Features:
– Ideal for controlling direct-acting and pilot-operated proportional pressure control valves without electrical position feedback
– Differential Inputs
– Additional command value input, 0 to +9 V
– Ramp generator with separately adjustable rising and falling ramps
– Clock current output stage
– Clock Current Output Stage Reverse Voltage Supply Polarity Protection
– Short circuit protection
Function Description
The command value voltage can be applied to command value input 1 directly or via an external command value potentiometer using the regulated voltage of + 9 V of the power supply unit [8].
For this input the following conditions are valid: + 9 V = + 100 % 1).
Command value input 2 is a differential input [1] (0 to + 10 V). This input must be used if the command value is fed forward from an external electronic device with another reference potential (e.g. from the PLC).
This input must be used. When cutting in or out the command value voltage, take care to connect the two signal lines to or disconnect them from the input.
Prior to transmission, the two command values are dcs-sis.com summed [2] and fed to the potentiometer [3], which is available on the front panel of the card and is used as an attenuator to limit the maximum command value.
The Downstream Ramp Generator [4] generates a ramp-shaped output signal from the step input signal. The time constant of this signal can be adjusted to ramp up and ramp down using two potentiometers.
The specified ramp time is related to the command value step change of 100% and can be about 1 sec. or 5 sec. depending on the jumper setting. If a command value step change of less than 100 % is applied at the input of the ramp generator or when the attenuator [3] is set, the ramp time can be adjusted upwards and downwards.
or when the attenuator [3] is active, the ramp time is shortened accordingly.
With the aid of the external contact “ramp up/down”, the ramp time can be set to a minimum value (approx. 30 ms) for the upper and lower ramp times respectively.
The output signal of the Ramp Generator [4] is an internal current command value and is fed into the measurement socket “w” on the front panel of the card.
In addition, the command value is transferred to the current output stage [6] via the current regulator [5].
The current regulator [5] adds the value of the bias current potentiometer “Zw” (R130) to the value of the ramp generator.
The current command value is modulated by the clock pulse encoder signal [7]. The clocked actual current value acts like a constant current and superimposes a jitter signal in the valve solenoid.
The actual current value through the solenoid valve can be measured at socket “I”. Here, a voltage of 800 mV corresponds to a current of 800 mA.