Allen-Bradley 1764-LSP MicroLogix 1500 Standard Processor Module

Description

Product Introduction

The Allen-Bradley 1764-LSP is the standard logic processor module for the MicroLogix 1500 controller platform. Designed to snap directly into any 1764 base unit (such as the 1764-24BWA or 1764-24AWA), it houses the CPU, execution engine, user program memory, and primary RS-232-C serial communication port.

Unlike the dual-port 1764-LRP, the LSP features a streamlined single Channel 0 RS-232 port supporting DF1, DH-485, and Modbus RTU protocols. Its standalone, slide-in form factor allows plant technicians to replace logic hardware or swap controllers without disturbing field I/O terminal wiring on the base unit below.

Key Technical Specifications

Application Scenarios & The “Trench” Experience

The Trench Story

It is 3:30 AM during a heavy rainstorm. A lightning surge passes through an ungrounded RS-232 serial telemetry cable, frying the comm transceiver chip inside a 1764-LSP processor running a municipal water pump station. The pump status is offline, and a holding tank is twenty minutes away from overflowing. Because the base unit and field wiring are completely untouched, you pull the dead 1764-LSP processor out of its base, snap in a pre-programmed replacement LSP module, turn the keyswitch to RUN, and restore full pump station control in under five minutes.

Specific Applications

• Pumping & Lift Stations: Runs cyclic pump alternation logic and transmits system alarms over serial radios using Modbus RTU slave protocol.
• Industrial Oven Control: Executes temperature ramp/soak profiles while managing safety interlocks and blower contactors via base relay outputs.
• Automated Pallet Wrappers: Handles fast proximity sensor feedback and controls drive contactors with tight 1ms/1k scan times.
• Basic OEM Skid Controls: Serves as a compact logic engine for chemical dosing, air compressor control, or lube oil skids.

1764-LSP

1764-LSP

1764-LSP

Transparency SOP: Quality Assurance & Testing

We test every 1764-LSP processor on live test benches before putting it in anti-static storage:

1. Physical Inspection: We verify gold backplane edge contacts for scratch wear, check plastic locking clips, and inspect the 8-pin Mini-DIN port for bent pins.
2. Backplane Docking Handshake: The module is inserted into a 1764-24BWA base unit to verify power-up self-tests and CPU-to-base communication paths.
3. Firmware & Memory Audit: We check internal flash integrity, clear fault logs, and verify full write capability across all 7.65 KB of user memory registers.
4. Channel 0 Serial Stress Test: We execute continuous packet transfers over RS-232 DF1 at 19.2k baud to ensure the serial communication transceiver operates under heavy load.
5. Battery Circuit Voltage Verification: We meter the internal lithium battery hold-up circuit under load to guarantee memory retention during power outages.

The Veteran’s Tech Trap Guide

• ⚠️ Do Not Snap or Pull Under Power: Always shut off line power to the 1764 base unit before removing or installing the 1764-LSP processor. Sliding the edge connector in live will arc the backplane power pins and permanently destroy the CPU board.
• ❗ Beware of the BAT LO Light: If the red “BAT LO” LED turns on, your ladder logic and data registers are living on borrowed time. Replace the lithium battery (1747-BA) immediately while power is applied to avoid losing the program on the next power down.
• ⚠️ Lost Comm Connection Reset: If you can’t go online because someone changed the Channel 0 port settings, open the front door and press the DCOMM toggle button. The DCOMM LED will light up, forcing the serial port to factory defaults: DF1 Full-Duplex, 19200 Baud, Parity None, Node 1.
• ❗ LSP vs. LRP Comm Port Limits: Remember that the 1764-LSP only has ONE serial port (Channel 0). If your system requires an HMI on one port and a SCADA radio network on another simultaneously, you need the 1764-LRP processor instead.

Frequently Asked Questions

Q: Can I upgrade a system running a 1764-LSP to a 1764-LRP?

Yes. The 1764-LRP processor fits into the exact same 1764 base unit. The LRP gives you double the memory (14 KB), an extra RS-232 port (Channel 1), and a built-in real-time clock. Your RSLogix 500 program can be converted to an LRP target in seconds.

Q: How do I back up my program without a computer?

You can install an optional memory module (such as the 1764-MM1 or 1764-MM2 EEPROM card) into the slot on the front of the 1764-LSP. This allows you to store a non-volatile backup of your ladder program and set the controller to auto-load on power-up.

Q: Will a 1764-LSP processor work in a MicroLogix 1200 or 1100?

No. The 1764-LSP is built specifically for the MicroLogix 1500 modular platform. MicroLogix 1100 and 1200 PLCs use integrated brick architectures where the processor cannot be unclipped from the power supply.

Q: What happens if the internal battery dies completely?

If the battery dies and line power is cycled, all user programs and non-retentive data in the RAM memory will be erased, causing a solid red FAULT light. You must load a backup memory card or re-download the project via RSLogix 500.

Q: What warranty comes with these discontinued processors?

We cover all new surplus and refurbished 1764-LSP processors with a full 12-month replacement warranty. If the hardware fails under normal operating conditions within 365 days, we exchange it or refund your order.

Q: Is RSLogix Micro compatible with the 1764-LSP?

Yes. Both RSLogix 500 (Standard/Professional) and RSLogix Micro (Starter/Developer) fully support programming, monitoring, and flashing the 1764-LSP processor.