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PQ-132-U
3.3 Method of operation
3.3.1 General
Enable:
This digital input signal initializes the application and error messages are deleted. The
READY
signal
gets activated. The output signal to the control element is enabled. The drive can be controlled by the Q value
or input.
Setting
RUN
will start the PID controller. The command signal input and the feedback signal inputs are evalu-
ated now. Input
PIN5
provides additional functions depending on the parameter
PIN:5
. Either a switching be-
tween the two parameter sets is possible or the ramp function can be activated and deactivated with this input.
3.3.2 p/Q-pressure-control
This module serves to control pressures and forces on hydraulic actuators. The control structure is performed
as a classical p/Q scheme (flow control with pressure limit control). A short cycle time provides an adequate
reserve in dynamic requirements of the regulation.
Alternatively, it can be used with a pressure sensor or a force cell. Two pressure signal inputs can be used for
the differential pressure control. The two setpoints (Q and p) provided as analogue variables, one for the vol-
ume current setpoint (trial of the cylinder) and one as the pressure setpoint. A ramp generator is connected in
series with the pressure setpoint.
The output signal is available as a differential output for connection of control valves with integrated electron-
ics.
3.3.3 Functionality
For p/Q control a dynamic zero-overlapped control valve is necessary. If the B-side of the cylinder cannot be
relieved, pressure in both cylinder sides has to be measured.
The cylinder can be driven in both directions with the analogue Q command input value (± 10 V) and limits the
max velocity. The pressure limitation control function is only active with a positive Q signal.
The p-command value pre-sets the max differential pressure. If this pressure (or force) is exceeded, the con-
troller reduces the output signal to the valve (also in the negative range), so that the preset pressure will be
kept. To go backwards for keeping the force is possible.
The pressure/force is determined via the analogue inputs X1 and X2. For differential pressure control the ac-
tual value is calculated (X1
– X2).
