Siemens 1FK7042-2AF71-1RG0 Replacement for SIMOTICS S

Product Overview

Siemens 1FK7042-2AF71-1RG0 Replacement for SIMOTICS S: Smooth Transition & Legacy System Compatibility

Migrating from an aging servo drive system to a modern, high-performance replacement is one of the most critical decisions in industrial control system modernization. The Siemens 1FK7042-2AF71-1RG0 — a compact permanent-magnet synchronous servo motor from the SIMOTICS S-1FK7 series — is a proven drop-in upgrade solution for facilities running discontinued or end-of-life Siemens servo axes. Whether your plant is retiring legacy 1FT6 or early-generation 1FK6 motors, or replacing a failed unit in a SINUMERIK or SINAMICS-controlled machine tool, this motor delivers the dimensional compatibility, encoder interface, and torque characteristics needed for a seamless retrofit.

The 1FK7042-2AF71-1RG0 is rated for a stall torque of 4.0 Nm with a natural-cooled (self-ventilated) design, making it suitable for compact control cabinet installations where forced-air cooling is impractical. Its DRIVE-CLiQ encoder interface integrates directly with SINAMICS S120 drive modules — including the CU320-2 Control Unit, ALM/SLM power modules, and Motor Modules in booksize or chassis format — eliminating the need for separate encoder evaluation cards that older resolver-based motors required. For sites still operating SINAMICS S110 or SIMODRIVE 611 systems, an encoder adapter or drive firmware upgrade may be required; our technical team can advise on the correct transition path before shipment.

Physically, the 1FK7042 frame size aligns with the standard IEC flange dimensions used across the 1FK7 and 1FK6 families, meaning existing motor mounting brackets, coupling hubs, and shaft keyways in most machine tool axes can be reused without machining. The motor’s power connector and signal connector pinout follows the Siemens standard for the 1FK7 series, so existing motor cables — including pre-assembled MOTION-CONNECT 500 or MOTION-CONNECT 800PLUS cable sets — are typically reusable if they are in good condition, reducing rewiring time during the maintenance window.

For CNC machine tool retrofits running SINUMERIK 840D sl or SINUMERIK 828D, the motor data set (MDS) for the 1FK7042-2AF71-1RG0 is available in the SINAMICS drive database and can be loaded via STARTER or Startdrive commissioning software. This eliminates manual parameter entry and reduces the risk of commissioning errors. Sites using SIMATIC S7-1500T or S7-1200 motion controllers with PROFINET-based axis control will find that the DRIVE-CLiQ topology auto-identifies the motor, further accelerating first-motion validation after replacement.

In distributed I/O architectures where the servo axis is coordinated with ET 200SP or ET 200MP I/O stations over PROFINET, the replacement of this motor requires no changes to the PLC program or I/O mapping — only the drive parameterization needs to be updated to reflect the new motor data. Similarly, safety-integrated functions such as Safe Torque Off (STO) and Safe Stop 1 (SS1), wired through the drive’s F-DI terminals or via PROFIsafe, remain fully compatible with the 1FK7042-2AF71-1RG0 without hardware modification.

For facilities managing spare parts across multiple machine lines, this motor is also a compatible replacement for axes previously equipped with 1FK7042-2AC71 or 1FK7042-2AK71 variants, subject to encoder type and holding brake configuration verification. Our pre-shipment inspection includes a full electrical test, encoder signal verification, and insulation resistance check, ensuring the unit arrives ready for installation.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful servo axis migration rarely involves the motor alone. When replacing the 1FK7042-2AF71-1RG0 in a SINAMICS S120 system, the associated SINAMICS S120 Motor Module (6SL3120 series) should be inspected for firmware compatibility — older booksize Motor Modules running firmware below V4.7 may require an update to correctly identify the DRIVE-CLiQ motor data. If the existing SINAMICS S120 Control Unit CU320-2 PN is also being replaced as part of a broader modernization, the new CU must be configured with the correct drive object topology before the motor is powered.

For the power supply side, the SINAMICS S120 Active Line Module (ALM) or Smart Line Module (SLM) feeding the DC bus should be verified for adequate power rating when adding or replacing axes. In cabinet-level retrofits, SITOP PSU8600 or SITOP modular 24V DC power supplies are commonly used to power the control-side components including the CU320-2 and ET 200SP I/O stations. Ensuring stable 24V DC supply quality is a prerequisite for reliable DRIVE-CLiQ communication and encoder signal integrity.

Where the machine uses a SINUMERIK 840D sl NCU as the motion controller, the NX10.3 or NX15.3 expansion modules connected via DRIVE-CLiQ must also be checked for axis slot availability before adding the replacement motor to the topology. For standalone servo applications controlled by a SIMATIC S7-1500T with the S7-1500 Motion Control technology object, the axis configuration in TIA Portal must be updated to reference the new motor’s rated data after replacement. Pre-tested MOTION-CONNECT 800PLUS power cables and signal cables in the correct length and connector variant for the 1FK7042 frame are available and can be shipped together with the motor to minimize procurement lead time.

Retrofit Guidance FAQ

Q: Can I reuse my existing motor cable from a 1FK6 motor?
A: In most cases, yes — if the cable uses the standard Siemens 1FK7-compatible connector on the motor end and is in good condition. Verify the power connector size (size 1 for 1FK7042) and signal connector type (DRIVE-CLiQ M12 or rectangular) match your existing cable assembly before reuse.

Q: Do I need to re-enter motor parameters after replacement?
A: No. The DRIVE-CLiQ interface transmits the motor nameplate data automatically to the SINAMICS drive. After connecting the motor and powering the drive, run a “Download to Target System” in STARTER or Startdrive to confirm the motor data set is correctly loaded.

Q: Is the holding brake wiring compatible with my existing brake relay circuit?
A: The 1FK7042-2AF71-1RG0 uses a standard 24V DC spring-applied holding brake. If your existing brake control relay and wiring are rated for 24V DC and the correct current draw, they are directly reusable. Verify the brake release current specification in the motor datasheet before connection.

Q: Will my PROFINET network configuration need to change?
A: No. The PROFINET device name and IP address are assigned to the SINAMICS drive, not the motor. Replacing the motor does not affect the PROFINET topology or PLC program.

Q: What if my machine uses an older SIMODRIVE 611 drive?
A: The 1FK7042-2AF71-1RG0 with DRIVE-CLiQ encoder is not directly compatible with SIMODRIVE 611 without an encoder adapter module. In this scenario, we recommend evaluating a parallel drive upgrade to SINAMICS S120 to fully leverage the motor’s capabilities. Contact us for a system-level migration assessment.

Warranty Assurance

Every Siemens 1FK7042-2AF71-1RG0 unit shipped by TOPNLMS is covered by a 12-month replacement warranty from the date of delivery. Prior to shipment, each unit undergoes a structured pre-delivery inspection including: winding resistance measurement, insulation resistance test (Megger test at 500V DC), DRIVE-CLiQ encoder communication verification, holding brake engagement and release test, and visual inspection of shaft, flange, and connectors. Units that do not pass all inspection criteria are quarantined and not shipped.

In the event of a warranty claim, TOPNLMS provides a replacement unit dispatch within 5 business days of claim confirmation, with no requirement to return the defective unit before the replacement is shipped for critical production environments. Our after-sales response team is reachable via email and phone during business hours (GMT+8), and technical support for installation and commissioning questions is available at no additional charge during the warranty period.

Stock is maintained in Xiamen, China, with DHL Express, FedEx International Priority, and sea freight options available depending on urgency and destination. Export documentation including commercial invoice, packing list, and certificate of origin is prepared for all international shipments.