OMRON CK3M-CPU120 Motion Controller Module – CK3M Series

OMRON CK3M-CPU120 Multi-Axis Motion Controller: Deterministic Axis Coordination in Compact Industrial Form

The CK3M-CPU120 is the entry-level CPU module within OMRON’s CK3M Programmable Multi-Axis Controller (PMAC) platform, designed to govern up to two servo axes over a real-time EtherCAT motion bus. Unlike conventional PLC-embedded motion blocks, the CK3M architecture separates motion trajectory computation from standard ladder logic execution, assigning each domain its own deterministic scan cycle. This structural separation eliminates jitter accumulation across axis interpolation boundaries — a critical requirement in applications where positional repeatability must remain within ±1 µm across extended production runs.

The module mounts on a DIN rail and interfaces with the CK3W backplane expansion system, allowing engineers to scale axis count incrementally without redesigning the control cabinet. The CPU communicates with downstream EtherCAT slave drives — including OMRON’s 1S and G5 servo series — at a default cycle time of 500 µs, with optional reduction to 250 µs for high-dynamic applications. All trajectory data, including electronic cam tables and gear ratio parameters, resides in non-volatile flash memory, ensuring motion profiles survive power interruptions without re-initialization overhead.

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Technical Parameters

Hardware Logical Analysis

EtherCAT Distributed Clock Synchronization: The CK3M-CPU120 acts as the EtherCAT master, distributing a hardware-synchronized clock signal to all slave nodes on the network segment. Each slave’s internal timer is phase-locked to the master reference with a synchronization accuracy of <1 µs. This mechanism ensures that torque commands issued to multiple servo drives arrive within the same 250 µs window, eliminating the inter-axis timing skew that causes contouring errors in multi-axis interpolation paths.

Dual-Core Processing Architecture: The CPU module separates motion trajectory computation from I/O scan and communication handling at the silicon level. The motion core executes position, velocity, and torque loop calculations on a fixed-priority real-time kernel, while the application core handles Sysmac Studio communication, variable mapping, and HMI data exchange. This isolation prevents application-layer latency spikes from propagating into the motion execution thread — a common failure mode in single-core PMAC designs under heavy network load.

EMC Design and Isolation: The module’s internal power supply incorporates a DC-DC converter with common-mode choke filtering on both input and output rails, attenuating conducted emissions in the 150 kHz–30 MHz band to comply with EN 55011 Class A limits. The EtherCAT physical layer uses transformer-coupled 100BASE-TX, providing 1,500 V galvanic isolation between the motion bus and the CPU’s internal logic ground. This isolation architecture prevents ground loop currents — generated by servo drive PWM switching — from coupling into the CPU’s reference voltage, which would otherwise manifest as position feedback noise.

Non-Volatile Motion Profile Storage: Electronic cam tables, gear ratio parameters, and homing sequences are stored in internal flash memory with a write endurance of ≥100,000 cycles. On power restoration, the CPU reloads all motion parameters within 800 ms, enabling rapid restart without requiring a full Sysmac Studio download cycle. This is particularly relevant in applications with frequent planned shutdowns, such as shift-change maintenance windows in food processing or pharmaceutical packaging lines.

Backplane Expansion Bus: The CK3W expansion interface uses a proprietary high-speed parallel bus operating at 100 Mbps, connecting the CPU to I/O expansion modules (CK3W-AX series) with a fixed inter-module latency of <10 µs. The bus arbitration logic uses a token-passing protocol that guarantees each expansion module a deterministic service window within every CPU scan cycle, preventing starvation of lower-priority I/O modules during peak motion computation loads.

System Integration Benefits

• Unified PLC + Motion Programming: Sysmac Studio provides a single IDE for IEC 61131-3 ladder/structured text logic and motion function blocks (PLCopen MC standard), eliminating the need for separate motion programming tools and reducing commissioning time by consolidating variable namespaces.
• Deterministic Real-Time Response: The 250 µs EtherCAT cycle time with distributed clock synchronization delivers axis-to-axis jitter below 1 µs, meeting the timing requirements of electronic gearing and cam applications in high-speed packaging machinery.
• Scalable Axis Architecture: Starting at 2 axes with the CK3M-CPU120, engineers can expand to higher axis counts by adding CK3W-AX1414 or CK3W-AX0808 expansion modules without replacing the CPU, protecting capital investment as machine complexity grows.
• Diagnostic Transparency: The module exposes axis status, following error, torque utilization, and communication health as standard Sysmac variables, accessible in real time via HMI or SCADA without custom polling routines.
• Electronic Cam and Gearing: Native support for electronic cam tables (up to 1,024 points per axis) and electronic gearing with configurable gear ratios enables complex synchronized motion profiles — such as flying shear or rotary knife — to be implemented entirely in software without mechanical cam mechanisms.
• Rapid Homing Sequences: Configurable homing methods (including torque-limit homing and encoder Z-pulse homing) are executed autonomously by the motion core, freeing the application CPU from managing low-level homing state machines and reducing homing cycle time.
• Sysmac Studio Trace Function: Built-in data trace capability records axis position, velocity, and torque at the motion cycle rate (250 µs resolution), providing engineers with oscilloscope-grade waveform data for tuning servo gains without external measurement equipment.
• Interoperability with Third-Party EtherCAT Slaves: The CK3M-CPU120 supports CoE (CANopen over EtherCAT) and SoE (Sercos over EtherCAT) device profiles, enabling integration with non-OMRON servo drives and I/O terminals that conform to the ETG.1000 EtherCAT specification.
• Compact Panel Footprint: At 55 mm width on DIN rail, the module occupies significantly less panel space than rack-based PMAC systems, reducing enclosure size and associated material costs in space-constrained machine designs.

Quality Assurance & Global Logistics

Every CK3M-CPU120 unit supplied by siemensplc.com is sourced through verified OMRON distribution channels. Units are inspected upon receipt for label integrity, serial number format consistency, and packaging condition. Where stock permits, power-on verification and EtherCAT communication handshake testing are performed prior to dispatch. Each shipment is accompanied by a packing list and, upon request, a supplier traceability record linking the unit’s serial number to its distribution chain.

Logistics operations are based in Xiamen, China, with access to major international freight carriers including DHL Express, FedEx International Priority, and UPS Worldwide Expedited. Standard in-stock orders are dispatched within 1–2 business days. Export documentation — including commercial invoice, packing list, and certificate of origin — is prepared for all international shipments. Bulk orders qualify for sea freight consolidation with competitive volumetric rates. The 12-month warranty covers manufacturing defects under normal operating conditions; DOA claims are processed within 5 business days of receipt confirmation.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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