Configured for controller execution and EtherNet/IP data exchange in the On-Machine ControlLogix platform, the Allen-Bradley 1756-L72EROM (1756-L72EROM Armor ControlLogix Controller) provides 4 MB of standard memory, embedded EtherNet/IP interfaces, and 24 VDC machine power connection. Rockwell Automation identifies it as an Armor ControlLogix 5570 controller with IP67 enclosure protection.

Model Identification

The 1756-L72EROM is a standard Armor ControlLogix controller rather than the safety-rated 1756-L72EROMS. The L72EROM provides 4 MB of standard memory and 0.98 MB of I/O memory, while the L72EROMS adds 2 MB of safety memory.

The Armor ControlLogix family is designed for On-Machine installation and integrates controller processing with embedded EtherNet/IP communication and pass-through DC power connections.

Hardware Specifications

Rockwell Automation specifies 4 MB standard memory, 0.98 MB I/O memory, 128,000 maximum total and digital I/O, 4,000 maximum analog I/O, and 18-32 VDC input operation. The manufacturer also specifies 18-32 VDC at 8 A for system input power and 18-32 VDC at 6 A for external output power.

The current product data identifies the 1756-L72EROM as an ArmorControlLogix On Machine Controller. The product cut sheet specifies dual EtherNet/IP ports, USB, a 4-character alpha/numeric display, and IP67 protection.

EtherNet/IP and I/O Architecture

The controller incorporates embedded EtherNet/IP communication rather than requiring a separate chassis communication module. Rockwell Automation describes the Armor ControlLogix architecture as equivalent to two embedded 1756-EN3TR modules, providing dual independent Ethernet ports and support for Device Level Ring topology.

The embedded network interface supports EtherNet/IP control and data traffic directly from the On-Machine controller. The controller does not support controller redundancy, so redundant ControlLogix processor configurations are not applicable to the 1756-L72EROM.

On-Machine Power and Physical Integration

The controller accepts a nominal 24 VDC supply over an 18-32 VDC input range. System input power is specified at 18-32 VDC at 8 A. Separate output and pass-through power paths are provided for other On-Machine devices.

The Armor enclosure is intended for machine-level installation rather than a conventional ControlLogix chassis slot. The product cut sheet specifies an IP67 enclosure, while the product profile describes captive screws, a rotating hinge, flexible mounting brackets, and embedded 24 VDC power distribution.

Firmware and Control Platform

The 1756-L72EROM uses the ControlLogix 5570 controller architecture and is programmed within the Logix controller engineering environment. Rockwell Automation lists Relay Ladder, Structured Text, Function Block, and Sequential Function Chart as programming languages for the Armor ControlLogix platform.

Firmware and project compatibility should be checked against the installed controller revision and the Logix Designer software version before downloading a project. Controller memory consumption can change with firmware and software revisions.

Ordering Information

• 1 x Allen-Bradley 1756-L72EROM Armor ControlLogix 5570 Controller
• 1 x Integrated controller housing with embedded EtherNet/IP interfaces
• 1 x 1 GB Secure Digital memory card, supplied with the controller according to Rockwell Automation documentation
• Mounting hardware and field wiring accessories should be selected according to the machine installation design.
• No separate ControlLogix chassis is required for the controller itself because the Armor platform is an On-Machine controller.

Installation and Wiring Guidelines

Power connection

• Apply a regulated 24 VDC supply within the specified 18-32 VDC input range.
• Size the supply wiring for the specified system input current.
• Verify polarity before energizing the controller.
• Calculate downstream loads when using the controller's external and pass-through power connections.

EtherNet/IP connection

• Use suitable industrial-rated M12 Ethernet cabling.
• Maintain physical separation between Ethernet wiring and high-energy switching conductors.
• Check connector engagement and cable routing before commissioning.
• Use the two independent Ethernet interfaces according to the intended network topology.

Mechanical installation

• Mount the controller using the specified Armor mounting provisions.
• Maintain access to the controller status display, USB interface, SD card access, power controls, and connectors.
• Do not obstruct the enclosure surfaces required for heat transfer.

Grounding and shielding

• Bond the machine enclosure and associated metallic structures according to the plant grounding design.
• Terminate cable shields according to the selected Ethernet cabling and machine grounding scheme.
• Avoid unintended shield-current paths through separate equipment grounds.

Frequently Asked Questions

• What is the standard memory capacity of the 1756-L72EROM?
  The controller provides 4 MB of standard memory and 0.98 MB of I/O memory. It does not provide the safety memory included in the L72EROMS variant.
• What supply voltage does the controller require?
  The nominal input voltage is 24 VDC, with an allowed input range of 18-32 VDC. System input power is specified at 8 A.
• Does the controller use EtherNet/IP directly?
  Yes. The Armor ControlLogix architecture provides embedded EtherNet/IP interfaces equivalent to two integrated 1756-EN3TR modules.
• Is controller redundancy supported?
  No. Rockwell Automation specifies controller redundancy as not supported for Armor ControlLogix controllers.
• What is the maximum I/O capacity?
  The specified maximum is 128,000 total I/O points, including up to 128,000 digital I/O and 4,000 analog I/O.
• Does the 1756-L72EROM include nonvolatile memory?
  Yes. Rockwell Automation specifies a 1 GB Secure Digital card supplied with the controller for nonvolatile storage.
• What enclosure protection does the controller provide?
  The product cut sheet identifies the 1756-L72EROM as an IP67 Armor ControlLogix On-Machine controller.
• Is the 1756-L72EROM a safety controller?
  No. It is the standard Armor ControlLogix controller. The 1756-L72EROMS is the corresponding safety controller with additional safety memory.