28
IA VRD UK.INDD RH 02.06
Digital Power Amplifier
Series VRD350 and VRD355
Installation Manual
Parker Hannifin GmbH & Co. KG
Hydraulic Controls Division
Action
Input
Terminal
Signal at Input
E-stop activated
U
Supply
or Enable
32bd
0V
8d
0V
Restart and/or apply enable
signal and set command signals
to 0V.
U
Supply
and/or Enable
32bd
24V
and S1 to S4
8d
24V
8z, 4d, 6d, 6z
S1
∧
S2
∧
S3
∧
S4 = 0V
Set set = actual
Automatically performed by amplifier
Activate the normal mode of
operation; external and internal
command signals are once again
processed.
one from S1 to S4
and
one from + or -
8z, 4d, 6d, 6z
4z, 2z
(S1
∨
S2
∨
S3
∨
S4) = 24V
∧
(+
∨
-) = 24V
Sequence with active Safety Function
Drive to starting position. The starting position corresponds to the active setpoints. The selected internal
command signal (S1
∨
S2
∨
S3
∨
S4), and possibly the external command signal is used.
External Closed Loop
The structure of the closed loop is as in the fig-
ure on page 17. Other types of loop control, e.g.
speed controI for rotational drives, are connected
similarly.
The ramp function is useful in external closed-loop
systems to avoid overdriving the valve and con-
troller. E.g. in position control loops, the ramps
determine the speed of the drive.
Using the equations given on page 22 enables
the computation of parameters from the loop gain
factor. In cases where these calculations are not
applicable, the parameters have to be determined
experimentally.
During commissioning and after an e-stop, unde-
sired drive movements may occur. The drives are
normally run at a specified speed. This is imple-
mented by the internal ramp functions (S5 to S8).
If the e-stop chain is activated, either the supply
voltage or the enable is switched off. If only the
enable is switched off, you must pay attention to
the safety instructions on page 22! After restarting
(supply voltage or enable on), there is usually a
large deviation. This then leads to unwanted move-
ments at the drive. The deviation is the result of the
ramp-controlled command signal start from zero.
A specific software function ensures that uncon-
trolled movements are avoidable. To activate this
safety option, following parameter settings have to
be programmed:
Avoid instability of the control loop dur-
ing the experimentation. This may cause
damage to the drive or machine.
Precondition: E14 = 1... 6 and E2 = 4
This means, if E14 = 1...16, external
control loops are activated.
If E2 = 4 the safety function is switched
on. If E2 = 1 and E2 = 3 it is not active.