About this product 15/52
RE 30214-B/03.2019, VT-MRMA1-1,
Bosch Rexroth AG
5.2.3 Functions within the amplifier module
Pressure command value preparation takes places at various levels:
• Analog pressure command value provision with adjustable zero point correction
(current or voltage interface)
• Ramp generator for pressure increase or pressure reduction of the pressure
command value
• Pressure command value attenuator
• Linearization for compensating for the non-linear valve characteristic curve through
generation of the relevant valve position command value
• Amplitude limitation of the valve position command value
The result of command value preparation is the internal pressure command value
and the internal valve position command value.
Table 6: Pressure command value feedforward
Purpose
Effect
Setting
The pressure command value
feedforward generates the
internal pressure command
value signal from an external
pressure command value
signal taking account of zero
point compensation (zero
point potentiometer).
Pressure increase/reduction as
the pressure command value
becomes higher/lower.
Configure input with DIL
switch
S1
to “0 to 10 V
differential input” or “4 to
20 mA current input“. Zero
point potentiometer
Z
W
: 30 %
When using the differential input (pressure command value) always activate or
deactivate both inputs simultaneously.
Make sure that the ground of the pressure command value (-w
P
, terminal 5) has
the same potential as the ground (L0, terminal 11) of the power supply unit (if
required, use an equipotential bonding strip to suppress disturbance more
effectively).
For carrying out zero point compensation using zero point potentiometer ZW,
potentiometer G
W
must not be turned to the left-hand limit stop (= 0 %).
If the current input is not connected or in the event of a command value cable
break, the resulting internal pressure command value signal is < 0 %. In any case,
the valve comes to a standstill at its current position. When the enable is not set,
the valve cannot be adjusted, positioning control is inactive, but the positioning
signal (”command value reached”) and the pressure switch are active. The pressure
command value has therefore also to be applied when the enable signal is missing.
Table 7: Ramp generator
Purpose
Effect
Setting
Limits the increase in the
pressure command value input
signal.
A given step-change signal is
turned into a ramp-shaped
output signal.
Separate potentiometers
t<
and
t>
for the ramp times of
pressure increase or pressure
reduction. The ramp time
refers to a signal change of
100 %.
The ramp time is not extended or reduced by the downstream ”pressure
command value attenuator”.
Command value
preparation (1)
Pressure command value
feedforward (2)
Ramp generator (3)
