RTC
®
5 PC Interface Board
Rev. 1.9 e
7 Basic Functions for Scan Head and Laser Control
128
7.4 Laser Control
The RTC
®
5 provides several laser control signals
with programmable pulse length and frequency via
the LASERON, LASER1 and LASER2 ports of the 15-pin
D-SUB-laser connector (see page 46) or of the
EXTENSION 2 connector (see page 50). These signals
can be used for controlling various types of lasers.
Via the command set_laser_mode (see page 443),
the user can choose one of seven different laser
control modes:
•The CO
2
mode (laser mode 0) is provided for
controlling CO
2
lasers.
• The four YAG modes (laser modes 1, 2, 3 and 5)
are provided for controlling Nd:YAG and related
lasers.
• Laser mode 4 and laser mode 6 generate a contin-
uously-running control signal.
Depending on the selected mode, different laser
control signals are available for “laser active” oper-
ation and “laser standby” operation. The various laser
modes are described in the following sections.
All laser control signals are TTL signals. They can be
set to either active-high or active-low via the
command set_laser_control (see page 440) – also
see page 46. The command get_startstop_info
(Bit#13) can be used to query whether the signals are
currently set to active-high or active-low.
The maximum current load for all signals is 20 mA.
7.4.1 Enabling, Activating and
Switching Laser Control
Signals
After a hardware reset and also after initialization
with load_program_file, all laser control signals are
disabled. All laser output ports (LASERON, LASER1
and LASER2) are in the (high impedance) tristate
mode. TTL states (LOW or HIGH) will only be available
if the signals are enabled via the set_laser_control
command (and the desired TTL level is thereby spec-
ified).
After set_laser_control is called:
• Laser control signals for “laser active” operation
will be provided at all output ports as soon as
these signals have been activated and switched
on
or
• All output ports will provide standby signals if
they have been activated and if no laser control
signals for “laser active” operation are switched
on
or
• The outputs will be in their basic TTL states (e.g.
LOW if a high signal level was specified) if no laser
control signals (neither for “laser active” nor for
“laser standby” operation) have been activated
After set_laser_control has been called, the laser
output ports (LASERON, LASER1 and LASER2) will
enter the (high impedance) tristate mode only after a
new hardware reset or if the laser control signals are
subsequently disabled via a command (see
disable_laser, pause_list and
set_laser_control(bit#2 = 1)).
Before activation of the laser control signals, the
command set_laser_mode should be called for
selecting the laser control mode (otherwise – by
default – the CO
2
mode is selected).
For first-time activation of the laser control signals
(both for “laser active” and for “laser standby” oper-
ation), the set_laser_control command must be
used to enable the laser output ports (LASERON,
LASER1 and LASER2).
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