Allen-Bradley 1756-L55M24 ControlLogix Processor

Allen-Bradley 1756-L55M24 ControlLogix 5555 controller bundled with a 3.5 MB nonvolatile 1756-M24 memory board. NJT Automation sources the 1756-L55M24 on request; send the part number for a replacement or repair quote.

Quote required. Request a quote below for pricing and delivery.

Actual NJT inventory photos

Request Replacement Quote Request Repair Quote

Part Number	1756-L55M24
Price	On Request Availability and condition determine final quote.
Description	ControlLogix 5555 controller.
Shipping	UPS Ground included \| Next-Day Air and Worldwide Shipping available at checkout
Warranty	1-year full-function warranty provided by NJT Automation. Warranty details Included 1 year, full-function 2 years +15% of product price 3 years +25% of product price View full warranty policy
Returns	90-day free returns. View return policy
Exchange	Send us your defective 1756-L55M24 after your purchase for a 10% core credit. We also purchase old or damaged parts outright.

Availability

Sourced on request

We do not have a 1756-L55M24 on the shelf right now. We can source one through our supplier network; request a quote and we confirm availability, price and lead time before you commit.

Sourcing

Sourced through our Level 1 network of vetted US suppliers. Each unit is checked before it ships and carries the same NJT warranty and return policy as our own stock. Quotes within one hour during business hours; typical delivery 3–5 business days, next-day air available. Sourced parts are not available for local pickup.

Request Quote How Level 1 sourcing works

Repairs

1756-L55M24 Mail-In Repair Service

Part Number Decoder

ControlLogix 5555 controller

1756L55M24

1756: BulletinControlLogix: Rockwell Automation's chassis-based control platform (controllers, I/O, communication modules, power supplies and chassis).
L: Module typeLogix controller (CPU module).
55: GenerationControlLogix 5555 (Logix5555): first-generation ControlLogix controller; requires a 1756-M1x / M2x memory board to run (RSLogix 5000 up to v16).
M24: Memory board3.5 MB user memory on a factory-fitted 1756-M24 memory board: nonvolatile flash (project survives battery loss after a manual Store).

Decoded from the Rockwell Automation catalog-number structure. Series and firmware revision are printed on the product label, not encoded here.

Series & Revisions

All series use the 1756-BA1 battery; on the L55 the memory board (1756-M1x/M2x) is part of the catalog number.

Series notes: RSLogix 5000 keys on catalog number and firmware revision, not series; flash the replacement to the project's revision.

Intended Use

Designed for plant-wide discrete, process, and motion control applications. ControlLogix controllers run high I/O-count machines, batch and continuous process lines, and coordinated multi-axis motion from a single chassis, with redundancy and plant-network connectivity when the application calls for it. Typical homes are automotive and tire plants, food and beverage lines, water and wastewater, oil and gas skids, and large packaging systems.

Migration Path

Rockwell Automation has discontinued the 1756-L1, L55 and L6x controllers. Published successor for the ControlLogix 5550 / 5555 / 5560: 1756-L71 (ControlLogix 5570) or 1756-L81E (ControlLogix 5580).

The chassis, power supply, I/O and communication modules stay; only the controller slot changes.
Open the project in Studio 5000 (v20 or later for L7x, v28 or later for L8xE), change the controller type, verify and download. 1756-RM085 is not needed; this is a Logix-to-Logix move.
The L7x/L8x have no RS-232 port and no battery: serial-connected HMIs or modems move to Ethernet or USB, CompactFlash gives way to a 1784-SD1 card, and the 1756-BA1/BA2 battery is replaced by the 1756-ESMCAP energy-storage module.

A like-for-like replacement or a repair keeps the existing program, wiring and panel layout; a migration is a project. Both are listed on this page so the choice can be made on lead time and budget.

Physical Data

Weight and DimensionsWeight0.87 lb (0.39 kg)H × W × D5.7 × 1.4 × 5.7 in. (145 × 35 × 145 mm)

Weight	0.39 kg (0.87 lb) Typical unit weight
Dimensions (H × W × D)	145 × 35 × 145 mm (5.7 × 1.4 × 5.7 in.) Single-slot controller module
Shipping Weight	0.92 kg (2.03 lb) Estimated: unit weight plus box and packing material; bills as 3 lb
Shipping Box (L × W × H)	12 × 12 × 8 in. (305 × 305 × 203 mm) Smallest standard box fitting the product with 3 in. cushioning per side

Product weight and dimensions are typical manufacturer-published values and may differ by series or option. Shipping box and weight are estimates for freight planning; the packed unit may ship in a different box.

Can the 1756-L55M24 be repaired?

Yes. NJT Automation repairs the 1756-L55M24 by mail-in: diagnostic evaluation, component-level repair and a functional test, backed by a 1-year full-function warranty.

NJT managed repair. No evaluation fee; no repair, no charge. Prepaid UPS label both ways, $650 minimum, rush available. 1-year full-function warranty included, 2- and 3-year options.

Get a repair quoteor text photos and symptoms to (414) 331-5954

Compare quotes from independent repair technicians. Post your repair on RepairMode to receive competitive bids from experienced technicians. Each technician sets their own pricing and warranty.

Find a PLC repair specialiston RepairMode.com ↗

Common failures

Failure patterns we regularly see on ControlLogix 5555 controller hardware like the 1756-L55M24:

Program lost on power cycle: battery-backed 1756-M1x memory board with a depleted battery
Memory board (1756-M12 / M13 / M14 / M16) failure showing as a solid red OK LED
RS-232 serial port damage from hot-plugged programming cables
Backplane communication faults from worn chassis connectors
Nonrecoverable major faults after a chassis power-supply brownout

Related services:PLC Repair All Repair Services

Photos by NJT Automation; test videos from NJT or network repair technicians.

Still have questions?

Find answers to shipping, warranties, repairs, and more.

Frequently Asked Questions

What is the 1756-L55M24?

The Allen-Bradley 1756-L55M24 is a ControlLogix 5555 controller bundled with a 3.5 MB nonvolatile 1756-M24 memory board.

What condition is it in?

The 1756-L55M24 may be available on request in Unused surplus / Refurbished / Used condition. We can quote this part in unused surplus, refurbished, or used condition depending on availability and your preference. Specify your requirement in the RFQ.

When does this part ship?

The 1756-L55M24 is sourced on request. Request a quote and we'll confirm availability and lead time, typically a few business days.