Siemens 6SL3351-6GH35-8AB3 Retrofit-Compatible Drive for Legacy Systems

Siemens 6SL3351-6GH35-8AB3 Retrofit-Compatible Drive for Legacy Systems

The Siemens 6SL3351-6GH35-8AB3 is a high-performance servo drive module designed for the SINAMICS S120 platform, widely deployed across precision manufacturing, automotive assembly lines, packaging machinery, and process automation facilities. As production environments age and original equipment manufacturers discontinue support for legacy drive configurations, the 6SL3351-6GH35-8AB3 has become a critical retrofit and replacement component for engineers tasked with modernizing existing control architectures without full system overhauls.

This module is engineered to integrate seamlessly into existing S120 booksize and chassis installations, making it an ideal candidate for facilities that need to extend the operational life of their automation infrastructure while avoiding the cost and downtime associated with complete platform migration. Whether you are replacing a failed unit on an active production line or proactively upgrading aging drive hardware ahead of a planned maintenance window, the 6SL3351-6GH35-8AB3 delivers the performance and compatibility required for a smooth transition.

Upgrade Compatibility Table

Retrofit Planning for Existing Automation Systems

Successful integration of the 6SL3351-6GH35-8AB3 into a legacy system begins with a thorough pre-retrofit assessment. Engineers must verify the existing DC bus voltage and power supply capacity before installation. The S120 system’s Active Line Module or Smart Line Module — such as the 6SL3130 series — must be confirmed capable of supporting the additional drive load without exceeding rated output current. In many retrofit scenarios, the existing 6SL3100-series line filter and reactor assemblies can be retained, reducing material costs and installation complexity.

Terminal wiring compatibility is a key checkpoint. The 6SL3351-6GH35-8AB3 uses standard S120 booksize terminal layouts, but engineers should cross-reference the existing wiring diagrams against the replacement module’s terminal assignment to confirm signal wire routing for enable inputs, fault outputs, and motor feedback connections. Where legacy encoder cables are in use, compatibility with the DRIVE-CLiQ interface or SMC (Sensor Module Cabinet-Mounted) units such as the 6SL3055-0AA00-5BA3 should be verified to avoid signal conversion issues.

Backplane and rack slot assignments must also be confirmed. In multi-axis S120 configurations, the module address and axis assignment stored in the Control Unit — typically a CU320-2 DP or CU320-2 PN — must be updated to reflect the new hardware. This is performed through the STARTER commissioning software or Startdrive within TIA Portal. If the existing project file is available, the hardware configuration can be updated with minimal reprogramming effort. Where project files have been lost, a drive upload function can recover parameter sets from the existing Control Unit memory.

HMI screen mappings linked to drive status words, fault codes, and speed references should be reviewed in parallel. Siemens SIMATIC HMI panels connected via PROFIBUS DP or PROFINET IO may require tag updates if the new module occupies a different logical address. Coordination between the drive commissioning engineer and the HMI programmer is recommended to prevent screen display errors during the first power-up sequence.

For installations involving communication protocol migration — for example, transitioning from PROFIBUS DP to PROFINET IO — the 6SL3351-6GH35-8AB3 supports both interfaces, allowing a phased migration approach. The existing PROFIBUS network can remain operational during the transition period while PROFINET infrastructure is installed in parallel, minimizing disruption to production schedules.

I/O expansion requirements should also be assessed. If the retrofit involves adding new axis control or expanding digital I/O capacity, supplementary Terminal Modules such as the TM31 (6SL3055-0AA00-3AA1) or TM41 can be added to the S120 rack without replacing the core drive module. This modular approach allows incremental system expansion while preserving the existing control logic and parameter structure.

Downtime Control During System Migration

Minimizing production downtime during a drive replacement is a primary concern for plant engineers and maintenance managers. The 6SL3351-6GH35-8AB3 supports a structured hot-swap preparation process that allows pre-configuration of the replacement module offline before the scheduled maintenance window. Using the STARTER software or Startdrive, the replacement drive can be pre-loaded with the existing parameter set exported from the Control Unit, reducing on-site commissioning time to a final verification and test run.

Before initiating the physical swap, the existing drive’s parameter set — including speed controller gains, torque limits, encoder configuration, and safety function settings — should be backed up to a memory card or PC. The S120 Control Unit supports parameter backup via the integrated CF card slot, enabling rapid restoration in the event of an unexpected fault during commissioning.

During the physical installation, the DC bus must be fully discharged and isolated before removing the existing module. The 6SL3351-6GH35-8AB3 slots into the existing booksize rack without mechanical modification, and the DRIVE-CLiQ topology is automatically recognized by the Control Unit upon power-up. A full function test — including jog mode operation, speed reference tracking, fault acknowledgment, and safety function verification — should be completed before returning the axis to automatic production mode. With proper preparation, total downtime for a single-axis replacement can typically be contained within a planned four-hour maintenance window.

Retrofit Support FAQ

Q: Is the 6SL3351-6GH35-8AB3 a direct drop-in replacement for my existing S120 drive module?
A: In most S120 booksize configurations, yes. The module uses the same mechanical form factor, DC bus connection, and DRIVE-CLiQ interface as equivalent S120 servo drive modules. Minor parameter adjustments may be required depending on the specific axis configuration and firmware version in use.

Q: What commissioning steps are required after installation?
A: After physical installation, connect the module to the Control Unit via DRIVE-CLiQ and power up the system. The Control Unit will automatically detect the new module. Load the pre-backed-up parameter set using STARTER or Startdrive, verify encoder feedback signals, and perform a jog test before returning to automatic mode. Full commissioning typically takes two to four hours for a single axis.

Q: Has the unit been tested before shipment?
A: Yes. All units supplied by NINERMAS undergo pre-shipment functional testing to verify power stage integrity, communication interface operation, and parameter upload/download capability. A test report is available upon request.

Q: What warranty and supply support is provided?
A: NINERMAS provides a 12-month warranty on all supplied units. We maintain stock inventory to support urgent replacement requirements and can provide expedited shipment for critical production line breakdowns. Contact our technical team for availability confirmation and lead time.