Scanlab RTC 4 Owner's manual

Installation and
Operation
The RTC®4 PC Interface Board
for Real Time Control of Scan Heads and Lasers
July 7, 2006RTC®4 PC Interface Board
Rev. 1.3 e
innovators for industry

SCANLAB AG
Siemensstr. 2a
82178 Puchheim
Germany
Tel. [phone]
Fax: [phone]
[email protected]
www.scanlab.de
©SCANLAB AG 2006
(Doc. Rev. 1.3 e - July 7, 2006)
SCANLAB reserves the right to change the information in this document without notice.
No part of this manual may be processed, reproduced or distributed in any form (photocopy, print, microfilm or by any other
means), electronic or mechanical, for any purpose without the written permission of SCANLAB.
All mentioned trademarks are hereby acknowledged as properties of their respective owners.

RTC®4 PC Interface Board
Rev. 1.3 e
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Contents
1 Delivered Product .............................................................................................................................. 6
1.1 Package Contents ...................................................................................................................... 6
1.2 Manufacturer ............................................................................................................................ 6
1.3 About This Operating Manual ................................................................................................... 6
2 Product Overview ............................................................................................................................... 7
2.1 Intended Use ............................................................................................................................. 7
2.2 System Requirements ................................................................................................................ 7
2.3 Board Dimensions And Layout ................................................................................................... 8
2.4 Notes For RTC®3 Users ............................................................................................................ 10
Hardware Changes .......................................................................................................... 10
Installation Tips ............................................................................................................... 10
Changes in the Command Set ......................................................................................... 10
3 Safety During Installation And Operation ....................................................................................... 11
3.1 Steps For Safe Operation ......................................................................................................... 11
3.2 Laser Safety ............................................................................................................................. 11
4 Principle Of Operation ..................................................................................................................... 12
4.1 Software Concept .................................................................................................................... 12
List Commands And Control Commands ......................................................................... 12
List Handling ................................................................................................................... 13
Automatic List Handling .................................................................................................. 13
External Control Inputs .................................................................................................... 13
Synchronization Of Processing ........................................................................................ 14
4.2 Scan Head And Laser Control .................................................................................................. 15
Vector Commands ........................................................................................................... 15
Arc Commands ................................................................................................................ 15
Microsteps ....................................................................................................................... 15
4.3 Delays ...................................................................................................................................... 16
Laser Delays ..................................................................................................................... 16
Scanner Delays ................................................................................................................ 17
Notes On Optimizing The Delays ..................................................................................... 24
4.4 Image Field Size ....................................................................................................................... 29
4.5 Image Field Correction ............................................................................................................ 30
4.6 Laser Control ........................................................................................................................... 32
CO2Mode ....................................................................................................................... 33
YAG Modes ..................................................................................................................... 34
Softstart Mode ................................................................................................................ 35
Laser Mode 4 .................................................................................................................. 37
4.7 Status Monitoring and Diagnostics ......................................................................................... 38
4.8 intelliSCAN®- Additional Functions .......................................................................................... 38
The XY2-100 Enhanced Protocol ..................................................................................... 38
Selecting Data Signals ..................................................................................................... 38
Querying Data ................................................................................................................. 39

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5 Advanced Programming .................................................................................................................. 40
5.1 Coordinate Transformations .................................................................................................... 40
5.2 Wobbel Function ..................................................................................................................... 41
5.3 Using Two Different Correction Files ........................................................................................ 42
Double Scan Head Configuration .................................................................................... 42
Using Two Correction Files In A Single Scan Head System ............................................... 42
5.4 Using Multiple RTC®4 Boards In One Computer ...................................................................... 43
5.5 Circular Queue Mode ............................................................................................................... 44
5.6 Structured Programming ......................................................................................................... 45
Input Pointer ................................................................................................................... 45
List Jumps ....................................................................................................................... 45
Conditional List Jumps .................................................................................................... 45
Output Pointer ................................................................................................................ 45
Programming Examples ................................................................................................... 46
5.7 Scanning Raster Images (Bitmaps) ........................................................................................... 47
5.8 Timed Jump And Mark Commands .......................................................................................... 50
5.9 Automatic Self-Calibration ....................................................................................................... 51
6 Electrical Connections ...................................................................................................................... 52
6.1 Laser Connector ....................................................................................................................... 52
Analog Output ports ....................................................................................................... 52
Laser Signals .................................................................................................................... 52
External Control Signals .................................................................................................. 52
6.2 Laser Extension Connector ....................................................................................................... 53
8-Bit Digital Output Port ................................................................................................. 53
Laser Signals .................................................................................................................... 53
6.3 Primary Scan Head Connector ................................................................................................. 54
Control Signals ................................................................................................................ 54
Status Signals .................................................................................................................. 54
6.4 Secondary Scan Head Connector (Optional) ............................................................................ 54
6.5 Data Cable ............................................................................................................................... 55
6.6 Optical Data Interface (Optional) ............................................................................................. 56
6.7 EXTENSION 1 Connector .......................................................................................................... 56
16-Bit Digital Input and Output ...................................................................................... 56
BUSY Status ..................................................................................................................... 56
7 Options ............................................................................................................................................ 57
8 Installation And Start-Up ................................................................................................................. 58
8.1 Jumper Settings Overview ....................................................................................................... 58
8.2 Changing The Jumper Settings ................................................................................................ 59
TTL Laser Signal Level ...................................................................................................... 59
Laser / Analog Output Ports (9-Pin Laser Connector) ....................................................... 59
Digital Output Port (Laser Extension Connector) ............................................................. 60
8.3 Installing the Hardware ........................................................................................................... 60
8.4 Installing the Drivers ................................................................................................................ 61
8.5 Start-Up and Functionality Test ................................................................................................ 61

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9 Software ........................................................................................................................................... 62
9.1 Installing the Software ............................................................................................................ 62
9.2 DLL Calling Convention ............................................................................................................ 62
Pascal .............................................................................................................................. 62
Basic ................................................................................................................................ 62
C ..................................................................................................................................... 63
9.3 Initializing the RTC®4 .............................................................................................................. 63
9.4 Demo Programs ....................................................................................................................... 64
10 Commands And Functions ............................................................................................................... 69
10.1 Overview ................................................................................................................................. 69
Control Commands ......................................................................................................... 70
List Commands ................................................................................................................ 71
10.2 Data Types ............................................................................................................................... 72
10.3 Command Set .......................................................................................................................... 73
10.4 Supported and Unsupported RTC®2 Commands ................................................................... 125
11 Troubleshooting ............................................................................................................................. 128
12 Customer Service ........................................................................................................................... 129
12.1 Servicing and Repairs ............................................................................................................. 129
12.2 Warranty ............................................................................................................................... 129
12.3 Contacting SCANLAB ............................................................................................................. 129
12.4 Product Disposal .................................................................................................................... 129
13 Technical Specifications ................................................................................................................. 130

RTC®4 PC Interface Board
Rev. 1.3 e
1 Delivered Product
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1 Delivered Product
1.1 Package Contents
The contents of the package are listed in detail in the
“Package Description” file.
Check the package for damage and confirm that
all parts have been delivered. If anything is
missing, please contact SCANLAB.
Keep the packaging, including the antistatic bag
the RTC®4 board is delivered in, so that in case of
repair the board can be properly repackaged and
returned to SCANLAB.
1.2 Manufacturer
SCANLAB AG
Siemensstr. 2a
82178 Puchheim
Germany
Tel. [phone]
Fax: [phone]
[email protected]
www.scanlab.de
1.3 About This Operating Manual
This operating manual is a part of the product. Please
read these instructions carefully before you proceed
with installation and operation of the RTC®4. If there
are any questions regarding the contents of this
manual, please contact SCANLAB (see previous
section).
Keep the manual available for servicing, repairs and
disposal. This manual should accompany the product
if ownership changes hands.
This manual refers to the following versions of the
RTC®4 software and firmware:
• DLL: RTC4DLL.DLL , version 400 or higher,
• DSP program files:
RTC4D2.HEX / RTC4D3.HEX ,
version 2.400 / 3.400 or higher,
•RTC
®4 firmware: version 128 or higher.
The following commands return the current software
and firmware version numbers:
•get_dll_version (page 82);
•get_hex_version (page 83) and
•get_rtc_version (page 84)
Supplements To This Manual
The following RTC®4 supplementary manuals are
available from SCANLAB:
•"3D Software" manual
•"Processing-On-The-Fly Software" manual
•"I/O Extension Board" manual
•"correXion and CFMP" manual

RTC®4 PC Interface Board
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2 Product Overview
2.1 Intended Use
The RTC®4 PC Interface Board from SCANLAB is
designed for real-time control of scan heads and
lasers via an IBM-compatible PC with a PCI bus
interface.
The RTC®4 is based on a fast digital signal processor
(DSP) system providing full real-time control for
a wide range of applications, including enhanced
double scan head control and runtime image
transformations.
The included software driver provides an extensive
set of control commands. The RTC®4 stores and
processes these commands completely indepen-
dently of the host PC. This makes it possible to meet
the stringent demands of real-time scan head and
laser control even if the PC must simultaneously
respond to other tasks such as machine control and
network communication.
The RTC®4 offers various laser control signals for all
commonly used laser types. The user can select from
four different laser control modes. In addition, the
output signals can be customized to meet special
requirements.
The standard version of the RTC®4 includes a 16-bit
digital input port, a 16-bit digital output port, an
8-bit digital output port and two general purpose
analog output ports with 10-bit resolution.
The following options are available from SCANLAB:
• control signals for simultaneous control of two
scan heads, with individual image field correction
(on-board) for each scan head
• control signals for Processing-on-the-fly
applications (on-board)
• control signals for a third axis, e.g. a varioSCAN
(on-board)
• I/O Extension Board
• Optical Data Interface
Only hardware extensions from SCANLAB should be
used in combination with the RTC®4.
2.2 System Requirements
Hardware
The RTC®4 requires an IBM-compatible personal
computer with a PCI bus interface and at least one
free PCI slot. The dimensions of the RTC®4 board are
shown in figure 1 on page 8.
A second PCI slot is required if the optional I/O
Extension Board is to be used.
SCANLAB offers additional PCI slot covers with D-SUB
connectors for the following options:
• second scan head
• Processing-on-the-fly
• laser extension connector with
8-bit digital output port
Software
Software drivers for the Microsoft operating systems
WINDOWS XP and WINDOWS 2000 are included in
the package. They support the RTC®4's plug and play
facility and simultaneously drive up to eight RTC®4
boards.
The RTC®4 software package also includes discon-
tinued software drivers for the Microsoft operating
systems WINDOWS XP SP1 / 2000 / NT 4 and
WINDOWS ME / 98 / 95. However, please note this
driver and DLL version is no longer supported by
SCANLAB. Functionality upgrades will be imple-
mented in the new driver version only.

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2.3 Board Dimensions And Layout
1
Legend
VB2 . . . . . . . . . . . . . . . . . . Primary scan head connector (D-SUB 25-pin female)
VB3 . . . . . . . . . . . . . . . . . . Laser connector and analog output ports (D-SUB 9-pin female)
MARKING ON THE FLY . . . . Connector for Processing-on-the-fly applications (optional) –
please refer to the supplement manual "Processing-On-The-Fly Software"
2. SCANHEAD . . . . . . . . . . Secondary scan head connector (optional)
EXTENSION 1. . . . . . . . . . . Connector with a 16-bit digital input and a 16-bit digital output
(optional: connector for the RTC®4 I/O Extension Board)
EXTENSION 2. . . . . . . . . . . Connectors for the RTC®4 I/O Extension Board (optional) –
please refer to the supplement manual "I/O Extension Board"
LASER EXTENSION . . . . . . . Additional laser connector with 8-bit digital output port
X6/X7/X3 . . . . . . . . . . . . . Jumper bank for laser connector VB3
X10 . . . . . . . . . . . . . . . . . . Jumper for setting the laser signal level
X8/X9 . . . . . . . . . . . . . . . . Jumper bank for the LASER EXTENSION connector
SN . . . . . . . . . . . . . . . . . . . Serial number
All connectors are described in section 6 on page 52.
The jumper settings are described in detail in section 8.1 on page 58.
VB3
VB2
X6 X7 X3
X10
X8 X9
SN
102 mm
160 mm
PCI CONNECTOR
MARKING ON THE FLY
2. SCANHEAD
EXTENSION 1 EXTENSION 2
LASER EXTENSION
Layout of the RTC®4 standard version

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Optionally, the RTC®4 PC interface board can be
delivered with an optical data interface.
2
Legend
U213/U211 . . . . . . . . . . . . Primary scan head connector (ST connectors)
U212/U214 . . . . . . . . . . . . Secondary scan head connector (ST connectors, optional)
VB3 . . . . . . . . . . . . . . . . . . Laser connector and analog output ports (D-SUB 9-pin female)
MARKING ON THE FLY . . . . Connector for Processing-on-the-fly applications (optional) –
please refer to the supplement manual "Processing-On-The-Fly Software"
EXTENSION 1. . . . . . . . . . . Connector with a 16-bit digital input and a 16-bit digital output
(optional: connector for the RTC®4 I/O Extension Board)
EXTENSION 2. . . . . . . . . . . Connectors for the RTC®4 I/O Extension Board (optional) –
please refer to the supplement manual "I/O Extension Board"
LASER EXTENSION . . . . . . . Additional laser connector with 8-bit digital output port
X6/X7/X3 . . . . . . . . . . . . . Jumper bank for laser connector VB3
X10 . . . . . . . . . . . . . . . . . . Jumper for setting the laser signal level
X8/X9 . . . . . . . . . . . . . . . . Jumper bank for the LASER EXTENSION connector
SN . . . . . . . . . . . . . . . . . . . Serial number
All connectors are described in section 6 on page 52.
The jumper settings are described in detail in section 8.1 on page 58.
VB3
U212
U214
U213
U211
X6 X7 X3
X10
X8 X9
MARKING ON THE FLY EXTENSION 1 EXTENSION 2
LASER EXTENSION
SN
102 mm
160 mm
P I ONNE TOR
Layout of the RTC®4 with optical data interface

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2.4 Notes For RTC®3 Users
This section summarizes how the RTC®4’s hardware
and software differ from that of the RTC®3 PC
Interface Board and provides the RTC®3 user with tips
on installing an RTC®4.
Hardware Changes
•StandardRTC
®4 boards are equipped with an
EXTENSION 1 connector. This connector provides
a 16-bit digital input and a 16-bit digital output
(previously only available via an optional RTC®3
I/O Board) as well as access to the BUSY status
signal (see "EXTENSION 1 Connector", page 56).
•TheRTC
®4 PC Interface Board is optionally
available with an optical data interface (see
"Optical Data Interface (Optional)", page 56). This
eliminates the need for an add-on board to
implement optical data transmission between the
PC interface board and the scan system's
(optional) integrated optical data interface.
Installation Tips
•RTC
®4 and RTC®3 boards in the same
computer cannot be operated simultaneously.
•RTC
®4 and RTC®3 boards use the same Windows
driver. Nevertheless, even if an RTC®3 board has
already been installed in a computer, the setup
program must still be called again. On the other
hand, after an RTC®4 is installed, an RTC®3 board
can be operated without newly installing the
driver.
Also follow the guidance in "Installation And Start-
Up", page 58.
Changes in the Command Set
New Commands
• The new Arc Commands (see page 15) support
marking with basic arcs.
• Commands for Status Monitoring and
Diagnostics (see page 38) are suitable for both
monitoring the operational status and
diagnosing the scan system.
• The 16-bit digital input and 16-bit digital output
at the EXTENSION 1 connector can be queried or
set via I/O commands (see "16-Bit Digital Input
and Output", page 56). Some of these I/O
commands can execute conditional jumps
dependent on the current value of the digital
input, thereby expanding support for structured
programming (see "Conditional List Jumps", page
45). These commands were previously only
available with the optional RTC®3 I/O Board.
Changed Commands
The RTC®3 command rtc3_count_cards contains the
designation “rtc3”. The RTC®4 version of the
command is called rtc4_count_cards (see page 101).
Unsupported Commands
A group of RTC®2 commands still usable on the
RTC®3 are not supported by the RTC®4. However,
these unsupported commands can be replaced by
equivalent RTC®4 commands.
The section Supported and Unsupported RTC®2
Commands (see page 125) lists all emulated RTC®2
software commands, unsupported RTC®2 commands
and RTC®4 equivalents.

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3 Safety During Installation And Operation
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3 Safety During Installation And Operation
Please read these operating instructions completely
before you proceed with installing and operating the
RTC®4 PC Interface Board.
If there are any questions regarding the contents of
this manual, please contact SCANLAB.
The following symbols are used in this manual:
3.1 Steps For Safe Operation
3.2 Laser Safety
The RTC®4 is intended for controlling a laser scan
system. Therefore all relevant laser safety directives
must be known and applied before installation and
operation. The customer is solely responsible for
ensuring the laser safety of the entire system.
Instructions that may affect a person’s
health are marked with a warning
triangle next to the word "Danger".
Instructions that recommend appro-
priate use of this device or warn of
damage that may occur to it are
labeled by a circle with an "X" through
it, next to the word "Caution".
Caution!
• Carefully check your application program before
running it. Programming errors can cause a
break down of the system. In this case neither
the laser nor the scan head can be controlled.
• Protect the board from humidity, dust, corrosive
vapors and mechanical stress.
• For storage and operation, avoid electro-
magnetic fields and static electricity. These can
damage the electronics on the RTC®4 board. For
storage, always use the antistatic bag the RTC®4
is delivered in.
• The allowed operating temperature range is
25 °C ± 10 °C.
• The storage temperature should be
between – 20 °C and +60 °C.
!Danger!
• All applicable laser safety directives must be
adhered to. Safety regulations may differ from
country to country. It is the responsibility of the
customer to comply with all local regulations.
• Please observe all laser safety instructions as
described in your scan head or scan module
manual, chapter 3 "Safety during Installation
and Operation".
• Always turn on the PC and the power supply
for the scan head first before turning on the
laser. Otherwise there is the danger of
uncontrolled deflection of the laser beam.
SCANLAB recommends the use of a shutter
to prevent uncontrolled emission of laser
radiation.
!

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4 Principle Of Operation
4.1 Software Concept
Figure 3 shows a simple laser marking sample(1).
The image is made up of straight line segments or
vectors. The RTC®4 software driver provides a set of
jump commands and mark commands for drawing
such vector images. Each of these commands
describes one vector. The RTC®4 software driver
provides arc commands for producing circular arcs.
Additional software commands are available for
controlling the laser during the marking process.
The RTC®4 processes the commands it receives and
precisely transmits the required marking signals to
the scan head using a pre-defined 10 µs time raster
and to the laser. The scan head’s galvanometer
scanners accurately position their deflection mirrors
in synchronization with the incoming control signals.
The control signals are transferred to the galva-
nometer scanners digitally in accordance with the
industry standard XY2-100 (or for optical data
transfer in accordance with the XY2-100-O protocol).
Current scan head status information can be queried
via the RTC®4, also in accordance with the XY2-100
(or XY2-100-O) protocol.
The RTC®4 provides various analog and digital signal
outputs freely available for tailoring laser control to
customer-specific requirements. The customer
assumes responsibility for use of these signals.
List Commands And
Control Commands
The RTC®4 command set consists of
control commands and list commands.
Control commands are executed immediately.
They are used for controlling execution of lists and for
setting some general parameters. Other control
commands are provided for direct laser and scan
head control.
Before a list command can be sent to the RTC®4, a
list must be opened via a control command. List
commands sent to the RTC®4 afterwards are not
executed immediately, but stored in a list buffer. Only
after the list is closed and started, the RTC®4 reads
the commands from the list buffer and processes
them in real time. The RTC®4 provides two list
buffers. Each list buffer can hold one list ("list 1" or
"list 2") with up to 4000 list commands. If an
application needs only one list, then the RTC®4’s
entire memory can be treated like a single list with a
capacity for 8000 commands. In this case, list 1 can
be loaded with up to 8000 commands (but list 2
must not be used). This also makes possible the use
of structured programming.
List commands include jump commands,
mark commands and arc commands, as well as
commands for setting various scanning parameters
such as laser power, jump speed and marking speed.
Some commands exist in two versions: as a list
command and as a control command. Among these
dual-version commands are the I/O commands.
All RTC®4 commands are described in detail
in chapter 10 "Commands And Functions".
An overview is provided in chapter 10.1, page 69.
(1) In this manual, laser marking is mentioned only as an example
of the many possible laser materials processing applications.
3
A laser marking sample
Jump
Mark
Mark
Mark
Mark
Mark
Mark
Mark Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Mark
Jump
Jump
Jump
Jump
Jump
Jump
Mark

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List Handling
The command set_start_list (see page 116) opens a
list buffer for writing. After finishing the data input,
the list must be closed with the command
set_end_of_list.
As soon as a list is closed, it can be started either with
the command execute_list (see page 81) or by an
external start signal (see the section "External Control
Inputs", right).
During the execution of one list, the other list buffer
can be loaded with the next list. The host computer
and the RTC®4 then work in parallel. The second list
can only be started after execution of the first list has
finished. During execution of a list, execute_list
commands and external start signals are ignored.
Execution of a list can be stopped at any time, e.g. for
implementing an emergency shutdown or for any
other purpose. Use of the stop_execution command
(see page 119) or an external stop signal will imme-
diately abort the currently running list and turn off all
RTC®4 laser signals.
To examine the current status of the lists, the
commands get_status (page 86) or read_status
(page 100) can be used.
Automatic List Handling
Continuous Transfer
The commands auto_change and auto_change_pos
(see page 75) activate an automatic list change. That
causes the next sequence of commands to start auto-
matically when the current list is finished. In this
manner, continuous data transfer to the scan head
can be achieved without non-productive pauses.
The command auto_change can be called when
working with two lists (each with a maximum
capacity of 4000 commands). This command should
only be called while a list is executing or after a list
has finished. Additionally, the next list should have
already been loaded and closed (by a call of the
command set_end_of_list).
The auto_change_pos command can be called when
the RTC®4’s entire memory is to be treated like a
single list. The start position (address in list memory)
of the next command sequence is specified by the
command.
Repeating Output
Alternatively, continuous data transfer can be
achieved by alternately repeating output of the two
lists:
Load and close the two lists.
Start one of the lists with the command
execute_list.
While the first list is running, call the command
start_loop (see page 119). This causes a
continuous, automatic and alternately repeating
output of both lists from the RTC®4 to the scan
head, until you choose to call the command
quit_loop, which will terminate the continuous
output as soon as the current list is finished.
Circular Queue
A completely different mode of operation for
continuous data transfer is described in chapter 5.5
"Circular Queue Mode", page 44.
External Control Inputs
To also enable start and stop execution of a list via
external signals, the RTC®4 provides two external
control inputs, /START and /STOP
(TTL active-low). These control inputs are accessible
via the 9-pin D-SUB laser connector VB3 on the RTC®4
board – see figure 23 on page 52. Both signal inputs
are internally connected to +5 V via pull-up resistors
(10 kΩ).
Both inputs are active-LOW, i.e. the corresponding
pin must be set to the LOW level (0 V) to start or to
stop execution.
STOP Signal
If the /STOP input is at the LOW level for at least
10 µs, execution of the currently running list is
aborted immediately and the RTC®4 laser signals are
turned off. This is equivalent to calling the command
stop_execution (see page 119).
The /STOP input is always enabled. It can, for
instance, be used to implement an emergency
shutdown.

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START Signal
Before the /START input can be used, it has to be
enabled with the command set_control_mode (see
page 103). Subsequent START requests will start the
loaded list. The list will only be started by the external
START request if it is closed and no list is executing at
the moment.
The desired list can be selected via the command
select_list (page 102).
Alternatively, the list command set_extstartpos_list
(see page 105) can be used.
To check whether a list was successfully started,
the command get_startstop_info (see page 85)
can be used.
Notes
• An explicit call of the command stop_execution
disables the external /START input. An external
/STOP signal also (at least temporarily) disables
the external /start input, i.e. as long as the /STOP
input is LOW. The command set_control_mode
(see page 103) defines whether or not the /START
input also stays disabled when the /STOP signal is
no longer active.
• Please note that the /START input is edge sensitive
(HIGH to LOW level transition), whereas the /STOP
input is level sensitive.
Synchronization Of Processing
The command set_wait (see page 118) makes it
possible to set wait markers (break points) within a
list. Each marker is associated with a number greater
than zero.
When the RTC®4 reaches a wait marker, processing of
the list is temporarily interrupted and the laser is
turned off.
The command get_wait_status (see page 88) ascer-
tains whether processing is currently interrupted at a
marker. If processing is interrupted, the command
get_wait_status returns the number (wait_word) of
the corresponding marker. Otherwise the command
returns zero.
The wait markers are provided for synchronization
purposes. The application program should perform a
handling routine for each wait marker.
When that handling routine is finished, processing of
the list can be resumed via the control command
release_wait (see page 101).

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4.2 Scan Head And Laser Control
Vector Commands
The basic commands for scan head control are the
jump commands and the mark commands. These
commands require as parameters the X and Y coordi-
nates of the end point of the corresponding vector(1).
Each vector starts at the current output position,
which is usually the end point of the preceding
vector. The initial output position at start-up
(or after a reset of the RTC®4) is the center of
the image field, i.e. the point (0|0).
Please refer to chapter 4.4 "Image Field Size", page 29
for a description of the image field coordinate
system.
Jump Commands
A jump command (jump_abs or jump_rel) causes a
(usually) fast movement of the scanner mirrors. The
laser focus "jumps" to the new position. In general,
the laser is switched off during the jump. The jump
speed can be defined with the list command
set_jump_speed (see page 107).
If the laser system does not allow fast switching, the
jump speed must be set high enough to prevent a
visible marking effect on the workpiece. Also see the
command home_position (page 89).
Mark Commands
The RTC®4 automatically turns on the laser at the
beginning of a mark command. During a mark
command (mark_abs or mark_rel), the laser focus
moves along the specified vector with a constant
marking speed, producing a straight mark on the
workpiece.
If another mark (or arc) command follows immedi-
ately afterward, the RTC®4 leaves the laser on.
Therefore, a sequence of individual mark (and arc)
commands creates a polyline mark. The laser is
turned off after the last mark (or arc) command in a
series of mark (or arc) commands, or if the end of the
current list is reached.
The list command set_mark_speed (see page 109)
defines the marking speed. The marking speed
can be changed anywhere in a list.
Arc Commands
The RTC®4 software driver provides arc commands
for marking circular arcs. These commands require
parameters for the X and Y coordinates of the arc
center and the arc angle. The arc starts at the current
output position.
At the beginning of an arc command, the RTC®4 also
automatically turns on the laser. During an arc
command (arc_abs or arc_rel), the laser focus moves
with the defined marking speed along the specified
arc. The laser is turned off after the last arc (or mark)
command in a series of arc (or mark) commands, or
if the end of the current list is reached.
Microsteps
Each vector defined by a jump, mark or arc command
is divided into a number of small steps by the RTC®4.
These microsteps are transferred to the scan head at
a constant time rate (output period ∆t) In controlling
its galvanometer scanners, the scan head implements
the steps via an analog servo loop.
Figure 4 shows how the X component of a vector is
divided into microsteps. The Y component is split up
in the same way.
(1) The coordinates must be specified as digital control values
(without units). To avoid confusion with coordinates in [mm],
SCANLAB uses the expression “coordinate values [in Bits]”.
x
Dt
Dx
(t
0
| x
0
)
(t
1
| x
1
)
(t
0
+i·Dt | x
0
+i·Dx)
x
0
x coordinate of the current output
position before scanning the vector
x
1
x coordinate of the end position
of the vector
Dt step period
Time
4
The X component of a vector is split up into microsteps.

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The length ∆s of each microstep is
∆s=v·∆t,
where vis the current jump speed (marking speed).
The output period ∆t of the position update is usually
fixed at 10 µs. It is the same for 2D and for 3D appli-
cations. The output period cannot be set by the user.
The 16-bit data output width of the RTC®4 allows up to 216
microsteps per vector or arc. If the marking speed is quite
low and the vector or arc is very long, a step period of 10 µs
would possibly lead to more than 216 microsteps. In this
case, the RTC®4automatically increases the output period to
20 µs (or to a suitable multiple of 10 µs, if necessary).
Marking Time
The marking time consumed by any particular
marking process can be measured by calling the
command save_and_restart_timer (see page 101)
before and after the marking process. This command
saves the current value of the RTC®4’s integrated
timer and resets the timer value to 0. The measured
time can be read via the command get_time (see
page 86), which returns the timer value saved during
the most recent call of save_and_restart_timer.
4.3 Delays
The timing of the scan head and laser control signals
must be compatible with the dynamic behavior of the
scan system, i.e. the response of the scanners and the
laser, and the specific interaction between the work-
piece and laser radiation.
To accomplish this, the user can set the following
delays:
•LaserOndelay
• Laser Off delay
• Jump delay (optional variable)
•Markdelay
• Polygon delay (optional variable)
All delays are described in detail in this chapter.
Laser Delays
The LaserOn delay and the LaserOff delay are set by
the list command set_laser_delays (see page 107).
The time resolution for the laser delays is 1µs.
The delays must be appropriate for the defined jump
speed and marking speed (also see "Notes On Opti-
mizing The Delays", page 24).
• There are two different laser delays:
LaserOn delay and LaserOff delay.
• The laser delays affect when the laser is turned
on or off before or after a mark or arc command
or a series of mark and arc commands. Laser
delays do not affect the total marking time,
except when they are negative.

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LaserOn Delay
The LaserOn delay defines the moment when the
RTC®4 turns on the laser. LaserOn delay is automati-
cally inserted at the start of a mark or arc command
(first microstep). Thus, the laser is switched on only
after execution of the first few microsteps. This delay
can be used for several purposes:
• Many applications require laser marking without
variations of intensity, especially without burn-in
effects at the start or end of a vector. To achieve
homogenous marking results, it is essential to
scan the vectors with a constant velocity.
At the beginning of a mark or arc vector, however,
the mirrors first have to be accelerated up to the
defined marking speed. Figure 7 on page 19
shows that the laser focus initially moves only
very slowly. A burn-in effect may occur.
To avoid this, the LaserOn delay must be set to a
suitable, positive value. Thus the mirrors will have
already reached a certain angular velocity when
the laser eventually turns on. However, if the
LaserOn delay is too long, the first part of
the vector will be cut off.
• Some materials take some time until they react to
the exposure to laser radiation. In this case, it can
be useful to "preheat" the starting point of a mark
or arc vector before marking. This can be done by
setting the LaserOn delay to a negative value.
A negative LaserOn delay extends the total marking
time, because it is inserted before the actual mark or arc
command.
LaserOff Delay
• Due to the acceleration phase at the beginning
of the movement, a difference (lag) occurs
between the set position and the real position
of each mirror – see figure 7 on page 19.
After execution of a mark or arc command, the
laser should not be turned off immediately
because the scanners have not yet reached the
final set position. Therefore a LaserOff delay is
inserted automatically before the laser is turned
off.
Scanner Delays
The command set_scanner_delays (see page 113)
defines the scanner delays. The time resolution for
the scanner delays is 10 µs.
Jump Delay
When executing a jump command, the mirrors first
have to be accelerated up to the defined jump speed.
Because of the inertia of the mirrors, a lag occurs
between the set position and the real position –
see figure 5 on page 18.
At the end of the jump, a certain settling time is
necessary for the mirrors to reach the set position
within some accuracy. To allow for the settling time
and for the lag, the RTC®4 inserts a jump delay after
each jump command, before the next command is
executed.
Note that the necessary settling time depends on the
selected jump speed. A higher jump speed usually
requires a longer jump delay. The total time needed
for the entire jump command is the sum of the actual
jump time and the jump delay. It can be minimized by
optimizing the jump speed and the jump delay.
• There are three different types of scanner delays:
jump delay, mark delay and polygon delay.
After each vector or arc command, the RTC®4
inserts one of these delays before the next
command is started.

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Variable Jump Delay
During a jump vector, the laser focus (output
position) usually moves with a constant linear
velocity, the jump speed. Since the jump speed is the
same for each jump vector, a constant jump delay is
required for settling of the mirrors.
However, if a jump vector is very short, the scanners
might not reach the full jump speed during the jump
because of the inertia of the mirrors. In this case, a
shorter jump delay might be sufficient for settling.
To make use of this, the RTC®4 offers a variable jump
delay mode. In this mode, the jump delay for short
jump vectors will be reduced in time, as shown in
figure 6 on page 18. The minimum jump delay (for a
jump vector of zero length) and the jump length limit
are set by the user with the command
set_delay_mode (see page 104).
When using the variable jump delay mode, total
marking time can be reduced, especially in
applications involving many short jumps.
Notes
To t u rn off the variable jump delay mode, simply
set the parameter
JumpLengthLimit to zero.
Time
Real
Position
Lag
Jump
Delay
Jump
Command
Set Position
(Microvectors)
LaserPosition
5
Scan head control timing during a jump command with a jump
delay. The laser is not turned on.
0
l
Jump
6
Minimum Jump Delay,
set by set_delay_mode
Variable Jump Delay
Top: length lof the jump vector
Bottom: Variation of the jump delay
Constant Jump Delay,
set by set_scanner_delays
Jump Length Limit,
set by set_delay_mode
Jump Length l
Jump Delay

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Mark Delay
Although the marking speed is usually lower than
the jump speed, a lag between the set position and
the real position occurs not only during a jump, but
also during a mark or arc command.
To make sure that the scanners reach the final
set position properly before the next command
starts, the RTC®4 inserts a mark delay after a single
mark or arc command or after the last mark or arc
command of a polyline – also see figure 7 on
page 19.
Notes
• If a mark or arc command is followed by a zero
jump, mark or arc command, then the MarkDelay
is not executed.
• If a jump vector is followed by a zero jump vector,
then the first JumpDelay is not executed.
In contrast, the JumpDelay is executed if the jump
vector is followed by a zero mark or arc
command.
…
Time
LaserPosition
Set Position
LaserOn
Delay
LaserOff
Delay
Mark
Command
Mark
Delay
Real Position
Lag
7
Scan head and laser control timing during a mark or arc command
with a mark delay. Grey shaded areas indicate that the laser is on.

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Polygon Delay
Between two successive mark or arc commands,
there is no need for a complete stop of the scanners.
Therefore the mark delay between two successive
mark or arc commands is replaced by a polygon delay
– see figure 8 on page 20.
The mark delay and the polygon delay can be set
independently . In addition, the RTC®4 is able to vary
the length of the polygon delay, depending on the
angle between two marking vectors or the tangents
of the arcs. See the section "Variable Polygon Delay"
on page 21 for details.
…
Time
Laser
LaserOn
Delay
LaserOff
Delay
Polygon
Delay
Mark
Command
Mark
Command
Last Mark
Command
In This Polyline
Mark
Delay
Polygon
Delay
Jump
Command
etc.
Position
Set Position
Real Position
8
Scan head and laser control timing during a polyline with a constant polygon delay