Beckhoff CX2020-0121 Retrofit-Compatible CPU for Legacy Systems

Beckhoff CX2020-0121 Retrofit-Compatible CPU for Legacy Systems

The Beckhoff CX2020-0121 is a high-performance embedded PC CPU module engineered for demanding industrial environments and purpose-built for seamless integration into legacy Beckhoff CX-series control architectures. As automation engineers face increasing pressure to extend the operational life of aging control systems — or migrate away from discontinued platforms — the CX2020-0121 delivers a proven, drop-in-compatible upgrade path that minimises engineering risk, reduces downtime, and preserves existing program logic.

Designed as a direct retrofit replacement within the Beckhoff CX20xx series, this CPU module supports the same DIN-rail mounting footprint and backplane interface as predecessor units such as the CX2020-0090 and CX2020-0100, enabling engineers to swap the processing core without redesigning the control cabinet or rewiring terminal blocks. The module runs TwinCAT 3 runtime natively, ensuring full compatibility with existing PLC programs, motion sequences, and HMI screen layouts developed under TwinCAT 2 or TwinCAT 3 environments.

For plants operating legacy Beckhoff CX9000, CX1000, or CX5000 series controllers that have reached end-of-life, the CX2020-0121 represents a validated upgrade target. Its Intel® Atom™ multi-core processor and expanded RAM capacity allow engineers to consolidate control tasks previously distributed across multiple older CPUs, reducing hardware count and simplifying cabinet layouts.

Upgrade Compatibility Table

Retrofit Planning for Existing Automation Systems

A successful retrofit begins well before the first terminal block is loosened. When planning a CX2020-0121 installation to replace a discontinued or failing CPU, engineers should audit the full control node: the existing CX2100-0004 power supply module must be confirmed capable of sustaining the new CPU’s peak current draw, particularly when the backplane also hosts communication modules such as the CX2500-0060 PROFIBUS slave module or the CX2500-0030 CANopen master module.

On the I/O side, plants running legacy KL-series bus terminals (KL1408 digital input, KL2408 digital output, KL3202 PT100 analog input) can retain their existing wiring by bridging through an EK1100 EtherCAT coupler, which presents the K-bus terminal chain to the CX2020-0121’s EtherCAT master port. This approach eliminates the need to rewire field devices and preserves terminal block labelling — a critical advantage in facilities where as-built documentation is incomplete.

For sites migrating from PROFIBUS-based architectures, the EL6731 PROFIBUS DP master terminal inserted into the EtherCAT terminal chain allows the CX2020-0121 to continue polling legacy PROFIBUS slaves — including third-party drives, valve islands, and remote I/O stations — without replacing field wiring. Similarly, where Modbus RTU devices remain in service, the EL6021 serial communication terminal provides RS-232/RS-485 connectivity directly from the EtherCAT bus.

Module addressing must be re-mapped in TwinCAT 3 after installation. Engineers should export the existing variable mapping from the legacy TwinCAT 2 project and use the TC2-to-TC3 conversion utility to generate an initial TC3 project file. Manual review of function block (FB) library references is essential — particularly for motion control FBs that reference the legacy NC/PTP axis configuration — before the first online test.

Where the control cabinet also houses a CP6201 or CP6606 Panel PC acting as the operator interface, the HMI ADS route must be updated to reflect the new CPU’s IP address and AMS Net ID. Existing HMI screen layouts, alarm lists, and trend displays typically require no modification, provided the TwinCAT variable names are preserved during program migration.

Signal isolation should be reviewed for any analog I/O channels connected to field transmitters. If the legacy system used external signal isolators or KL3314 thermocouple input terminals, confirm that the EtherCAT-equivalent EL3314 thermocouple terminal is substituted correctly and that the channel scaling parameters are re-entered in the new TC3 project.

Downtime Control During System Migration

Minimising production downtime during a CPU swap requires a structured pre-commissioning approach. Before the scheduled maintenance window, engineers should complete a full backup of the existing TwinCAT project, including all PLC tasks, NC axis parameters, and I/O configuration files. A parallel test bench — using a spare CX2020-0121 unit loaded with the converted TC3 project — allows functional verification of all control sequences, interlock logic, and communication links before the live system is touched.

During the physical swap, the recommended sequence is: power down the control cabinet via the main isolator, document all terminal block wiring positions with photographs, remove the legacy CPU module from the backplane, seat the CX2020-0121, reconnect the CX2100-0004 power supply, and restore 24 V DC. The TwinCAT 3 runtime should be started in configuration mode first, allowing the engineer to verify that all EtherCAT slaves — including I/O couplers, communication modules, and any connected EL6731 PROFIBUS master terminals — are detected correctly before switching to run mode.

Program logic continuity is protected by ensuring that all retain variables and persistent data blocks are backed up from the legacy CPU’s non-volatile memory prior to removal. On the CX2020-0121, these values are restored via the TwinCAT Boot Project mechanism, preserving production counters, recipe parameters, and setpoint tables without manual re-entry.

For critical processes where even a brief interruption is unacceptable, a hot-standby migration strategy — using a temporary parallel control path via a secondary EK1100 coupler branch — can maintain field device control during the CPU transition. All units supplied by NINERMAS are shipped after full functional testing, and the 12-month warranty covers the replacement period from the date of delivery.

Retrofit Support FAQ

Q1: Is the CX2020-0121 a direct drop-in replacement for the CX2020-0090 or CX2020-0100?
The CX2020-0121 shares the same CX20xx backplane form factor and 24 V DC power interface as the CX2020-0090 and CX2020-0100. The primary difference is the processor generation and RAM capacity. Existing EtherCAT terminal chains, communication modules, and power supply units are fully compatible. TwinCAT project migration from TC2 to TC3 is required if the legacy CPU ran TwinCAT 2.

Q2: Can I retain my existing PROFIBUS field wiring after installing the CX2020-0121?
Yes. By adding an EL6731 PROFIBUS DP master terminal to the EtherCAT terminal chain, the CX2020-0121 can continue to communicate with all existing PROFIBUS DP slaves. No field wiring changes are required. The PROFIBUS GSD files for existing slaves are imported into the TwinCAT 3 project during commissioning.

Q3: What pre-shipment testing is performed on CX2020-0121 units?
All CX2020-0121 modules supplied by NINERMAS undergo a full functional test prior to dispatch, including power-on verification, EtherCAT master port enumeration, and TwinCAT runtime boot confirmation. Units are supplied with a 12-month warranty from the date of delivery. Test records are available upon request.

Q4: What is the typical lead time and stock availability?
NINERMAS maintains dedicated inventory of Beckhoff CX20xx series modules to support urgent retrofit and breakdown replacement requirements. Standard orders are dispatched within 1–3 business days. For large-quantity or long-term supply agreements, please contact our team directly to discuss scheduled delivery and reserved stock arrangements.