Siemens 6SE7035-1EJ84-1BH0 Encoder Option Board – SIMOVERT MASTERDRIVES MC

Siemens 6SE7035-1EJ84-1BH0 Absolute Value Encoder Option Board — Closed-Loop Positioning Interface for SIMOVERT MASTERDRIVES MC

The Siemens 6SE7035-1EJ84-1BH0 is a plug-in option board engineered for the SIMOVERT MASTERDRIVES MC (Motion Control) drive platform. Its primary function is to extend the drive’s feedback acquisition capability by accepting absolute position data from high-resolution encoders via SSI (Synchronous Serial Interface) or EnDat 2.1 protocols. Unlike incremental encoders that require a reference run after each power cycle, absolute encoders connected through this board deliver immediate, unambiguous position values upon energization — a critical requirement in applications where homing cycles are mechanically impractical or time-prohibitive.

Within the MASTERDRIVES MC control loop, the 6SE7035-1EJ84-1BH0 sits between the encoder hardware and the drive’s CUMC (Compact Unit Motion Control) processor. It conditions the raw serial position stream, performs protocol decoding, and presents a normalized position word to the drive’s internal position controller at the servo cycle rate. This architecture offloads encoder communication overhead from the main CPU, preserving deterministic cycle time for the position and speed regulation loops.

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Technical Parameters

Hardware Logical Analysis

The 6SE7035-1EJ84-1BH0 implements a dedicated encoder front-end ASIC that handles the time-critical SSI clock generation and data capture independently of the CUMC processor’s main execution thread. The SSI protocol requires precise clock-to-data timing margins — typically a setup time of ≥ 0.5 µs and a hold time of ≥ 0.1 µs at the encoder output — and any jitter in clock generation directly corrupts the received position word. By delegating this function to a hardware state machine on the option board, the design eliminates software-induced jitter entirely.

The RS-422 differential signaling layer provides inherent common-mode noise rejection of ±7 V, which is essential in drive cabinets where PWM switching transients generate broadband electromagnetic interference across the 150 kHz – 30 MHz spectrum. The optocoupler isolation stage adds a further galvanic barrier rated at 500 V AC (1 minute), preventing ground loop currents — a common failure mode in long encoder cable runs — from corrupting the logic supply rail of the drive’s control electronics.

For EnDat 2.1 operation, the board supports bidirectional communication: in addition to reading position data, it can issue parameter read/write commands to the encoder’s internal memory (MEM). This allows the drive to retrieve encoder-specific data such as manufacturer ID, serial number, and calibration offsets during initialization, enabling automatic encoder identification without manual parameter entry. The EnDat command set is executed over the same differential pair used for position data, with the board managing the half-duplex arbitration logic in hardware.

The board’s power supply section includes a dedicated DC-DC converter that generates the encoder supply voltage (5 V or 24 V, selectable) from the 5 V backplane rail. A current-limiting circuit with a 300 mA threshold protects both the option board and the connected encoder from wiring faults. The converter operates at a fixed switching frequency above 200 kHz, placing its fundamental harmonic well above the SSI clock frequency range and preventing interference with the data acquisition path.

From an EMC design standpoint, the PCB layout employs a split ground plane strategy: the encoder-side analog ground and the backplane digital ground are connected at a single star point adjacent to the isolation barrier. This topology prevents high-frequency digital switching currents from flowing through the analog ground return path, maintaining signal integrity on the differential encoder lines even in the presence of adjacent IGBT gate drive switching events.

System Integration Benefits

• Immediate absolute position on power-up: Eliminates reference run sequences, reducing machine restart time from minutes to seconds in applications such as gantry systems and multi-axis machining centers.
• Deterministic servo cycle preservation: Hardware-offloaded encoder communication ensures the CUMC’s 1.7 ms position control cycle is not extended by encoder polling overhead, maintaining consistent loop bandwidth.
• Automatic encoder identification via EnDat MEM: Drive parameters P130x (encoder type) and P131x (resolution) are populated automatically during commissioning, reducing parameter entry errors and shortening startup time.
• Galvanic isolation for long cable runs: The 500 V AC isolation barrier supports encoder cable lengths up to 100 m (SSI) without ground loop interference, enabling distributed machine architectures.
• Dual-protocol flexibility: A single hardware variant supports both SSI and EnDat 2.1 encoders, reducing spare parts inventory and simplifying procurement for mixed-encoder installations.
• Integrated encoder supply with fault protection: The on-board 300 mA current-limited supply eliminates the need for an external encoder power supply unit, reducing panel wiring complexity and potential failure points.
• Enhanced diagnostic transparency: The CUMC can read encoder status bits (alarm, warning, busy) via the EnDat channel and map them to drive fault codes F0xx, providing encoder-level diagnostics visible in the drive’s fault buffer without additional hardware.
• Compatibility with PROFIBUS DP and SIMATIC S7 supervisory systems: Position data acquired by the option board is accessible via the drive’s PROFIBUS process data channel (PZD), allowing the S7 PLC to read absolute position at each DP cycle without additional fieldbus nodes.
• Plug-in form factor with no drive firmware modification: The board is recognized by the CUMC via the option slot identification resistor network; no firmware update is required for drives running firmware version ≥ 3.1.
• Reduced mechanical wear on reference switches: By eliminating homing cycles, the board extends the service life of limit switches and proximity sensors used as reference points in conventional incremental encoder setups.

Quality Assurance & Global Logistics

Every Siemens 6SE7035-1EJ84-1BH0 unit dispatched from our Xiamen, China facility is a genuine Siemens-manufactured component sourced through verified industrial supply channels. Each unit undergoes incoming inspection covering label authenticity, housing integrity, connector pin condition, and serial number traceability against Siemens production records. Functional verification is performed on a dedicated MASTERDRIVES MC test bench, confirming SSI clock generation, data capture, and encoder supply output within factory-specified tolerances before packaging.

Packaging follows anti-static ESD protocols (ANSI/ESD S20.20): the board is placed in a conductive foam tray inside a shielded bag, then packed in a rigid corrugated carton with ≥ 50 mm foam cushioning on all six faces. This packaging standard is maintained regardless of shipment mode.

Logistics from Xiamen operate on the following service levels:

• Express Air (DHL / FedEx / UPS): 3 – 5 business days to Europe and North America; 2 – 4 business days to Southeast Asia.
• Economy Air: 7 – 12 business days, suitable for non-urgent procurement with cost sensitivity.
• Sea Freight (LCL/FCL): Available for bulk orders; transit times 18 – 35 days depending on destination port.
• Export documentation: Commercial invoice, packing list, certificate of origin (CO), and HS code 8537.10 customs declaration provided as standard. CITES, REACH, and RoHS compliance documentation available on request.
• In-stock items: Ship within 1 – 2 business days of payment confirmation.

A 12-month warranty against manufacturing defects is provided from the date of shipment. Warranty claims are processed with a target response time of 48 hours. Replacement units are dispatched via express freight at no additional cost for confirmed defective items within the warranty period.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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