W.E.S.T. Elektronik POS-124-A-PDP, Техническая документация инструкция

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W . E . ST .
Elektronik GmbH
Page 22 of 45 POS-124-*-PDP-1121 13.02.2013
5.2.7 VMODE1 / VMODE2 (Switching over the control mode)
Command Parameters Unit Group
VMODE1 X
VMODE2 X
x= SDD|NC
EXP
The fundamental control structure can be changed with this parameter.
SDD: S troke- D ependent D eceleration. In this mode, stroke-dependent deceleration is activated. This
mode is the default mode and is suitable for most applications. With stroke-dependent decel-
eration the drive comes to a controlled stop at the target position. From the set deceleration
point the drive then switches to control mode and moves accurately to the desired position.
This control structure is very robust and reacts insensitively to external influences such as fluc-
tuating pressures.
One disadvantage is that the speed varies with the fluctuating pressure as the system runs
under open-loop control.
NC: N umerically C ontrolled. In this mode a position profile is generated internally. The system al-
ways works under control and uses the following error to follow the position profile. The magni-
tude of the following error is determined by the dynamics and the set control gain. The ad-
vantage is that the speed is constant (regardless of external influences
2
) due to the profile
demand. Because of continuous control, it is necessary not to run at 100% speed, as other-
wise the errors cannot be corrected. 80% of the maximum speed is typical although especially
the system behaviour and the load pressure should be taken into account when specifying the
speed.
5.2.8 VMAX1 / VMAX2 (Maximum speed in NC Mode)
Command Parameters Unit Group
VMAX1 X
VMAX2 X
x= 1… 5000 mm/s VMODE = NC
Specification of the maximum speed in NC Mode. This value is defined by the drive system and should be
specified as precisely as possible (not too high under any circumstances)
3
. The maximum speed is
scaled by means of the VELO value or via the external speed demand. The command is only active if the
VMODE has been parametrised to NC.
2
There are deviations due to external influences which are then compensated for. The time response is defined by
the system dynamics.
3
If the retraction speed and the outward speed are different, the smaller one has to be used