Allen-Bradley 1745-LP102 Replacement/Upgrade for SLC 100

Product Overview

Allen-Bradley 1745-LP102 Replacement/Upgrade for SLC 100: Smooth Migration from Legacy Control Systems

The Allen-Bradley 1745-LP102 is a processor unit from the SLC 100 series — one of Rockwell Automation’s earliest programmable controller platforms widely deployed in discrete manufacturing, material handling, and process control applications throughout the 1980s and 1990s. As the SLC 100 platform has reached end-of-life and spare parts become increasingly scarce, facilities running 1745-LP102-based control panels face mounting pressure to source verified replacement units or execute a structured migration to a supported architecture.

TOPNLMS supplies tested, ready-to-ship 1745-LP102 processor units for direct drop-in replacement, as well as engineering guidance for customers planning a controlled upgrade path to modern Allen-Bradley platforms. Whether your priority is minimizing unplanned downtime with an immediate like-for-like swap, or executing a planned retrofit during a scheduled maintenance window, this page covers the compatibility considerations, upgrade options, and procurement assurances you need to make a confident decision.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful migration away from the 1745-LP102 rarely involves the processor alone. In practice, the upgrade touches multiple layers of the control architecture. For customers executing a like-for-like swap, the 1745-LP102 processor slots directly into the existing SLC 100 chassis alongside the original 1745-series I/O modules, preserving existing field wiring and terminal block assignments. This approach is ideal when the control program is already archived and the goal is simply to restore a failed or failing processor with zero rewiring.

For facilities planning a more comprehensive modernization, the migration typically begins with the processor and expands outward. Replacing the 1745-LP102 with a 1747-L532 SLC 5/03 processor, for example, requires transitioning to a 1746-series modular I/O rack. In this scenario, 1746-IB16 digital input modules and 1746-OB16 digital output modules are commonly used to replicate the I/O point count of the original fixed system. Analog signals previously handled by legacy 1745-series analog I/O are remapped to 1746-NI4 or 1746-NO4I analog modules, maintaining signal integrity without replacing field instrumentation.

Communication infrastructure is another critical consideration. The 1745-LP102 communicates over DH-485, and many existing HMI panels — including older PanelView 300 or PanelView 550 terminals — are wired to this network. During migration, a 1747-AIC Advanced Interface Converter or a 1761-NET-AIC network interface module is often used to bridge the legacy DH-485 segment to the new processor, allowing the existing HMI to remain operational while the control program is converted and validated. For customers ready to upgrade the HMI simultaneously, a PanelView Plus 7 Standard terminal with EtherNet/IP connectivity provides a modern operator interface that integrates cleanly with SLC 5/05 or MicroLogix 1100 processors.

Power supply compatibility must also be verified. The SLC 100 platform uses an integrated power supply within the processor unit, while an SLC 500 migration requires a dedicated 1746-P4 or 1746-P7 power supply module sized to the I/O load. In retrofit projects where panel space is constrained, a 1606-XLP power supply from the Bulletin 1606 series is sometimes used as an auxiliary 24 VDC source for field devices, freeing the main rack power supply for processor and I/O card loads exclusively.

For sites where the DH-485 network spans multiple control panels or remote I/O drops, a 1747-SDN DeviceNet Scanner or a 1756-ENBT EtherNet/IP bridge module may be introduced to consolidate remote I/O communication under a single, maintainable network backbone. This is particularly relevant in automotive assembly, food processing, and water treatment facilities where the original SLC 100 installation predates modern fieldbus standards.

Retrofit Guidance FAQ

Q: Can I reuse my existing field wiring when replacing the 1745-LP102?
A: For a direct 1745-LP102 to 1745-LP102 swap, yes — all existing terminal block connections, I/O wiring, and field device cabling remain unchanged. For a migration to SLC 500 or MicroLogix, field wiring must be re-terminated to the new I/O module terminal blocks, though the field cable runs themselves are typically reusable.

Q: Is my existing APS ladder program compatible with RSLogix 500?
A: APS programs (.PLC files) can be imported into RSLogix 500 with the APS-to-RSLogix conversion utility. Most standard ladder instructions translate directly; however, program-controlled I/O addressing must be reviewed and updated to reflect the new 1746-series I/O slot assignments.

Q: Will my DH-485 HMI still communicate with a replacement 1745-LP102?
A: Yes. A replacement 1745-LP102 maintains full DH-485 compatibility. Node addressing and baud rate settings are preserved from the original unit configuration, so HMI communication is restored immediately upon processor replacement without any network reconfiguration.

Q: How much additional panel space is required for an SLC 500 migration?
A: A 4-slot 1746-A4 rack with power supply occupies approximately 200mm × 180mm of panel space. A 10-slot 1746-A10 rack requires approximately 400mm × 180mm. In tight enclosures, a MicroLogix 1100 (1763-L16BWA) offers a compact alternative with integrated I/O and EtherNet/IP, fitting within a much smaller footprint.

Q: What is the typical commissioning time for a 1745-LP102 drop-in replacement?
A: With a pre-loaded program and verified hardware, a like-for-like processor swap typically takes 30–90 minutes including power-down, module exchange, program download, and I/O verification. Planned retrofit migrations involving I/O rewiring and program conversion are typically scoped as 1–3 day shutdown projects.

Warranty Assurance

Every 1745-LP102 unit shipped by TOPNLMS is covered by a 12-month warranty from the date of delivery. Prior to dispatch, each unit undergoes functional verification including power-on self-test, I/O communication check, and visual inspection for connector integrity and board condition. Units are packed in anti-static ESD-safe packaging with foam cushioning to prevent transit damage.

In the event of a warranty claim, TOPNLMS provides a replacement unit or full refund within the warranty period. Our technical support team is available to assist with installation questions, program compatibility queries, and commissioning guidance. Typical order processing time is 1–3 business days, with express shipping options available for emergency breakdown situations. We ship from Xiamen, China, with DHL, FedEx, and UPS express services covering most global destinations within 3–7 business days.

For volume procurement, OEM integration projects, or standing blanket orders for MRO inventory programs, please contact our sales team directly to discuss pricing, lead times, and quality documentation requirements including test reports and certificates of conformance.