SEW-Eurodrive DFx Series Option Modules — DFI21B

Technical Dossier

Product Details And Specifications

SEW-Eurodrive DFx Series: Comprehensive Module Range and Technical Overview

The SEW-Eurodrive DFx series represents the standardized option module platform for the MOVIDRIVE MDX60B/61B and earlier MDX60A/61A frequency inverter families. These plug-in modules extend the base inverter with fieldbus communication, encoder feedback, safety functions, and I/O expansion capabilities. Deployed across global heavy industry — including petrochemical complexes, nuclear auxiliary systems, offshore platforms, and continuous-process refineries — the DFx platform is embedded in tens of thousands of drive installations worldwide. The modular slot architecture allows field engineers to reconfigure communication protocols or feedback systems without replacing the base drive unit, a critical advantage in facilities where unplanned downtime carries six-figure hourly costs. SEW-Eurodrive's manufacturing base in Bruchsal, Germany, combined with a global distribution network, established the DFx series as a de facto standard for European-designed process automation systems from the late 1990s through the 2010s.

The Evolution of DFx Architecture

The DFx option module concept was introduced alongside the MOVIDRIVE A series (MDX60A/61A) in the mid-1990s. First-generation modules — designated with the suffix A (e.g., DFI21A, DFE32A) — used a parallel backplane interface with 5V TTL logic levels and were limited to the physical slot dimensions of the MDX60A chassis. Communication speeds on fieldbus modules topped out at 12 Mbit/s (PROFIBUS-DP), which was adequate for the cyclic I/O polling architectures of that era.

With the introduction of the MOVIDRIVE B platform (MDX60B/61B) circa 2003, SEW-Eurodrive revised the option module interface to a higher-speed serial backplane bus, resulting in the B-suffix generation (e.g., DFI21B, DFE32B). Key architectural changes included: increased backplane data throughput, support for isochronous real-time (IRT) Ethernet protocols, expanded encoder signal conditioning for sin/cos and EnDat 2.1/2.2 interfaces, and integrated safe-state output logic for STO (Safe Torque Off) compliance under IEC 61800-5-2. The B-generation modules are not backward-compatible with MDX60A chassis due to the revised connector pinout and bus protocol.

By the mid-2010s, the MOVIDRIVE B platform entered its mature/sustaining phase. SEW-Eurodrive's current flagship — the MOVI-C MOVIDRIVE modular — uses a fundamentally different module ecosystem. As a result, the entire DFx series is now in a lifecycle sustaining / long-term maintenance phase: modules remain available as spare parts but are no longer subject to active feature development. For facilities operating MOVIDRIVE B drives, long-term maintenance sourcing from specialist distributors such as DriveKNMS is the primary strategy for extending asset life beyond OEM support windows.

DFx Full Catalog & Functionalities (SKU List)

Fieldbus Interface Modules

• DFI21B: INTERBUS fieldbus interface module for MOVIDRIVE B; supports INTERBUS remote bus and installation remote bus topologies.
• DFI11B: PROFIBUS-DP slave interface for MOVIDRIVE B; cyclic process data exchange up to 12 Mbit/s, supports PROFIsafe profile.
• DFE32B: PROFINET IO device module for MOVIDRIVE B; supports RT and IRT communication classes, 100 Mbit/s.
• DFE33B: EtherNet/IP adapter module for MOVIDRIVE B; CIP motion profile support, 100 Mbit/s full duplex.
• DFE24B: EtherCAT slave interface for MOVIDRIVE B; CoE (CANopen over EtherCAT) object dictionary, distributed clocks support.
• DFS21B: SERCOS II interface module for MOVIDRIVE B; fiber-optic ring topology, 2/4/8/16 Mbit/s selectable baud rate.
• DFS11B: CANopen slave module for MOVIDRIVE B; DS402 drive profile, 1 Mbit/s maximum bus speed.
• DFR21B: DeviceNet slave adapter for MOVIDRIVE B; Group 2 only server, 500 kbit/s maximum.

Encoder Feedback Modules

• DFE11B: Incremental encoder input module for MOVIDRIVE B; HTL/TTL signal conditioning, up to 300 kHz input frequency.
• DFE13B: Sin/cos encoder and resolver interface for MOVIDRIVE B; 1 Vpp sin/cos input, resolver excitation output.
• DFP21B: Absolute encoder interface (SSI/EnDat 2.1) for MOVIDRIVE B; supports Heidenhain EnDat and Stegmann Hiperface protocols.
• DFP11B: Hiperface absolute encoder module for MOVIDRIVE B; single-cable feedback interface, 32-bit position resolution.

I/O Extension Modules

• DFD11B: Digital I/O extension module for MOVIDRIVE B; 4 DI / 4 DO, 24 VDC logic, screw terminal connection.

Legacy A-Generation Modules (MOVIDRIVE A compatible)

• DFI21A: INTERBUS interface for MOVIDRIVE A (MDX60A/61A); parallel backplane interface, not compatible with B-chassis.
• DFE32A: PROFINET IO module for MOVIDRIVE A; 100 Mbit/s, legacy RT class only.
• DFE33A: EtherNet/IP module for MOVIDRIVE A; legacy adapter, no CIP motion support.
• DFD11A: Digital I/O extension for MOVIDRIVE A; 4 DI / 4 DO, parallel bus interface.

Sourcing Hard-to-Find & Obsolete DFx Series Parts

DriveKNMS maintains a dedicated inventory program for MOVIDRIVE B option modules, with particular focus on fieldbus interface variants that are no longer stocked by regional SEW-Eurodrive distributors. The DFI21B (INTERBUS), DFR21B (DeviceNet), and DFS21B (SERCOS II) are among the highest-demand obsolete modules, as the underlying fieldbus protocols have been superseded in new installations but remain active in legacy plant networks that cannot be economically migrated.

Our sourcing process for DFx modules includes: verification of module revision level against the target MOVIDRIVE B firmware version, inspection of the backplane connector for pin deformation or oxidation, and functional pre-test on a live MOVIDRIVE B test bench prior to shipment. Modules sourced from decommissioned equipment undergo a full refurbishment cycle before being offered as tested-used stock. New-old-stock (NOS) units with original SEW-Eurodrive packaging are catalogued separately and carry a 12-month warranty.

Quality Control for the DFx Range

The DFx module backplane interface operates at 3.3V logic with a proprietary serial protocol. Standard bench multimeter testing is insufficient to validate module functionality. DriveKNMS employs the following test protocol for all DFx units:

• Backplane continuity test: All 40 backplane connector pins verified for continuity and isolation resistance (>10 MΩ between signal and ground planes).
• Live insertion test: Module inserted into a powered MOVIDRIVE B test unit; drive firmware module recognition confirmed via MOVITOOLS MotionStudio diagnostic software.
• Fieldbus loopback test: For communication modules (DFI21B, DFE32B, DFE33B, etc.), a protocol-specific loopback or master simulator is connected to verify cyclic data exchange at rated bus speed.
• Encoder signal verification: For feedback modules (DFE11B, DFE13B, DFP21B), encoder simulation signals are injected and position/speed readback is confirmed within ±1 LSB tolerance.
• Thermal soak: Units operated at 45°C ambient for 2 hours under cyclic load to screen for latent solder joint failures.