Allen-Bradley 1747-ASB Remote I/O Adapter Module

The Allen-Bradley 1747-ASB, also cataloged as the 1747-ASB Remote I/O Adapter Module, operates as a dedicated hardware component for remote I/O link arbitration and chassis-level device coordination within SLC 500 RIO network structures.

Suffix Breakdown & Model Matrix

The 1747-ASB designation is a single-field catalog number with no defined functional suffix segmentation. All operational behaviors are embedded within the base module firmware and chassis configuration.

Hardware Specifications

Remote I/O Arbitration and Bus Role Execution

The module implements SLC 500 Remote I/O (RIO) protocol handling with cyclic scan-based data exchange between master scanner and remote chassis. Slot 0 positioning defines backplane arbitration priority and establishes chassis identity on the RIO segment. The adapter manages dual-role operation, allowing both slave-side I/O mapping and master-side chassis coordination depending on system topology. Communication timing is synchronized to selectable baud rates (57.6, 115, 230 kbit/s), affecting scan window allocation and update latency across the RIO link.

Frequently Asked Questions

Q: Does the 1747-ASB require user-level programming for operation?
A: No. The module operates through hardware configuration and DIP switch settings; no application-level programming is required.

Q: Can the module function in both master and slave configurations simultaneously?
A: Yes. The architecture supports dual-mode operation depending on chassis role and RIO network topology definition.

Q: What is the impact of backplane current draw on chassis sizing?
A: The module consumes 375 mA at 5 VDC from the backplane, which must be included in total chassis power budget calculation to prevent slot undervoltage conditions.

Field Installation Guidelines

• Install the module exclusively in Slot 0 of a compatible 1746 remote chassis.

• Verify RIO network baud rate selection before power application.

• Maintain proper grounding of chassis to reduce communication reference drift on long RIO segments.

• Use shielded twisted pair cable for RIO communication trunk wiring.

• Ensure DIP switch configuration matches master scanner addressing scheme prior to commissioning.

• Avoid routing RIO cables parallel to high-noise switching conductors or motor drive lines.