follow the manufacturer’s safety manual.
What cable does the 1747-ASB require?
Use Belden 9463 cable with 82/150 Ω termination. Match the baud rate and image size to your scanner configuration.
How many chassis slots can the 1747-ASB control?
The module controls up to 30 chassis slots and supports image sizes from 2 to 32 logical groups.
