RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
201
innovators for industry
8.11.4 Calibration During an Applica-
tion
Automatic Self-Calibration
Automatic self-calibration of the scan system during
an application can be executed with
Command
= 1). Here, a measurement
routine is started for determining the current Home-
In positions. From the resulting deviation compared
to the previously (with
Command
= 0) stored reference
value, the RTC
®
5 calculates and sets gain and offset
values – separately for the X and Y axis. This resulting
drift compensation setting has immediate effect on
the current output positions and all subsequent ones.
It remains in effect until
Command
= 1) is
called again or until drift compensation is shut off
with
Command
= 2)
(whereby the settings
Gain = 1.0 and Offset = 0 take effect).
Notes
Command
= 0, 1 and
2), the galvanometer scanners will be in the same
position as before the command. However, a
newly calculated or set drift compensation might
lead to correction of the position.
• After a reset or initialization (via
), automatic drift compen-
sation is switched off – as with
Command
= 2). Nevertheless, previously determined
reference values remain available.
• The calibration routine started with
(
Command
= 1) typically lasts 1-2 seconds
(depending on the magnitude of the drift). But if
(
Command
= 1) isn’t preceded by
(
Command
= 0 or 4), then an automatic
ASC hardware check will be performed, which
can extend the command’s execution time by a
few seconds.
Customer-Specific Calibration
Automatic self-calibration is midpoint centered, so
that the image field’s center remains stable. If an
alternative is preferred (e.g. if the left edge should
remain stable, size is irrelevant), then the calibration
can also be externally calculated and set. For such a
customer-specific calibration, the
command can be used to query the Home-In position
that was detected and stored in the DLL with
Command
= 0, 1 or 3). The drift can be deter-
mined via repeated calls of the commands
Command
. From this,
compensating gain and offset factors can be calcu-
lated and then set via
. The resulting drift
compensation setting has effect immediately on the
current output position and all subsequent ones.
Notes
•
returns the current (last determined)
Home-In positions. Directly after
(
Command
= 0), these are also the last
determined and stored Home-In reference values.
Directly after initialization (
returns the reference values from the
EEPROM (also see
command
description).
• After
, a correction of the current position
might occur at jump speed.
• Gain and offset correction factors can also be set
via
for systems
without
Home-In sensors.
• After
(
Command
= 3), the galvanometer
scanners will be in exactly the same position as
before the command.
