FAGOR MCS-20L Retrofit-Compatible Servo Driver for Legacy Systems

FAGOR MCS-20L Retrofit-Compatible Servo Driver for Legacy Systems

The FAGOR MCS-20L is a high-performance servo driver from FAGOR’s MCS Series, engineered for precision motion control in CNC machine tools, automated production lines, and legacy control cabinet installations. As FAGOR’s industrial automation division has undergone significant restructuring, the MCS-20L has become a critical spare part for facilities operating aging FAGOR-based CNC platforms — including FAGOR 8025, 8030, 8035, and 8055 CNC controller families — where maintaining servo loop integrity is essential to continued production.

NINERMAS maintains verified stock of the MCS-20L to support retrofit engineers, maintenance teams, and procurement specialists who require a reliable, tested replacement for failed or end-of-life servo amplifier modules. Each unit is inspected, function-tested, and shipped with a 12-month warranty, ensuring your retrofit project proceeds with confidence and minimal downtime risk.

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Retrofit Planning for Existing Automation Systems

Replacing a failed FAGOR MCS-20L in a live production environment demands careful pre-planning across multiple system layers. The servo driver does not operate in isolation — it is tightly integrated with the CNC controller, the power supply module, the motor feedback chain, and the machine’s PLC logic. A structured retrofit approach significantly reduces the risk of extended downtime and commissioning errors.

Power Supply Verification: Before installing the MCS-20L, confirm that the existing FAGOR PS-25 or FAGOR PS-65 DC bus power supply has sufficient current headroom to support the replacement axis. In multi-axis cabinets where several MCS-series drives share a common DC bus, a single failed drive may have been masking an overloaded supply. Measure bus voltage under load and compare against the MCS-20L’s minimum operating threshold.

Terminal Wiring and Connector Mapping: The MCS-20L uses a defined terminal layout for power input (L1/L2/L3), motor output (U/V/W), brake resistor, and control signal connectors. When replacing a unit that has been in service for years, terminal screws may be corroded or torqued incorrectly. Re-torque all connections to specification and inspect the motor cable shield grounding at the drive end. For systems using the FAGOR FL-series feedback cables, inspect the D-sub connector pins for fretting corrosion before reconnection.

Backplane and Rack Address Configuration: In FAGOR MCS rack installations, each drive module occupies a defined slot address that corresponds to its axis assignment in the CNC controller. When inserting the replacement MCS-20L, verify the slot position matches the original axis (X, Y, Z, or spindle). Incorrect slot placement will cause the FAGOR 8035 or 8055 CNC to generate axis configuration faults at power-up. If the rack also houses a FAGOR MCS-14L (lower-current axis) or a FAGOR MCS-25L (higher-current axis), confirm that the bus termination resistor is correctly positioned at the last module in the chain.

Encoder and Feedback Chain Integrity: The MCS-20L supports both TTL incremental encoders and sinusoidal encoders. Before commissioning, use an oscilloscope or the FAGOR WinDDS diagnostic tool to verify encoder signal quality — particularly A/B/Z channel amplitude and differential balance. In older machines, the FAGOR encoder extension cable or the motor-side encoder connector may have developed intermittent faults that were previously attributed to the drive itself. Replacing the drive without inspecting the feedback chain is a common source of repeat failures.

PLC and HMI Program Compatibility: In integrated FAGOR CNC systems, the machine PLC program (written in FAGOR’s internal PLC language or IEC 61131-3) may reference axis-specific drive fault codes, ready signals, and enable outputs. After installing the MCS-20L, verify that the PLC ladder logic correctly maps the drive’s digital I/O — particularly the drive-ready (DRDY) and drive-fault (DFLTY) signals — to the machine’s safety interlock chain. If the machine uses a FAGOR HMI panel (such as the FAGOR 8055i or 8065 operator panel), confirm that axis status displays and alarm messages are functioning correctly after the swap.

Communication Link Validation: For SERCOS-based installations, the MCS-20L must be assigned the correct SERCOS node address (IDN S-0-0096) before the CNC controller can establish communication. Use the WinDDS commissioning software to set the node address, confirm the SERCOS ring is closed (no open-circuit faults), and verify that the fiber-optic SERCOS cable between the CNC controller and the first drive in the ring is undamaged. In systems where the SERCOS ring also passes through a FAGOR I/O expansion module or a FAGOR remote I/O node, inspect all fiber connectors for contamination.

Signal Isolation and Grounding: In retrofit scenarios where the MCS-20L is being installed alongside third-party drives or in a mixed-vendor cabinet, consider adding a signal isolator on analog reference inputs (±10V command) to prevent ground loop interference. Proper PE (protective earth) bonding between the drive chassis, the motor cable shield, and the cabinet backplane is critical for EMC compliance and for protecting the drive’s internal DSP from conducted noise.

Pre-Shipment Testing and Inventory: Every FAGOR MCS-20L supplied by NINERMAS undergoes functional testing prior to dispatch. For projects requiring multiple axes, we recommend sourcing a complete set — including any required FAGOR MCS-10L modules for auxiliary axes — in a single order to ensure batch consistency and reduce lead-time risk for future failures.

Downtime Control During System Migration

Unplanned servo drive failure in a CNC machining center or automated assembly line can halt production within minutes. The key to minimizing downtime during an MCS-20L replacement is preparation: have the replacement unit on-site before decommissioning the failed drive, and complete all parameter documentation while the machine is still partially operational.

Parameter Backup Before Power-Down: If the CNC controller is still communicating (even with a degraded axis), use the FAGOR WinDDS software or the CNC’s built-in parameter backup function to export all drive parameters — including current loop gains (KP, KI), velocity loop gains, position loop gains, motor data (rated current, pole pairs, encoder resolution), and any application-specific tuning offsets. Store this backup on a USB drive and retain a printed copy in the machine’s maintenance logbook. This data is essential for rapid recommissioning of the replacement MCS-20L.

Staged Replacement Procedure: Power down the machine following the correct FAGOR shutdown sequence (disable servo enables → disable CNC → cut DC bus → cut AC mains). Allow the DC bus capacitors to discharge fully (minimum 5 minutes, or until the bus voltage indicator LED extinguishes) before opening the cabinet. Label all connectors on the failed drive before disconnection. Install the replacement MCS-20L, reconnect all cables in reverse order, and perform a visual inspection before power-up.

Commissioning and Test Cuts: After restoring power, use WinDDS to load the backed-up parameters into the replacement drive. Perform a motor identification run if the drive prompts for it (common when replacing with a unit from a different firmware revision). Run the axis through its full travel range at reduced feedrate (10–20% of maximum) before returning to production speed. Verify that position error (following error) remains within the CNC’s tolerance window and that no thermal or overcurrent alarms appear during the test cycle. Only after a successful test cut should the machine be returned to full production.

Spare Parts Lifecycle Planning: Given the discontinued status of the FAGOR MCS series, we recommend that facilities operating multiple FAGOR-based machines establish a strategic spare parts inventory covering at least one MCS-20L per machine, along with critical companion components such as the FAGOR PS-series power supply and FAGOR encoder cables. NINERMAS offers long-term stock commitment programs for high-priority SKUs, enabling procurement teams to secure supply for 12–36 month horizons without capital exposure risk.

Retrofit Support FAQ

Q1: Is the FAGOR MCS-20L a direct drop-in replacement for a failed unit on my FAGOR 8035 CNC machine?
Yes, in the vast majority of cases. The MCS-20L is slot-compatible with the original FAGOR MCS rack and uses the same connector layout. However, you should verify the firmware revision of the replacement unit against your CNC controller’s compatibility matrix using WinDDS. If a firmware update is required, NINERMAS can advise on the correct revision for your specific CNC model.

Q2: What wiring checks should I perform before powering up the replacement MCS-20L?
Verify motor phase wiring (U/V/W) matches the original connection — incorrect phase order will cause the motor to run in reverse or trigger overcurrent faults. Confirm encoder cable shield is grounded at the drive end only (not at the motor end) to avoid ground loops. Check that the brake resistor connection (if used) is intact and that the resistor’s thermal switch is wired into the drive’s fault input. Finally, confirm DC bus polarity on the power supply connection.

Q3: Can the MCS-20L be used in a system where I am migrating from SERCOS I to a newer communication protocol?
The MCS-20L natively supports SERCOS I and SERCOS II. Migration to SERCOS III or EtherCAT requires a CNC controller upgrade (such as the FAGOR 8065 platform) and is not supported by the MCS-20L hardware. If your migration plan involves a protocol change, contact NINERMAS to discuss compatible servo drive alternatives that support your target communication standard while maintaining mechanical and electrical compatibility with your existing motor and feedback hardware.

Q4: What does the 12-month warranty cover, and how is it supported?
All FAGOR MCS-20L units supplied by NINERMAS carry a 12-month warranty covering manufacturing defects and functional failures under normal operating conditions. Each unit is function-tested prior to shipment — including DC bus charging, SERCOS communication handshake, and output stage verification. In the event of a warranty claim, NINERMAS provides advance replacement support to minimize production downtime. Contact our technical team at sale@ninermas.com or +0086 187 5021 5667 to initiate a warranty assessment.