The VT-VSPD-1-2X/V0/0-0-1 is a digital valve amplifier manufactured by Rexroth for proportional valves without electrical position feedback. Here’s how:
Core component: The core component of the amplifier is a microcontroller, which is responsible for controlling the entire process. Configuration data, control values, and parameters are stored in non-volatile flash memory.
Parameter setting and interface: Valve selection, configuration and parameter setting can be done through PC program BODAC. It has a serial interface and a local bus, through which up to 32 amplifiers can be connected, and a bus address is assigned to each valve amplifier via BODAC. In models with a display, configuration, parameter setting, and diagnosis can be performed directly on the display without the need for a PC.

Control value input: There are a variety of control value input methods, including control value input for voltage or current. The analog input AI4 (b14/b16) is used for ±10V control value presets, and the analog input AI6 (b22/b24) is used for any control value presets from 4 to 20mA. The control value can also be enabled by digital control value and/or preset by analog input, and the control value input can be changed by software in the level signal.
Ramp generation vs. external signal influence: In addition to the internal ramp generation option, AI2 (b6/b8) and AI5 (b18/b20) analog inputs can be used to influence the “rise” and “fall” of a slope with external signals with the correct amount and correct signal.
Special features: For valves that choose to cover the control spool, the software will configure a step function generator to cover the jump.
Digital input and fault diagnosis: Four binary-coded digital inputs can be used to enable parameter groups in memory, storing up to 16 groups. The control is activated by the H level on the strobe input. When an error occurs, such as a broken cable for the control value input or a strobe input that is inactive, the fault message is output to (d22) via a low signal and visually displayed via the “OK” LED on the panel.

The valve amplifier is set-up as printed circuit board in Europe format 100  mm x  160  mm with daughter board, fitted on both sides.

The central unit of the amplifier is a microcontroller which controls the entire process. Data for configuration, command values and parameters are stored in a FLASH in a non-volatile form.
Four binarily coded digital inputs are used to call up parameter sets (command values) from the memory in which you can store a maximum of 16 sets. A call-up activates the command value for the valve spool position with the related ramp times.
More control inputs have the following functions:
Command value valid:
enable by the parameter set activated by the current call-up (H active)
Enable:
activation of the outputs (acknowledge fault message with low→high edge)
The command value can be preset via digital command value call-ups [5] and/or via analog inputs [1]. The analog input AI4 (b14/b16) is to be used for the command value presetting of ±10  V, the analog input AI6 (b22/b24) for any command value presetting from 4 to 20  mA.
Command values from 0 to +10 V (12… 20 mA) control solenoid B.
Command values from 0 to –10 V (4… 12 mA) control solenoid A.
The digital command value is added to the analog command value with the correct sign, according to the set call-up.