The Omron CJ2M-CPU31, also cataloged as the CJ2M-CPU31 CPU Unit, operates as a dedicated hardware component for centralized logic control and industrial ethernet communication execution within Omron CJ2M Series automation systems.

Technical Identifier Matrix

• Base Part Number: CJ2M-CPU31
• Series Architecture: CJ2M Series
• Product Classification: CPU Unit with built-in EtherNet/IP
• Compliance Standards: UC1, N, L, CE

Hardware Specifications

EtherNet/IP Determinism and Backplane Bus Velocity

The Omron CJ2M-CPU31 features an integrated EtherNet/IP communication stack that handles cyclic implicit message exchanges and explicit messaging independently from the primary execution core. Real-time deterministic control is maintained alongside an LD instruction execution speed of 0.04 us per instruction.

The backplane interface manages communication velocity for up to 40 mountable expansion units, preventing processing overhead bottlenecks during high-density I/O scans. An internal current draw of 0.70 A at 5 VDC is drawn directly from the system power supply module. Firmware flash architecture supports onboard peripheral expansion via the dedicated front option board slot for serial or pulse I/O extensions.

Package Contents & Ordering Information

• 1x Omron CJ2M-CPU31 CPU Unit
• 1x CJ1W-BAT01 Backup Lithium Battery
• 1x Protective USB Slot Cap
• 1x Hardware Instruction Sheet

Field Installation Guidelines

• Cabinet Mounting: Secure the processor onto a standard 35 mm DIN rail or panel surface inside an IP54-rated metal enclosure. Ensure a minimum vertical clearance of 30 mm above and below the housing for proper heat dissipation.
• Backplane Connection: Slide the unit horizontally against the adjacent power supply module. Engage the top and bottom slider catches until an audible click confirms positive locking of the backplane bus pins.
• Functional Grounding: Connect a dedicated ground wire (2.0 mm sq. minimum) from the system power supply module functional ground (FG) terminal to earth ground. Maintain total path resistance below 100 ohm.
• EtherNet/IP Cabling: Connect Category 5e or Category 6 STP ethernet cabling to the RJ45 port. Route communication cables in dedicated conduits separated from high-voltage AC motor wires.
• Braid Shielding: Connect the RJ45 shield ground to the enclosure grounding infrastructure using a 360-deg braid shield configuration to attenuate high-frequency industrial noise.

Frequently Asked Questions

• What is the execution speed of a standard basic LD instruction on the CJ2M-CPU31?

  The controller executes basic ladder logic (LD) instructions at a minimum speed of 0.04 us per instruction.

• What current load does the CJ2M-CPU31 draw from the internal 5 VDC backplane supply?

  The module draws 0.70 A (700 mA) at 5 VDC directly from the rack power supply via the internal backplane bus.

• How many maximum mountable units are supported by this CPU processor?

  The architecture supports connections for up to 40 mountable expansion units across the system expansion racks.

• What communication interfaces are integrated natively onto the front panel of the CPU?

  The CPU features a built-in EtherNet/IP port, a USB programming connector, and one slot for optional communication daughter boards.

• What is the user program memory capacity of the CJ2M-CPU31?

  The user memory allocation accommodates a total program capacity of up to 5K steps.

• Can the CJ2M-CPU31 CPU unit be installed or removed while the backplane is energized?

  No, main input power to the rack power supply module must be disconnected prior to inserting or removing the CPU unit.

• What international safety and industrial standards does the module meet?

  The hardware complies with UC1, N, L, and CE certification marks for industrial control equipment.

• What is the maximum functional ground loop resistance allowed during installation?

  The single-point functional grounding system must maintain a ground loop resistance of less than 100 ohm.