Allen-Bradley SLC 500 Modules – 1746-P3

Technical Dossier

Product Details And Specifications

Allen-Bradley SLC 500 Series Technical Notes

The Evolution of SLC 500 Architecture

The SLC 500 platform was introduced in 1991 as a successor to the SLC 100 and SLC 150 fixed controllers. The architecture is built around the 1747 processor family and the 1746 I/O module family, communicating over a proprietary backplane bus. Early processors such as the 1747-L511 and 1747-L514 offered limited memory (1K–4K words) and supported only DH-485 communications. The mid-generation processors—1747-L541, 1747-L542, 1747-L543—expanded memory to 16K–64K words and introduced support for DF1, DH+, and DeviceNet via the 1747-SDN scanner. The later 1747-L551, 1747-L552, and 1747-L553 processors added EtherNet/IP capability through the 1747-AENTR adapter, bridging the SLC 500 into modern Ethernet-based plant networks. The SLC 500 platform reached end-of-life (EOL) announcement in 2012, with Rockwell Automation recommending migration to the CompactLogix 5370 (1769-L3x) series. Despite EOL status, the SLC 500 remains in active service at thousands of facilities worldwide, creating sustained demand for spare modules, replacement power supplies, and compatible I/O cards.

SLC 500 Full Catalog & Functionalities (SKU List)

The following catalog covers verified SLC 500 series modules, organized by functional category. Each entry represents a discrete, field-replaceable unit (FRU) within the 1746/1747 platform.

Power Supplies

• 1746-P1: 120/240V AC input, 2A/5V DC output, for 4-slot chassis
• 1746-P2: 120/240V AC input, 5A/5V DC output, for 7-slot and 10-slot chassis
• 1746-P3: 120/240V AC input, 3A/5V DC + 0.96A/24V DC, rack-mounting, 4-slot and 7-slot chassis
• 1746-P4: 24V DC input power supply, 5A/5V DC output, for DC-powered installations
• 1746-P5: 120/240V AC input, 10A/5V DC output, for 13-slot chassis
• 1746-P6: 24V DC input, 10A/5V DC output, high-capacity DC supply for 13-slot chassis

Processors (CPU)

• 1747-L541: SLC 5/04 processor, 16K words user memory, DH+/DF1/DH-485 communications
• 1747-L542: SLC 5/04 processor, 32K words user memory, DH+/DF1/DH-485 communications
• 1747-L543: SLC 5/04 processor, 64K words user memory, DH+/DF1/DH-485 communications
• 1747-L551: SLC 5/05 processor, 16K words, EtherNet/IP + DF1/DH-485
• 1747-L552: SLC 5/05 processor, 32K words, EtherNet/IP + DF1/DH-485
• 1747-L553: SLC 5/05 processor, 64K words, EtherNet/IP + DF1/DH-485

Digital Input (DI) Modules

• 1746-IA16: 16-point 120V AC digital input module, screw terminal
• 1746-IB16: 16-point 24V DC digital input module, sinking, screw terminal
• 1746-IV16: 16-point 24V DC digital input module, sourcing (TTL-compatible)

Digital Output (DO) Modules

• 1746-OA16: 16-point 120/240V AC digital output module, triac
• 1746-OB16: 16-point 24V DC digital output module, sourcing, transistor
• 1746-OV16: 16-point 24V DC digital output module, sinking, transistor
• 1746-OW16: 16-point relay output module, 120/240V AC or 24V DC, Form A contacts

Analog Input (AI) Modules

• 1746-NI4: 4-channel analog input, configurable 4–20mA / 0–10V / thermocouple / RTD
• 1746-NI16I: 16-channel analog current input, 4–20mA, high-density

Analog Output (AO) Modules

• 1746-NO4I: 4-channel analog current output, 4–20mA
• 1746-NIO4I: 4-channel combination analog I/O, 2 inputs + 2 outputs, current mode

Specialty / Communications

• 1746-BAS: BASIC module for custom ladder-logic extensions and serial communications
• 1746-HSCE: High-speed counter encoder module, 1MHz input rate, quadrature encoder support
• 1747-SDN: DeviceNet scanner module for SLC 500 rack, supports up to 63 nodes

Sourcing Hard-to-Find & Obsolete SLC 500 Parts

Following Rockwell Automation's EOL declaration, OEM production of SLC 500 modules has ceased. DriveKNMS maintains a dedicated inventory of tested surplus and refurbished SLC 500 modules to support lifecycle extension programs at facilities that cannot justify a full migration to CompactLogix or ControlLogix platforms. Our sourcing network covers North America, Europe, and Asia-Pacific, enabling us to locate low-volume, high-criticality parts such as the 1747-L543, 1746-NI16I, and 1746-HSCE—modules that are no longer available through standard distribution channels. All sourced units are cross-referenced against Rockwell's catalog revision history to ensure firmware and hardware revision compatibility with the target chassis and processor combination.

Quality Control for the SLC 500 Range

SLC 500 modules present specific test challenges due to their backplane-dependent communication architecture. DriveKNMS operates a dedicated SLC 500 test bench comprising a 1746-A10 10-slot chassis, a 1747-L543 reference processor, and calibrated analog signal sources. Each module undergoes the following verification sequence: (1) visual inspection for capacitor bulge, PCB corrosion, and connector pin integrity; (2) backplane communication handshake test confirming correct module ID response; (3) functional I/O verification—all 16 points cycled for digital modules, full-range signal sweep for analog modules; (4) 24-hour burn-in at rated load for power supply modules including the 1746-P3; (5) firmware revision logging and documentation. Modules that fail any stage are quarantined and not returned to inventory.