Allen-Bradley SLC 500 Modules – 1747-CP3

Technical Dossier

Product Details And Specifications

Allen-Bradley SLC 500 Series Technical Notes

The Allen-Bradley SLC 500 (Small Logic Controller 500) is a modular, rack-based programmable logic controller platform introduced by Rockwell Automation in the late 1980s. It has achieved widespread deployment across global heavy industry sectors including petrochemical refineries, nuclear power auxiliary systems, pulp and paper mills, automotive assembly lines, and water treatment facilities. The SLC 500 platform operates on a fixed or modular chassis architecture, supporting a broad range of I/O, communication, and specialty modules. Its installed base remains one of the largest of any mid-range PLC platform globally, with millions of units still in active service as of 2026.

The Evolution of SLC 500 Architecture

The SLC 500 platform was launched with the fixed-hardware SLC 5/01 and SLC 5/02 processors, which offered DH-485 network connectivity and limited memory. The SLC 5/03 introduced RS-232 and DH-485 dual-port communication, expanding integration capability. The SLC 5/04 added Data Highway Plus (DH+) as the primary backplane communication bus, enabling peer-to-peer messaging across larger plant networks. The SLC 5/05 represented the final major processor revision, incorporating native Ethernet/IP (10/100 Mbps) connectivity and expanded memory up to 64K words.

The 1747 series defines the SLC 500 chassis, power supplies, and processor modules, while the 1746 series covers the I/O and specialty modules. Programming is performed via RSLogix 500 software (legacy) or Studio 5000 Logix Designer in compatibility mode. The platform uses a proprietary backplane bus that is not compatible with ControlLogix or CompactLogix architectures, making direct migration non-trivial and sustaining long-term demand for original SLC 500 spare parts.

As of 2026, the SLC 500 platform is classified by Rockwell Automation as End of Life (EOL) / Discontinued. No new production runs are planned. This classification elevates the strategic importance of aftermarket sourcing partners capable of supplying tested, certified replacement modules.

SLC 500 Full Catalog & Functionalities (SKU List)

Processors & CPU Modules

• 1747-L511: SLC 5/01 processor, 1K memory, DH-485 port, fixed I/O controller.
• 1747-L514: SLC 5/01 processor, 4K memory, DH-485 port, expanded program capacity.
• 1747-L524: SLC 5/02 processor, 4K memory, DH-485, supports up to 4096 I/O points.
• 1747-L531: SLC 5/03 processor, 8K memory, dual RS-232/DH-485 ports.
• 1747-L532: SLC 5/03 processor, 16K memory, dual-port communication.
• 1747-L541: SLC 5/04 processor, 16K memory, DH+ and DH-485 ports.
• 1747-L542: SLC 5/04 processor, 32K memory, DH+ network primary node.
• 1747-L543: SLC 5/04 processor, 64K memory, high-capacity DH+ controller.
• 1747-L551: SLC 5/05 processor, 16K memory, Ethernet/IP and DH-485 ports.
• 1747-L552: SLC 5/05 processor, 32K memory, dual Ethernet/IP and DH-485.
• 1747-L553: SLC 5/05 processor, 64K memory, full Ethernet/IP integration.

Programming Cables & Communication Accessories

• 1747-CP3: RS-232 to DH-485 programming cable, connects PC serial port to SLC 500 processor channel 0. Compatible with SLC 5/03, 5/04, 5/05. Required for RSLogix 500 offline/online programming sessions.
• 1747-UIC: USB-to-DH-485 interface converter, USB Type-A to SLC 500 channel 0, replaces 1747-CP3 on modern PCs without RS-232 ports.
• 1747-PIC: Personal Interface Converter, RS-232 to DH-485, earlier generation predecessor to 1747-CP3.

Digital Input (DI) Modules — 1746 Series

• 1746-IA16: 16-point 120VAC digital input module, screw terminal, standard industrial AC input.
• 1746-IB16: 16-point 24VDC digital input module, sink/source configurable.
• 1746-IB32: 32-point 24VDC digital input, high-density rack module.

Digital Output (DO) Modules — 1746 Series

• 1746-OA16: 16-point 120/240VAC digital output, triac output, zero-cross switching.
• 1746-OB16: 16-point 24VDC digital output, transistor sink type.
• 1746-OW16: 16-point relay output module, Form C contacts, 240VAC/24VDC rated.

Analog I/O Modules — 1746 Series

• 1746-NI4: 4-channel analog input, 4–20mA / 0–10VDC selectable, 12-bit resolution.
• 1746-NO4I: 4-channel analog current output, 4–20mA, 12-bit resolution.

Power Supply Modules — 1746 Series

• 1746-P1: 2A power supply, 120/240VAC input, for 4-slot chassis.
• 1746-P2: 5A power supply, 120/240VAC input, for 7/10/13-slot chassis.
• 1746-P4: 10A power supply, 120/240VAC input, high-load chassis configurations.

Communication Adapter Modules

• 1747-SDN: DeviceNet scanner module, master node, supports up to 64 DeviceNet slave devices.
• 1747-SN: Remote I/O scanner module, DH+ compatible, links remote I/O racks.
• 1747-ASB: Adapter module for remote I/O, slave mode, connects remote chassis to DH+ network.

Quality Control for the SLC 500 Range

SLC 500 modules present specific test challenges due to their proprietary DH-485 and DH+ backplane communication protocols. DriveKNMS applies the following verification procedures to all SLC 500 inventory:

• Backplane continuity and bus termination resistance check on all 1746-series I/O modules.
• Processor firmware version identification and memory integrity test using RSLogix 500 v12.x.
• DH-485 communication loop test for all processor channel 0 ports, including 1747-CP3 cable continuity verification.
• DH+ token-passing network simulation for SLC 5/04 processors (1747-L541/L542/L543).
• Ethernet/IP ping and EDS file handshake test for SLC 5/05 processors (1747-L551/L552/L553).
• Power supply output voltage and ripple measurement under rated load for all 1746-P series units.
• Relay contact resistance measurement and cycle test for 1746-OW16 output modules.
• Analog calibration verification (±0.1% full scale) for all 1746-NI4 and 1746-NO4I modules.

All tested units are tagged with inspection date, technician ID, and test result record prior to shipment.