Product Overview

The Allen-Bradley 1756-L55M12 is a ControlLogix 5555 controller. This processor module belongs to the ControlLogix series of programmable automation controllers. It provides 750 kbytes of user memory for data and logic.

The controller has 208 kbytes of I/O memory. However, it does not include nonvolatile memory. Therefore, a battery is required to retain programs during power loss.

General Specifications

The 1756-L55M12 offers robust processing capabilities for ControlLogix systems.

• Manufacturer: Rockwell Automation.

• Brand: Allen-Bradley.

• Series: ControlLogix.

• Part Number/Catalog No.: 1756-L55M12.

• Module Type: Processor Module (Logix5555).

• RAM: 750 Kilobytes (user memory).

• I/O Memory: 208 Kilobytes.

• Maximum I/O: 128,000.

• Maximum Analog I/O: 4,000 Input, 2,000 Output.

• Program Scan Time: 0.08 milliseconds.

• Weight: 0.35 kilograms (0.78 pounds).

• UPC: 10612598286628.

Power and Backplane Current

The 1756-L55M12 draws power from the ControlLogix backplane.

• Backplane Current (5 Volts DC): 1.23 Amps.

• Backplane Current (24 Volts DC): 14 milliamps (0.014 A).

• Power Dissipation: 5.6 Watts.

• Thermal Dissipation: 19.1 BTU/hr.

Memory and Battery

The 1756-L55M12 requires a battery for program retention.

• Battery Types: 1756-BA1 or 1756-BATM.

• Battery Weight: 0.59 grams (lithium).

• Nonvolatile Memory: Not included.

Therefore, a battery is essential to retain the user program when power is removed.

Communication Protocols

The 1756-L55M12 supports multiple communication networks.

• ControlNet.

• EtherNet/IP.

• DH+ (Data Highway Plus).

• DeviceNet.

• Universal remote I/O networks.

Consequently, it integrates with diverse automation devices and networks.

Redundancy Support

The 1756-L55M12 can be used in a redundant controller system. However, redundant configurations require a ControlNet network. For this reason, proper network planning is essential for high-availability applications.

Environmental Specifications

The 1756-L55M12 withstands typical industrial conditions.

Temperature Ranges:

• Operating Temperature: 0 to 60°C (32 to 140°F).

• Storage Temperature: -40 to 85°C (-40 to 185°F).

Humidity:

• Relative Humidity: 5% to 95% (non-condensing).

Vibration:

• Operating Vibration: 2g at 10 to 500 Hz.

• Tested Vibration: 10-500 Hertz.

Shock:

• Operating Shock: 30g.

• Non-operating Shock: 50g.

Electrical Immunity and Isolation

The 1756-L55M12 provides robust electrical protection.

• Conducted RF Immunity: 10V rms with 1 kHz sine-wave 80% AM from 150 kHz to 80 MHz.

• Isolation Voltage: 30V continuous, basic insulation type.

• Dielectric Withstand Tested: 707V DC for 60 seconds.

• Wiring Category: 2 (on communication ports).

Enclosure and Cabling

The 1756-L55M12 has specific physical characteristics.

• Enclosure Type: Open style.

• Serial Cables: Compatible with 1756-CP3 or 1747-CP3 serial cables.

Key Features

The 1756-L55M12 offers several advantages for control applications.

High I/O Capacity:
Supports up to 128,000 maximum I/O. Therefore, it suits large-scale automation systems.

Fast Scan Time:
Program scan time is 0.08 milliseconds. Consequently, it handles high-speed control requirements effectively.

Redundant Controller Support:
Can be used in redundant configurations on ControlNet networks. Hence, it provides high-availability solutions.

Multiple Network Support:
Communicates over ControlNet, EtherNet/IP, DH+, DeviceNet, and universal remote I/O. Thus, it integrates into existing multi-network environments.

Compact Form Factor:
Weighs only 0.35 kg. For this reason, it adds minimal load to the backplane.

Battery-Backed Memory:
Uses 1756-BA1 or 1756-BATM batteries for program retention. Therefore, programs are preserved during power outages.

Wide Operating Temperature:
Operates from 0 to 60°C. Hence, it suits industrial control rooms and enclosures.

Typical Applications

The 1756-L55M12 suits various control applications.

• Large-scale manufacturing process control.

• High-I/O count automation systems.

• Redundant controller applications (on ControlNet).

• Multi-network integration projects.

• Retrofit upgrades to existing ControlLogix systems.

Installation Guidelines

Install the 1756-L55M12 in any slot of a ControlLogix chassis (typically slot 0). First, ensure the chassis power supply can provide the required 1.23 A at 5V and 14 mA at 24V. Then, insert the processor into the slot.

Install a 1756-BA1 or 1756-BATM battery for program retention. Connect programming devices via serial cable (1756-CP3 or 1747-CP3). For network communication, configure the desired protocol (ControlNet, EtherNet/IP, DH+, DeviceNet, or universal remote I/O).

For redundant controller systems, both processors must communicate over a ControlNet network. The operating temperature range is 0 to 60°C. The open-style enclosure requires installation within a protected panel.

What is in the Box

Please inspect all items upon delivery.

• Allen-Bradley 1756-L55M12 Logix5555 processor module.

• Installation instruction manual.

• Anti-static protective bag.

Note: Battery (1756-BA1 or 1756-BATM) is sold separately unless specified.

Frequently Asked Questions (FAQ)

1. How much user memory does the 1756-L55M12 have?

The 1756-L55M12 provides 750 kilobytes of user memory for data and logic. It also has 208 kilobytes of I/O memory.

2. What is the maximum I/O capacity of this processor?

The 1756-L55M12 supports a maximum of 128,000 I/O points. This includes 4,000 analog inputs and 2,000 analog outputs.

3. Does this processor support redundant operation?

Yes. The 1756-L55M12 can be used in a redundant controller system. However, redundant configurations require a ControlNet network.

4. What battery types are compatible with this module?

The 1756-L55M12 uses either the 1756-BA1 or 1756-BATM lithium battery. Therefore, always keep a spare battery available.

5. What is the program scan time of this controller?

The 1756-L55M12 has a program scan time of 0.08 milliseconds. Consequently, it suits high-speed control applications.