VT-SR7-1X/0/A4VS.125HS

The VT-SR7-1X/0/A4VS.125HS is an electronic driver module produced by Bosch Rexroth Indramat for the VT-SWMA Modules series. The board conditions a differential command signal and delivers controlled current to a compatible proportional directional or pressure valve. This function supports precise hydraulic actuation in automated machinery and process-control systems. Dither circuitry and auxiliary sensor power are incorporated into the compact board for installation in space-limited control cabinets.

The power section operates from ±24 VDC, while internal monitoring requires the supply to remain within an acceptable range of ±22 VDC to ±28 VDC before the output stage is enabled. Under standby conditions, the board draws <150 mA, helping limit heat generation inside sealed enclosures. A fixed dither generator excites the valve coils at 340 Hz to reduce static friction and promote smooth spool movement. The externally supplied auxiliary rail accepts ±14.8 VDC to ±15.2 VDC and provides the nominal ±15 V supply used by connected sensors. The module does not contain an internal voltage regulator for this auxiliary rail, so the external source must provide the required regulation.

The current loop can source or sink up to ±60 mA during operation, providing bidirectional control for compatible proportional valve coils. Command Value 1 has an input resistance of 50 kΩ, which limits loading on a connected PLC or analog reference source. This high input resistance also helps preserve the accuracy of command signals when several control inputs share a common reference. A +24 V call-up signal energizes the relay, and its winding has a resistance of 700 Ω to limit current through the control circuit. The relay separates the low-power command path from the valve-driving section, while the dither signal reduces hysteresis as the valve moves through its operating stroke. Feedback potentiometers or LVDTs can receive power from the auxiliary rail without requiring a separate regulator on the module.