Bosch Rexroth VT-HACD-1-12/V0/1-0-0 R978005518 Hydraulic Axis Controller – VT-HACD Series

Bosch Rexroth VT-HACD-1-12/V0/1-0-0 R978005518 — Hydraulic Axis Controller Card for Closed-Loop Electrohydraulic Drives

The VT-HACD-1-12/V0/1-0-0 (Rexroth material number R978005518) is a single-axis digital hydraulic axis controller card designed for closed-loop position, velocity, and force control of electrohydraulic servo and proportional valve systems. Manufactured by Bosch Rexroth AG in Germany, this card belongs to the VT-HACD product family — a line of plug-in amplifier and controller cards engineered for integration into Rexroth’s VT-HNC100 and compatible rack-mount control platforms. The module executes real-time PID-based control algorithms at the hardware level, decoupling axis dynamics from the host PLC scan cycle and delivering deterministic closed-loop response independent of fieldbus latency.

In electrohydraulic motion systems, the controller card occupies the critical interface layer between the digital command signal (position setpoint from PLC or CNC) and the analog valve drive signal. The VT-HACD-1-12 processes encoder or LVDT position feedback, computes the control deviation, applies configurable PID gain parameters, and outputs a ±10 V or current-loop command to the proportional or servo valve amplifier stage. This architecture ensures that axis response time is governed by the hydraulic bandwidth of the actuator-valve system — not by PLC cycle time or communication overhead.

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Technical Parameters

Hardware Logical Analysis

The VT-HACD-1-12 implements a fully digital control pipeline on a dedicated DSP/FPGA substrate, separating the real-time control execution plane from the communication and parameterization plane. This architectural separation is fundamental to achieving deterministic axis response in hydraulic systems, where valve spool dynamics and fluid compressibility introduce phase lag that must be compensated within a tight timing budget.

Closed-Loop Execution Architecture: The control loop runs at a fixed hardware interrupt rate (≤ 1 ms), independent of any fieldbus communication cycle. Position feedback from the encoder or LVDT is sampled synchronously with the control interrupt, eliminating jitter-induced quantization error in the velocity estimate derived from position differentiation. The PID computation — including derivative filtering, integral anti-windup, and output clamping — executes within the same interrupt context, ensuring that the valve command signal is updated within a bounded, repeatable time window after each feedback sample.

EMC Design: The card employs differential signal reception on all analog inputs, with common-mode rejection ratios (CMRR) exceeding 60 dB across the industrial frequency band. Encoder input lines are terminated with matched impedance to suppress reflections on long cable runs. The analog output stage uses an isolated DAC with optocoupler-based ground isolation between the digital control domain and the valve amplifier output, preventing ground loop currents from introducing offset errors into the valve command signal — a critical requirement in hydraulic press and injection molding applications where valve null offset directly translates to actuator drift.

Ramp and Limit Supervision: Hardware-level ramp generators with configurable acceleration and deceleration profiles prevent step-change commands from exciting hydraulic resonance modes. Independently configurable software travel limits and velocity limits are enforced within the control card firmware, providing a secondary protection layer that operates even if the host PLC fails to enforce motion boundaries.

Feedforward Compensation: The velocity feedforward path allows the controller to pre-compensate for the known valve flow gain, reducing the position error during constant-velocity traversal without requiring high proportional gain — which would otherwise amplify noise and reduce stability margins in high-inertia hydraulic loads.

System Integration Benefits

• Deterministic Axis Response Independent of PLC Scan Time: The 1 ms hardware control cycle decouples hydraulic axis dynamics from PLC scan variability (typically 5–50 ms), enabling stable closed-loop bandwidth that would be unachievable if the control algorithm ran in the PLC task.
• Direct Compatibility with Rexroth Servo and Proportional Valves: The ±10 V analog output interfaces natively with Rexroth 4WRPH, 4WRKE, and proportional directional valve amplifiers without additional signal conditioning hardware.
• Multi-Mode Feedback Acceptance: Support for incremental encoder, SSI absolute encoder, and LVDT/RVDT inputs allows the same controller card to be deployed across different actuator types — hydraulic cylinders with magnetostrictive linear encoders, rotary hydraulic motors with shaft encoders, and servo-hydraulic test rigs with LVDT displacement transducers.
• Integrated Diagnostic Transparency: The card exposes real-time process values (actual position, velocity, control deviation, valve command) via the parameterization interface, enabling commissioning engineers to observe closed-loop behavior without external measurement equipment.
• Configurable PID Gain Sets: Multiple gain parameter sets can be stored and switched under program control, supporting applications where load characteristics change between operating phases (e.g., different tooling masses in hydraulic presses).
• Anti-Windup and Output Limiting: Integral anti-windup prevents integrator saturation during actuator travel limit contact or valve saturation, ensuring smooth recovery when the axis returns to the controllable range — a common failure mode in poorly configured hydraulic position controllers.
• PROFIBUS-DP Integration: In PROFIBUS-equipped variants, the card accepts position setpoints and reports actual values directly on the fieldbus, reducing wiring complexity and enabling coordinated multi-axis motion sequencing from a single PLC program block.
• Rack-Based Modularity: The plug-in card format allows field replacement without rewiring — the rack backplane carries all power and signal connections, reducing mean time to repair (MTTR) in production environments where hydraulic press downtime carries high cost.

Quality Assurance & Global Logistics

Every VT-HACD-1-12/V0/1-0-0 R978005518 unit offered through siemensplc.com is sourced as genuine Bosch Rexroth original hardware. Units are procured through documented industrial supply channels and subjected to incoming inspection prior to listing: physical marking verification against Rexroth label standards, connector pin integrity check, and visual PCB examination for evidence of rework or counterfeit substitution. Original Rexroth packaging is preserved where available; units in secondary packaging are clearly identified and priced accordingly.

Shipments originate from our warehouse in Xiamen, China — a major logistics hub with direct access to international freight forwarders serving Europe, Southeast Asia, the Middle East, and the Americas. Standard export documentation (commercial invoice, packing list, certificate of origin) is provided with every shipment. Express courier options (DHL, FedEx, UPS) deliver to most destinations within 3–7 business days. Sea freight consolidation is available for bulk orders. All units ship with a 12-month warranty covering manufacturing defects and functional failure under normal operating conditions.

For regulated-industry procurement (aerospace, nuclear auxiliary systems, pharmaceutical manufacturing), batch traceability documentation and incoming inspection reports are available upon request. Export classification: standard industrial automation component; buyers are responsible for import compliance in their destination jurisdiction.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
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Location: Xiamen, China
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