THORLABS BSC001 User manual

a dvanced p ositioning t echnology
STEPPER MOTOR CONTROLLER
Model Number BSC001
BSC002

THORLABS
About the Company
Thorlabs is a broad based optical technologies company with expertise in the design and
manufacture of an extensive array of innovative photonics products. The product range
covers optical and opto-mechanical components, tables and vibration control,
nanopositioning solutions, test and measurement systems, and laser sources.
Founded in 1989 Thorlabs has become a well known supplier for quality photonics
products for manufacturing and research with an annually published catalog present in
almost every optics laboratory worldwide. Thorlabs has set standards for fastest possible
delivery of its products combined with an excellent customer service. Overnight delivery
of most products, and quick and competent technical support, are widely acknowledged
by its customers.
Besides this main mission Thorlabs is eager to enhance its product spectrum
continuously. Together with specialized strategic partners, like Nova Phase and Menlo
Systems GmbH, Thorlabs investigates the newest optical technologies to provide new
and innovative solutions to its customers.
Thorlabs Inc. has its headquarters in Newton, New Jersey. Subsidiaries are located in
Tokyo (Japan), Karlsfeld (Germany), Ely (UK) und Gothenburg (Sweden).
Trademarks
Windows is a trademark of Microsoft
Corporation.
ActiveX is a trademark of Microsoft
Corporation.
Visual Basic is a trademark of Microsoft
Corporation.
LabVIEW is a trademark of National
Instruments Corporation.
THORLABS is a registered trademark of
Thorlabs Inc.
Revision History
Issue No. Date Summary
1 170703 Initial Issue
2 150903 CN3278
3 090104 CN3296
4231204 CN3451

Contents
1 Introduction ............................................................................................... 3
How to Use this Handbook .............................................................................................3
Handbook Structure .......................................................................................................3
Declarations Of Conformity ............................................................................................4
For Customers in Europe .......................................................................................4
For Customers In The USA ....................................................................................4
2 For Your Safety .......................................................................................... 5
Safety Information ..........................................................................................................5
3 Overview ..................................................................................................... 7
Description .....................................................................................................................7
Software .........................................................................................................................7
Background ............................................................................................................7
APT Server (ActiveX Controls) ..............................................................................8
APT User.exe .......................................................................................................10
APT Config Utility .................................................................................................11
Front Panel Controls and Indicators ............................................................................12
Rear Panel Connections ..............................................................................................13
4 Principle of Operation .............................................................................. 15
How A Stepper Motor Works ........................................................................................15
General Principle .................................................................................................15
Positive and Negative Moves ...............................................................................16
Velocity Profiles ...................................................................................................16
Positioning the Stage ...................................................................................................17
General ................................................................................................................17
Home position ......................................................................................................17
Limit Switches ......................................................................................................18
Minimum and Maximum Positions .......................................................................18
Power Saving .......................................................................................................19
Error Correction ............................................................................................................20
Backlash correction ..............................................................................................20
Continued...

2
5 Set Up And Operation .............................................................................21
Introduction .................................................................................................................. 21
Software Installation and Upgrade ............................................................................... 22
Software Installation ............................................................................................ 22
Software Upgrades .............................................................................................. 22
System Setup ............................................................................................................... 23
Assigning a Serial Number ........................................................................................... 23
Manual Operation ......................................................................................................... 24
Operation from the GUI Panel ............................................................................. 24
Settings Panel ..................................................................................................... 26
6 Installation And Maintenance .................................................................. 31
Mechanical Installation ................................................................................................. 31
Siting .................................................................................................................... 31
Environmental Conditions .................................................................................... 31
Identifying Unsafe Equipment .............................................................................. 31
Electrical Installation .................................................................................................... 32
Connecting To The Supply .................................................................................. 32
Bonding ............................................................................................................... 32
Fuses ................................................................................................................... 32
Electrical Connections ......................................................................................... 33
Rear Panel Motor Control Connector ..................................................................34
Rear Panel User I/O Connector ........................................................................... 35
Rear Panel Drive Channel Connectors ............................................................... 37
Preventive Maintenance ............................................................................................... 38
Safety Testing ...................................................................................................... 38
Cleaning .............................................................................................................. 38
7 Specifications and Associated Products ...............................................39
Specifications ............................................................................................................... 39
Associated Products .................................................................................................... 39

3
Chapter 1
Introduction
1.1 How to Use this Handbook
This handbook contains all the information necessary to set up, program and operate
the BSC series Stepper Motor Controller. For the continuing safety of the operators
of this equipment, and the protection of the equipment itself, read the Safety
Information in Chapter 2 before using theequipment, and carefully heed all cautionary
notes. If you have any questions or comments about this handbook please call your
local sales or service office or contact the factory at [phone] and ask for
Customer Service.
1.2 Handbook Structure
Chapter 1, Introduction, gives an overview of the handbook structure and draws
attention to the importance of the safety information. Chapter 2, For Your Safety,
provides critical information needed for the safe installation and operation of the
equipment. Chapter 3, Overview, gives a explanation of the philosophy behind the
APT system; it also details the rear panel connections and explains the front panel
controls and their use. Chapter 4, Principle of Operation, explains how to use the
module to control external devices. Chapter 5, Setup and Operation¸ describes the
GUI panel controls, and explains the various setting parameters. Chapter 6,
Installation, provides electrical installation instructions together with general
information and guidelines on mounting and siting the equipment. Finally, Chapter 7,
lists the specifications and associated products.

4
Introduction
1.3 Declarations Of Conformity
1.3.1 For Customers in Europe
This equipment has been tested and found to comply with the EC Directives
89/336/EEC ‘EMC Directive’ and 73/23/EEC ‘Low Voltage Directive’ as amended by
93/68/EEC.
Compliance was demonstrated by conformance to the following specifications which
have been listed in the Official Journal of the European Communities:
Safety EN61010: 2001 Installation Category II, Polution Degree II.
EMC EN61326: 1997
1.3.2 For Customers In The USA
This equipment has been tested and found to comply with the limits for a Class A
digital device, persuant to part 15 of the FCC rules. These limits are designed to
provide reasonable protection against harmful interference when the equipment is
operated in a commercial environment. This equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the
instruction manual, may cause harmful interference to radio communications.
Operation of this equipment in a residential area is likelyto cause harmful interference
in which case the user will be required to correct the interference at his own expense.
Changes or modifications not expressly approved by Thorlabs Ltd could void the
user’s authority to operate the equipment.

5
Chapter 2
For Your Safety
2.1 Safety Information
For the continuing safety of the operators of this equipment, and the protection of the
equipment itself,the operator should take note of the Warnings, Cautions and Notes
throughout this handbook and, where visible, on the product itself.
The following safety symbols may be used on the equipment:
Warning, risk of danger. Refer to the handbook for details on this hazard.
Warning, risk of electric shock. High voltages present
Equipotentiality (bonding) terminal
Functional (EMC) earth/ground terminal.
!

6
For Your Safety
The following safety symbols may be used throughout the handbook:
Warning. An instruction which draws attention to the risk of injury or death.
Caution. An instruction which draws attention to the risks of damage to the product,
process or surroundings.
Note. Clarification of an instruction or additional information.
Warnings
• The unit must be connected only to an earthed fused supply of 100 to 240V.
• The Equipment, as described herein, is designed for use by personnel properly trained in
the use and handling of mains powered electrical equipment. Only personnel trained in
the servicing and maintenance of this equipment should remove its covers or attempt any
repairs or adjustments.
• If this equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired. Do not operate the instrument outside its
rated supply voltages or environmental range. In particular, excessive moisture may
impair safety.
• This unit is intended for operation from a normal, single phase supply, in the temperature
range 5° to 40°C, 20% to 80% RH.

7
Chapter 3
Overview
3.1 Description
The BSC001 single channel and BSC002 dual channel APT Stepper Motor
Controllers use the latest high speed digital signal processing (DSP) technology to
provide high resolution microstepping (25,600 steps per revolution). They allow the
user to control up to 2 axes of motion, and additional axes can be driven by
connecting two or more units together via a standard USB hub.
Operator interaction is via an intuitive software interface and all connections are via
the rear panel, which improves cable management and reduces the risk of
entanglement or snagging.
3.2 Software
3.2.1 Background
A common requirement in many optoelectronic alignment and characterization
applications concerns the implementation of automated positioning sequences.
Typically, such positioning sequences require a series of descrete movements and
measurements to implement an overall solution
The mechanical stage options and drive electronics offered by Thorlabs are ideally
suited to performing all of these individual steps in a variety of different ways.
The key to the APT range of controllers (and associated mechanical products)
concerns the ease and speed with which complete automated alignment systems can
be engineered at the software level. All controllers in the APT range are equipped with
USB connectivity. The 'multi-drop' USB bus allows multiple APT units to be connected
to a single controller PC using simple USB hubs and cables.
The USB connection flexibility offered by the APT controllers is matched by the
associated product software. All APT controllers are shipped with a sophisticated
multithreaded ActiveX based software control suite. This suite comprises the main
ActiveX based APT Server with a number of utilities including APTUser and
APTConfig. APT Server is the main software 'engine' that runs on the host PC to
provide all necessary APT services such as generation of sophisticated graphical
instrument panels, multiple unit USB communications and multithreaded execution to
enhance system operation andprevent GUI deadlock. Rather than a single monolithic
entity, the APT Server is actually an interoperating collection of ActiveX Controls (or
simply Controls) together with associated support files and libraries. These ActiveX
Controls, developed using leading edge object oriented coding techniques, are the
key to the powerful, flexible and yet extremely easy to use APT control software.

8
Getting Started
3.2.2 APT Server (ActiveX Controls)
ActiveX Controls are re-usable compiled software components that supply both a
graphical user interface and a programmable interface. Many such Controls are
available for Windows applications development, providing a large range of re-usable
functionality. For example, there are Controls available that can be used to
manipulate image files, connect to the internet or simply provide user interface
components such as buttons and list boxes.
With the APT system, ActiveX Controls are deployed to allow direct control over (and
also reflect the status of ) the range of electronic controller units. Software
applications that use ActiveX Controls are often referred to as 'client applications'.
Based on ActiveX interfacing technology, an ActiveX Control is a language
independent software component. Consequently ActiveX Controls can be
incorporated into a wide range of software development environments for use by
client application developers. Development environments supported include Visual
Basic, Labview, Visual C++, C++ Builder, HPVEE, Matlab, VB.NET, C#.NET
and, via
VBA, Microsoft Office applications such as Excel and Word.
Consider the ActiveX Control supplied for the APT stepper controller unit.
This Control provides a complete user graphical instrument panel to allow the motor
unit to be manually operated, as well as a complete set of software functions (often
called methods) to allow all parameters to be set and motor operations to be
automated by a client application. The instrument panel reflects the current operating
state of the controller unit to which it is associated (e.g. such as motor position).
Updates to the panel take place automatically when a user (client) application is
making software calls into the same Control. For example, if a client application
instructs the associated stepper motor Control to move a motor, the progress of that
move is reflected automatically by changing position readouts on the graphical
interface, without the need for further programming intervention.
The APT ActiveX Controls collection provides a rich set of graphical user panels and
programmable interfaces allowing users and client application developers to interact
seamlessly with the APT hardware. Each of the APT controller modules has an
associated ActiveX Control and these are described fully in system online help or the
handbooks associated with the controllers. In addition to the main ActiveX Server, a
number of other utilities are supplied with the APT system, most notably APTUser and
APTConfig. Note that these utilities themselves take advantage of and are built on top

9
BSC Series Stepper Motor Controller
of the powerful functionality provided by the APT ActiveX Server (as illustrated in the
system architecture diagram below).

10
Getting Started
3.2.3 APT User.exe
The APTUser application allows the user to interact with a number of APT hardware
control units connected to the host PC. This program displays multiple graphical
instrument panels to allow multiple APT units to be controlled simultaneously.
All basic operating parameters can be altered and, similarly, all operations (such as
motor moves) can be initiated. For many users, the APTUser application provides all
of the functionality necessary to operate the APT hardware without the need to
developany further custom software. For those who do need to further customise and
automate usage of the APT modules (e.g. to implement an alignment algorithm), this
application illustrates clearly how the rich functionality provided by the APT ActiveX
Controls are used by a client application. The complete Visual Basic source project is
provided as a useful aid to software developers.

11
BSC Series Stepper Motor Controller
3.2.4 APT Config Utility
There are many system parameters and configuration settings associated with the
operation of the APT Server (ActiveX Controls). Most can be directly accessed using
the variousgraphical panels and their associated programmable interfaces. However
there are several system wide settings that can be made 'off-line' before running the
APT software.These settings haveglobal effect; suchas switching betweensimulator
and real operating mode, associating mechanical stages to specific motor actuators
and incorporation of calibration data.
The APTConfig utility is provided as a convenient means for making these system
wide settings and adjustments. Full details on using APTConfig are provided in the
online help supplied with the utility.

12
Getting Started
3.3 Front Panel Controls and Indicators
Fig. 3.1 Front panel controls and indicators (dual channel version)
Power LED – Indicates that power is applied to the unit.
Channel 1 and Channel 2 buttons – Used to enable/disable channel functionality.
The associated LED is lit when the channel is enabled. Disabling the channel allows
the motor actuator to be operated manually.

13
BSC Series Stepper Motor Controller
3.4 Rear Panel Connections
Fig. 3.2 Rear panel connections (dual channel version)
DRIVE CHANNEL 1 -Provides connection to the actuator associated with channel 1.
DRIVE CHANNEL 2 - (Dual Channel Versions Only) Provides connection to the
actuator associated with channel 2.
These two connectors provide all phase current drive and encoder feedback
connections to drive a range of encoded and non-encoded stepper motors - see
Section 6.2.7.
USER I/O - The User I/O connector exposes a number of internal electrical signals.
For convenience, a number of logic inputs and outputs areincluded, thereby negating
the needfor extraPC based IOhardware. Usingthe APT support software,these user
programmable logic lines can be deployed in applications requireing control of
external devices such a relays, light sources and other auxillairy equipment. - see
Section 6.2.6. for further details.
MOTOR I/O - The ‘Motor I/O’ connector exposes a number of electrical signals useful
for external control. Interlock enable lines are used to enable/disable the motor drive
outputs and are a useful mechanism for implementing an external emergency stop
feature. Motor jogging lines can be used to jog the motor in both forward and reverse
directions. Jogging parameters (e.g. jog distance) are set via the GUI panel.
Note. If a remote handset is not used, the terminator supplied must be fitted.
COMMS - USB port for system communications.
Bonding point - Used to electrically bond multiple units to eliminate circulating earth
(ground) currents. Do not connect to the main power supply ground.
TRIG. IN and Trig. Out - For future development use.
CONTROL I/O
TRIG. IN
DRIVE CHANNEL 2DRIVE CHANNEL 1
TRIG. OUT
USER I/O
MOTOR CONTROL
USB
bonding point
POWER
90 - 264 VAC, 47 - 63 Hz, 250 VA
FUSES F1 and F2: T 3A, ANTISURGE CERAMIC
!

14
Intentionally Blank

15
Chapter 4
Principle of Operation
4.1 How A Stepper Motor Works
4.1.1 General Principle
The actuators driven by the BSC series controllers use a stepper motor to drive a
precision lead screw.
Stepper motors operate using the principle of magnetic attraction and repulsion to
convert digital pulses into mechanical shaft rotation. The amount of rotation achieved
is directly proportional to the number of input pulses generated and the speed is
proportional to the frequency of these pulses. A basic stepper motor has a permanent
magnet and/or an iron rotor, together with a stator. The torque required to rotate the
stepper motor is generated by switching (commutating) the current in the stator coils
as illustrated in Fig. 4.1.
Fig. 4.1 Simplified concept of stepper motor operation
Although only 4 stator poles are shown above, in reality there are numerous tooth-like
poles on both the rotor and stator. The result is that positional increments (steps) of
1.8 degrees can be achieved by switching the coils. If the current through one coil is
increased as it isdecreased inanother, the newrotor position is somewhere between
the two coils and the step size is a defined fraction of a full step (microstep).
The size of the microstep depends on the resolution of the driver electronics. When
used with the Thorlabs APT motor controller, the smallest angular adjustment is 0.014
degrees,resultingin a resolution of25,600 microsteps per revolution. The mechanical
resolution achieved by the system may be coarser than a single microstep, primarily
becausethere may bea small difference between the orientation of the magnetic field
generated by the stator and the orientation in which the rotor comes to rest.
N
S
on
on
N
S
on
on

16
Principle of Operation
4.1.2 Positive and Negative Moves
Positive and negative are used to describe the direction of a move. A positive move
means a move from a smaller absolute position to a larger one, a negative move
means the opposite.
In the case of a linear actuator, a positive move takes the platform of the stage further
away from the motor.
In a rotational stage, a positive move turns the platform clockwise when viewed from
above.
4.1.3 Velocity Profiles
To prevent the motor from stalling, it must be ramped up gradually to its maximum
velocity. Certain limits to velocity and acceleration result from the torque and speed
limits of the motor, and the inertia and friction of the parts it drives.
The motion employed is described by a trapezoidal velocity profile, reflecting the
shape of the velocity vs. time graph (see Fig. 4.2.), thereby driving the stage to its
destination as quickly as possible, without causing it to stall or lose steps.
The stage is ramped at acceleration ‘a’ to a maximum velocity ‘v’. As the destination
is approached, the stage is decelerated at ‘a’ so that the final position is approached
slowly in a controlled manner.
Fig. 4.2 Graph of a trapezoidal velocity profile
velocity
maximum
velocity (v)
time
acceleration (slope) a

17
BSC Series Stepper Motor Controller
4.2 Positioning the Stage
4.2.1 General
Whenever a command to move a stage is received, the Control PC converts the
movement specified in motion units, (e.g., mm) to a number of microsteps. It then
sends a signal to the stage to move by this number of microsteps.
Each motor in the system has an associated electronic counter in the Control PC,
which keeps a record of the net number of microsteps moved. If the Control PC is
requested to report the position, the value of this counter is converted back into
motion units.
Note. During a manual move, (i.e. if the motor shaft is turned by hand) no signal is sent
to the motor, the counter is not updated and any subsequent position reporting will be
false until the motor is ‘Homed’.
4.2.2 Home position
When the system is powered up, the counters in the controller are all set to zero and
consequently, the system has no way of knowing the position of the stage in relation
to any physical datum.
A datum can be established by sending all the motors to their ‘Home’ positions. The
‘Home’ position is set during manufacture and is determined by driving the motor until
the negative limit switch is reached and then driving positively a fixed distance (zero
offset).
When at the Home position, and the counters are reset to zero thereby establishing a
fixed datum that can be found even after the system has been switched off.

18
Principle of Operation
4.2.3 Limit Switches
A linear stage moves between two stops, and movement outside these limits is
physically impossible. Linear stages can include stages that control the angle of a
platform within a certain range, although the movement of the platform is not really
linear but angular. Rotary stages can rotate indefinitely, like a wheel.
Linear and rotary stages both contain microswitches that detect certain positions of
the stage, but they differ in the way these switches are used.
All linear stages have a –ve limit switch, to prevent the stage from accidentally being
moved toofar in the –ve direction. Once this switch is activated, movement stops. The
switch also provides a physical datum used to find the Home position. Some linear
stages have a +ve limit switch also, whereas others rely on a physical stop to halt the
motion in the positive direction. A rotary stage has only one switch, used to provide a
datum so that the Home position can be found. Movement is allowed right through the
switch position in either direction.
Fig. 4.3 Stage limit switches
In addition to these hardware (outer) limit switches, the APT server also incorporates
software (inner) limit switches (see Fig. 4.4), which allow a client application to
emulate the inner limit switches through software. This may be useful in some
applications where a particular stage should be prevented from moving to its
hardware limits, e.g. to prevent clashes between mechanical components. See the
SetSWPosLimits method in the on-line help file for more details on software limits.
4.2.4 Minimum and Maximum Positions
These positions are dependent upon the stageto which the motors are fitted, and are
defined as the minimum and maximum useful positions of the stage relative to the
‘Home’ position - see Fig. 4.4.
The distance from the Minimum position to the Maximum position is the ‘useful travel’
of the stage. It is often the case that the Minimum position is zero. The Home and
Minimum positions then coincide, with movement always occurring on the positive
side of the Home position.
Rotary stages have effectively no limits of travel. The Minimum and Maximum
positions are conventionally set to 0 and 360 degrees respectively. When the position
of a rotary stage is requested, the answer will be reported as a number between 0 and
360 degrees, measured in the positive direction from the Home position.
Rotary
stage
Linear stage
Datum switch
–ve limit switch or stop
+ve limit switch