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Elektronik GmbH
Page 11 of 45
POS-124-*-PDP-1121
13.02.2013
Positioning sequence:
The positioning is controlled via Profibus. After releasing (
ENABLE
input), the command
position is set to the actual position of the sensor and the axis stays in closed loop position control
mode. The
READY
output indicates that the system is generally ready for operation. When setting the
START-signal
, the preset command value will be taken over. The axis immediately will drive to this new
command position and indicates reaching it by setting the
InPos
output.
The
InPos
output stays active as long as the axis is within the preset
InPos
window and the
START
input
is active. The driving velocity is forced by preset parameter, too.
The axis can be driven in manual mode (
START
is off) using the control bits
HAND
+ or
HAND
-. The
velocity is programmable. When the
HAND signal is
deactivated, the command position is set to the actu-
al position and the system stays in closed loop position control mode.
Setting the synchronous bit (GL) will synchronize both axes and the synchronization controller is overrid-
ing the position controller of axis 2. Axis 2 is now following axis 1 according to the master-slave-principle.
Influences on positioning accuracy:
The positioning accuracy is determined by the hydraulic and mechanical conditions. The right choice of
valve is therefore a decisive factor. In addition, two mutually contradictory requirements (short position
time and high accuracy) must be taken into account when designing the system.
The electronic limitations lie mainly in the resolution of the analogue signals, although with our modules a
resolution of < 0.01% only needs to be considered with long positions. In addition, the linearity of the indi-
vidual signal points (PLC, sensor and control module) must be considered. The worst-case scenario is
that a system-specific absolute fault occurs.
The repeat accuracy is, however, not affected by this.
V+
V+
A:A
D:A
A:B
D:B
MAX:A
MAX:B
driving out
volumetric flow
P-A
and B-T
control direction
control direction
driving in
