Configured for standard and safety control execution over EtherNet/IP in an On-Machine architecture, the Allen-Bradley 1756-L72EROMS (1756-L72EROMS Armor GuardLogix Controller) provides 4 MB standard memory, 2 MB safety memory, dual independent EtherNet/IP interfaces, and a 24 VDC power interface. Rockwell Automation identifies the catalog number as an Armor GuardLogix 5570 controller.

Model and Variant Identification

The 1756-L72EROMS is the safety version of the Armor ControlLogix 5570 controller family. The manufacturer specifies 4 MB of standard memory and 2 MB of safety memory. Unlike the standard 1756-L72EROM, the safety model does not list the 0.98 MB I/O memory allocation or the 128,000-point I/O limits in the current technical data.

The suffix OMS identifies the Armor GuardLogix safety controller variant. Rockwell Automation distinguishes the 1756-L72EROMS from the standard 1756-L72EROM by its safety control capability and safety memory allocation.

Hardware Specifications

Rockwell Automation specifies approximately 7.15 kg for the 1756-L72EROMS and dimensions of 240.0 x 292.0 x 164.52 mm. The supplied 0.26 kg weight and 3.5 x 114.3 x 14.5 cm shipping dimensions do not correspond to the manufacturer's published hardware data and should not be treated as product dimensions.

Functional Safety and Network Architecture

The 1756-L72EROMS is classified by Rockwell Automation as an Armor GuardLogix controller. The Armor GuardLogix family supports safety applications up to SIL 3 and Performance Level PLe, Category 4, when configured and used according to the applicable safety documentation.

The controller provides dual independent EtherNet/IP ports and Device Level Ring capability. The network architecture is intended to maintain communication through a single network connection failure when configured as a DLR network.

The safety controller supports Relay Ladder Logic, Structured Text, Function Block Diagram, and Sequential Function Chart for standard controller programming. The safety task supports Relay Ladder Logic and the specified additional safety instructions.

Controller redundancy is not supported for the Armor ControlLogix and Armor GuardLogix 5570 controllers.

Safety Memory and Firmware Compatibility

The 1756-L72EROMS contains 2 MB of dedicated safety memory in addition to its 4 MB standard memory allocation. The safety memory differentiates this controller from the standard 1756-L72EROM.

Rockwell Automation states that the functional safety certification is applicable when the controller is used with specified firmware revisions and according to the relevant GuardLogix safety reference documentation. The safety rating should therefore be evaluated together with controller firmware, application configuration, and the associated safety I/O architecture.

The USB interface is intended for temporary local programming and is not intended for permanent connection.

Ordering Information

• 1 x Allen-Bradley 1756-L72EROMS Armor GuardLogix 5570 Controller
• 1 x Integrated controller enclosure and electronics assembly
• 1 x Embedded USB programming interface
• 1 x Integrated Ethernet communication interface
• 1 x Secure Digital memory card interface
• Memory cards are selected according to the supported Armor GuardLogix accessories and are not automatically assumed unless specified by the individual order configuration.
• External 24 VDC power wiring, Ethernet cables, mounting hardware, and safety I/O devices are separate system components.

Installation and Wiring Guidelines

Power connection

• Use a 24 VDC source within the specified 18-32 VDC input range.
• Size the incoming power circuit for the published 8 A system power interface.
• Verify polarity and connector pin assignments before energizing the controller.
• Observe the separate pass-through and external output power ratings when supplying additional On-Machine equipment.

EtherNet/IP connection

• Use compatible M12 Ethernet connections and suitable industrial twisted-pair cable.
• The manufacturer specifies Category 5e Ethernet cabling and shielded or unshielded twisted-pair construction.
• Keep Ethernet wiring separated from high-energy switching conductors.
• For DLR operation, verify the intended ring topology before commissioning.

Grounding

• Connect the protective earth conductor according to the specified grounding arrangement.
• The manufacturer specifies PE ground conductor sizes from 1.3 to 5.2 mm2 and a terminal torque of 2 N m.
• Avoid unintended shield-current paths through multiple grounding points.

Environmental installation

• Maintain an ambient operating temperature from 0 to 60 deg C.
• Maintain relative humidity within 5 to 95% noncondensing.
• The enclosure is rated UL Type 4/4x.
• The product meets IP67 when marked and the receptacle dust caps or cable terminations are correctly installed.

Frequently Asked Questions

• What is the standard memory of the 1756-L72EROMS?
  The controller provides 4 MB of standard memory. It is paired with a separate 2 MB safety memory allocation for GuardLogix safety applications.
• How much safety memory is provided?
  The 1756-L72EROMS provides 2 MB of safety memory. This is the primary memory distinction from the standard 1756-L72EROM controller.
• Does the controller support SIL 3?
  Yes. Armor GuardLogix 5570 controllers are capable of SIL 3 and PLe Category 4 when used with specified firmware and the required safety system architecture.
• What Ethernet interfaces are integrated?
  The controller provides 4 M12 Category 5e Ethernet ports. Its architecture supports dual independent EtherNet/IP connections and DLR capability.
• What is the USB interface specification?
  The local programming interface is USB 1.1 Full Speed at 12 Mbps. Rockwell Automation specifies that the USB port is intended for temporary programming use.
• What supply voltage is required?
  The nominal input voltage is 24 VDC, with an allowed range of 18-32 VDC. The published system power interface is rated at 8 A.
• Is controller redundancy supported?
  No. Rockwell Automation specifies that controller redundancy is not supported for the Armor ControlLogix and Armor GuardLogix 5570 family.
• What is the environmental temperature range?
  The specified operating range is 0 to 60 deg C. Nonoperating storage is specified from -40 to +85 deg C, with 5 to 95% noncondensing humidity.