Allen-Bradley 1747-L551/B SLC 5/05 Processor Module

The Allen-Bradley 1747-L551/B, also cataloged as the 1747-L551/B SLC 5/05 processor module, operates as a dedicated CPU execution unit for scan-based logic processing and Ethernet-enabled I/O image management within SLC 500 backplane controller systems.

Configured for Ethernet-based cyclic control execution across SLC 5/05 architectures, the Allen-Bradley 1747-L551/B (1747-L551/B CPU processor module) provides deterministic instruction processing with 64K-word memory and TCP/IP communication integration for distributed industrial control networks.

Suffix Breakdown & Model Matrix

The suffix “/B” denotes a hardware revision within the 1747-L551 SLC 5/05 family. No functional partition or architectural variation is defined in the provided dataset. Core execution behavior, memory mapping, and Ethernet stack implementation remain consistent with SLC 5/05 baseline design.

Hardware Specifications

Ethernet Backplane Communication & I/O Deterministic Mapping

Within the Rockwell Automation SLC 500 architecture, the 1747-L551/B executes cyclic scan processing while maintaining synchronized backplane I/O image tables and Ethernet-based communication channels. The processor integrates TCP/IP stack execution over Ethernet, enabling remote access to program memory, diagnostics, and distributed control data.

Backplane bus communication is executed in deterministic scan cycles (~0.9 ms/K instruction typical), where 64K-word memory is processed sequentially through instruction execution logic. Ethernet and RS-232 channels operate in parallel, separating local programming traffic from plant-level data exchange.

I/O density scaling supports up to 8192 digital and 480 analog points across 3 chassis / 30 slots, with centralized image table synchronization ensuring deterministic update consistency across expansion racks and remote I/O nodes.

Frequently Asked Questions (FAQ)

Q: Does the 1747-L551/B support Ethernet programming and monitoring simultaneously with control execution?
A: Yes. Ethernet TCP/IP communication operates independently of scan execution and does not interrupt cyclic logic processing.

Q: Can the processor operate across multiple chassis configurations?
A: Yes. The system supports up to 3 chassis or 30 slots with centralized I/O image table synchronization.

Q: Is hot-swapping supported for the CPU module?
A: No. CPU replacement requires full system power removal to maintain backplane integrity and memory consistency.

Field Installation Guidelines

• Install CPU module into SLC 500 chassis slot with full backplane connector engagement.

• Ensure chassis power is isolated before installation or removal of processor module.

• Maintain shielded separation between Ethernet/RS-232 cables and high-voltage field wiring.

• Verify IP addressing and communication configuration before network commissioning.

• Maintain proper chassis grounding to stabilize backplane reference potential.

• Confirm Flash EEPROM program integrity prior to startup sequence.