20
IA VRD UK.INDD RH 02.06
Digital Power Amplifier
Series VRD350 and VRD355
Installation Manual
Parker Hannifin GmbH & Co. KG
Hydraulic Controls Division
2.4. Diagnosis
Test Sockets
The sockets for I
A
and I
B
can be used to measure
the solenoid currents independently. The volt-
age at the socket is roughly proportional to the
solenoid current. The voltage is around 1V at 1A.
At the socket S6 for the sum total of both analog
command signals (SW5 and SW6), the measured
value appears according to the input signals. At
the socket for the actual value (A), the measured
value is proportional to the actual value signal. The
measured value is analogous to display U11.
Internal Diagnostic Parameters (U-Parame-
ters)
Internally computed values can be displayed on the
7-segment display during normal operation and to
aid commissioning and trouble shooting. Values
should be interpreted as voltage or current with a
resolution standardised in the display at 10mV to
9.99V. The relevant position in the software func-
tions can be taken from the block diagrams. For
U1
Command signals
Display
in V
U2
Value after the ramp generator
U3
Value after the linearisation table
U4
Value after amplifier gain adjustment
U5
Signal to solenoid A
U6
Signal to solenoid B
U7
Solenoid A current
Display
in mA or A
U8
Solenoid B current
U9
Total current solenoid A + solenoid B
The following values are available in the basic
version:
Further outputs are available with the feedback
option card:
U10
Command signal, reference input variable
Display
in V
U11
Feedback value controlled variable
U12
Control difference (error)
U13
Controller output (correcting variable)
Note
Parameter setting and diagnostics only possible
for VRD355 using ABG35S.
Only trained staff should make pa-
rameter changes. The drive should
be switched off whilst adjusting para-
meters.
2.5. Parameters
S-Parameters
Command signals and ramp times are adjusted by
means of S-Parameters. They may be set during
normal operation and the alteration is immediately
effective.
Display
S1...S4
Command signals as voltage
0...9.99V
S5...S8
Ramp times in seconds
(increment 0.01s)
0...9.99s
(increment 0.1s)
10...39.5s
S5
Ramp from 0 to -
(A-Solenoid)
S6
Ramp from - to 0
(A-Solenoid)
S7
Ramp from 0 to +
(B-Solenoid)
S8
Ramp from + to 0
(B-Solenoid)
H-Parameters (auxiliary parameters)
Parameters H1 and H2 are used in the commission-
ing phase or in test and measurement sequences
for simple input of command signals (command
signal simulation). This allows a command signal to
be input independent of external inputs (command
signal 5/ command signal 6 or selection of S1 to
S4 and a direction), without requiring additional
external circuitry.
Parameters can be set during operation. Any al-
teration with
⇑
and
⇓
is immediately effective. The
polarity sign shows which of the two output stages
or solenoids the command signal acts on.
Positive sign
Solenoid B
Negative sign
Solenoid A
All command signals are also additive in the H
mode. This means that when command signals
are input (internally S1 to S4 and externally SW5 to
SW6), these are added to active H-parameters, tak-
ing into account the signs. By switching over from H
1 to H2, or the reverse, it is possible to switch over
to different values - also with opposite sign.
This is only an auxiliary function. Pre-
cise measured values, comparable
with a multimeter, are not possible for
technical reasons.
The enable signal must be present so
that the output stages are active and
current can flow.
