User Manual
E727T0005, valid for E-727
BRO, 2019-06-28
Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany Page 118 / 240
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email info@pi.ws, www.pi.ws
How to work with the DDL
NOTICE
Damage to the stage and the load from oscillations!
Using DDL could be critical if there are any residual oscillations in the system; DDL will then cause
the oscillations to build up—the more wave generator cycles are used for DDL initialization, the
stronger the effect.
Before you work with Dynamic Digital Linearization (DDL), eliminate any residual oscillations
by adjusting the notch filter(s) and the servo-control parameters (P-term, I-term; see "Servo-
Controller Dynamic Tuning" (p. 134)).
INFORMATION
The Dynamic Digital Linearization (DDL) feature must be expressly ordered (order# E-710.SCN).
You can activate it after purchase and without opening the device. See "How to activate the DDL
License" (p.
117) for more information.
If you are not sure if the DDL feature is activated on your controller, use the SPA? command to
check the value of parameter 0x0E000401 (DDL License Valid). If the parameter value is 1, the
DDL feature is activated, otherwise it is deactivated.
DDL related commands will not provoke an error when the DDL feature is deactivated.
The number of DDL tables can be queried using the TLT? command. The number of DDL tables
present in the E-727 is the same as the number of logical axes, and each DDL table is dedicated to
one axis.
A certain amount of memory space is reserved for the DDL data (ask with the SPA? command,
parameter ID 0x1400000B). 256144 memory points are available. The individual DDL tables may
use different portions of the complete memory space—the number of points in a DDL table
corresponds to the length of the waveform which was output during the DDL initialization. You can
ask for the current DDL table length using the DTL? command.
DDL tables are automatically filled with data when a wave generator is started with the "Use and
reinitialize DDL" option activated. It is also possible to write data "manually" with the DDL
command—in this case, make sure that the DDL table length is correct (see DDL command
description for more information).
INFORMATION
The DDL initialization must be repeated when a new stage is connected, the servo parameters are
changed (e.g. due to load changes) or the waveform is changed.
It is recommended to start the DDL initialization for all axes at the same time. Each new
initialization will stop all running initialization processes. The initialization process is also stopped
by the DDL command.
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