The Allen-Bradley 1756-L64/B, also cataloged as the 1756-L64 ControlLogix Processor, executes user logic, manages I/O data, and exchanges controller data through the ControlLogix chassis backplane.

Model Reference

The 1756-L64 is a member of the ControlLogix 5560 controller family. Rockwell Automation specifies 16 MB of user memory and 478 KB of I/O memory for this controller. The manufacturer lists the product as discontinued, with June 1, 2017 given as the discontinuation date.

The supplied spare references are 1756L64 and 1756-L64/B. Series B documentation identifies the 1756-L64 as a 16 MB controller supported with RSLogix 5000 version 16.

Hardware Specifications

Rockwell Automation specifies 16 MB user memory, 478 KB I/O memory, 128,000 maximum total I/O, 4,000 maximum analog I/O, 1200 mA at 5.1 VDC, 14 mA at 24 VDC, 3.5 W power dissipation, and 11.9 BTU/hr thermal dissipation.

The manufacturer identifies the 1756-L64 origin as United States of America. Controller weight varies by series, with the technical data listing approximately 0.32 kg for Series A and 0.35 kg for Series B.

ControlLogix Backplane and I/O Architecture

The 1756-L64 operates as a chassis-based controller and occupies one ControlLogix chassis slot. Supported chassis listed by Rockwell Automation include the 1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17.

The controller separates user program and data storage from I/O memory. The 16 MB user-memory allocation stores application data and logic, while 478 KB is allocated for I/O-related memory.

The specified I/O capacity is up to 128,000 digital I/O points, 4,000 analog I/O points, and 128,000 total I/O points. Actual usable capacity depends on the chassis configuration, controller revision, module configuration, and application memory requirements.

Firmware and Platform Compatibility

The 1756-L64 Series B controller is associated with RSLogix 5000 version 16 and later controller firmware revisions documented for the platform. Rockwell Automation also provides firmware downloads and EDS files specifically for the 1756-L64.

Firmware revisions can affect application memory requirements. Rockwell Automation documents additional memory consumption introduced by later RSLogix 5000 revisions, so project memory usage should be checked before firmware migration.

For replacement planning, firmware revision, controller series, application memory consumption, and installed I/O configuration should be checked before substituting another ControlLogix controller.

Ordering Information

• 1 x Allen-Bradley 1756-L64 ControlLogix Logix5564 Processor
• 1 x Processor module assembly
• Controller battery requirements depend on the controller series and application configuration.
• Compatible chassis, power supply, communication modules, and I/O modules are separate system components.
• Optional nonvolatile memory for this controller family uses CompactFlash media; the memory card is not included as part of the processor itself.

Installation and Commissioning

Chassis mounting

• Install the processor in a compatible ControlLogix chassis.
• Confirm chassis power capacity before applying the backplane load.
• Seat the module fully against the backplane connector before closing the locking mechanism.
• Maintain cabinet ventilation around the open-style module enclosure.

Backplane loading

• Account for 1200 mA at 5.1 VDC and 14 mA at 24 VDC when calculating chassis power supply loading.
• Include the processor together with every installed communication and I/O module in the total backplane power calculation.
• Verify the selected ControlLogix power supply against the calculated chassis load.

Communication and firmware

• Verify the controller series and firmware revision before downloading an application.
• Check project memory requirements after firmware or RSLogix 5000 version changes.
• Back up the existing controller project and nonvolatile memory before a planned firmware migration.

Environmental installation

• The module is an open-style device and should be installed within an appropriate industrial enclosure.
• Route controller communication wiring separately from high-voltage switching conductors.
• Follow the ControlLogix system grounding and wiring requirements for the specific chassis installation.

Frequently Asked Questions

• What is the user memory of the 1756-L64?
  The 1756-L64 provides 16 MB of user memory for controller data and application logic.
• How much I/O memory is available?
  The controller provides 478 KB of I/O memory for I/O-related data and controller communications.
• What is the maximum I/O capacity?
  Rockwell Automation specifies up to 128,000 total I/O points, including up to 128,000 digital and 4,000 analog I/O points.
• How much backplane current does the controller draw?
  The specified current draw is 1200 mA at 5.1 VDC and 14 mA at 24 VDC.
• What chassis position is required?
  The processor is chassis-based and can be installed in any slot of a compatible ControlLogix chassis.
• What is the isolation voltage rating?
  The specified isolation voltage is 30 V continuous with basic insulation for the applicable controller interface.
• Can firmware revision affect the application?
  Yes. Rockwell Automation documents changes in memory requirements between firmware and RSLogix 5000 revisions, so project capacity must be checked before migration.
• Is the 1756-L64 still a current product?
  No. Rockwell Automation lists the 1756-L64 as discontinued effective June 1, 2017.