Description
The Bosch Rexroth R901077297 (type code VT-VSPD-1-20/V0/0-0-1 or VT-VSPD-1-24/V0/0-0-1) is a Eurocard-format digital valve amplifier module engineered to control proportional directional valves without electrical position feedback. Utilizing a micro-controlled core, it commands proportional solenoids by converting analog or digital command values into a stabilized, pulse-width modulated (PWM) output current loop.
Commercial Availability & Procurement
| Lifecycle and Logistics | Status & Details |
| Product Condition | New Original (Factory Sealed / New Surplus) or Refurbished (Fully certified via dynamic hydraulic load testing) |
| Warranty | 12-month comprehensive industrial warranty |
| Availability | Available in stock; standard global packaging and dispatch within 24 to 48 hours |
| Pricing Note | Pricing is subject to regional availability and current factory component supply conditions. Contact our hydraulic control desk for a firm, itemized quote. |
Technical Specifications
| Parameter | Specification / Value |
| Type Designation | VT-VSPD-1-2X Series (Digital Eurocard variant) |
| Material Number | R901077297 |
| Operating Voltage (U_B) | 24 VDC nominal (Acceptable envelope: 21 VDC to 30 VDC) |
| Current Consumption (I_{max}) | 1.5 A continuous maximum; standby baseline current: 270 mA |
| Analog Input Ranges | Configurable AI1: \pm10 V (R_e > 100 k\Omega); AI2: \pm10 V (R_e > 10 M\Omega) |
| Digital Inputs | Logic 0: 0 to 5 V; Logic 1: 16 V to U_B |
| Command Value Resolution | 5 mV over the \pm10 V dynamic range |
| Output Stage / Drive Format | Pulse-Width Modulation (PWM) with programmable dither frequency |
| Internal Safety Fuse (I_S) | 4 A time-lag fuse |
| Physical Dimensions | Standard Eurocard format (approx. 21 mm x 188 mm x 262 mm) |
| Net Weight | 0.65 kg (1.43 lbs) |
Field Integration & Calibration Tuning
In precision electro-hydraulic circuits, the VT-VSPD module translates user-defined voltage values into mechanical valve spool displacement.
Card Format and Connection Architecture
The R901077297 is designed as a plug-in Eurocard, typically mounted inside a standard 19-inch subrack or a standalone card holder assembly. All physical interfaces route through a standard 64-pin male connector strip (DIN 41612, Form D).
Critical Field Note: Never insert or extract the Eurocard module while the 24 VDC rack power is actively applied. Doing so creates inductive voltage arcs across the power pins, which can corrupt the internal microcontroller’s flash register tables or destroy the low-tolerance input amplifiers.
Software Parameterization and Adjustments
Unlike obsolete analog amplifier cards that rely on multi-turn trimpots, the VT-VSPD series parameters are configured digitally via a front-panel serial interface or localized software application. Field technicians can configure several critical parameters:
- Ramp Times: Independent configuration of acceleration and deceleration ramps to minimize high-pressure hydraulic shock (water hammer effect) within the piping array.
- Dither Frequency: Tailored adjustment of the high-frequency dither signal superimposed on the solenoid current loop. This keeps the valve spool in a micro-vibrational state, neutralizing mechanical static friction (stick-slip) without shifting the target fluid flow rate.
- Zero Point and Max Current (I_{max}): Custom calibration limits to establish the baseline valve opening point and dead-band elimination thresholds.
Frequently Asked Questions
Q: Why does the amplifier module report a “Solenoid Open Loop” or output fault?
This fault condition indicates that the internal diagnostics have detected a break in the current path to the proportional valve. Check the wiring continuity running from the rack connector pins down to the valve solenoid plug. Measure the solenoid coil resistance with a digital multimeter; an infinite ohm reading confirms an open-circuit failure inside the coil housing, requiring a solenoid swap.
Q: Can this card be used to control a proportional valve that features integrated electronics (OBE)?
No. Proportional valves with integrated electronics (On-Board Electronics) accept direct voltage or current command signals (\pm10 V or 4–20 mA) because they already contain built-in driver stages. The VT-VSPD-1 card is a dedicated power amplifier designed exclusively for external mounting to drive bare, non-OBE proportional solenoids.
Q: How do I back up the internal parameter configuration before performing a module replacement?
Connect a PC to the front serial communications port of the active card and use Bosch Rexroth’s dedicated interface utility tool to execute a project upload. Save the resulting parameter configuration file (.cfg or matching extension format) locally. Once the replacement R901077297 module is seated, download this file to flash the identical ramp, current limits, and dither parameters to the new controller card.
