User Manual

User Manual
WATT PILOT
Motorized Attenuator
US ER MAN UAL
Rev 3 November 2013
www.altechna.com
WATT P ILOT
1 . INTRODUCTION
November 2013
This user manual is designed to help to install and operate Watt Pilot. Before installing and operating Watt Pilot please read installation and operation instructions carefully. Safety instructions must be read carefully. If
there are any questions about contents of this manual please contact
[email protected] Altechna reserves the right to update contents of
this manual without any notification.
Copyright UAB Altechna All Rights Reserved
No part of this manual, including the products and software described
in it, may be reproduced, transmitted, transcribed, stored in a retrieval
system, or translated into any language in any form or by any means, except documentation kept by the purchaser for backup purpose, without
the express written permission of UAB Altechna (hereinafter ALTECHNA).
Product warranty or service will not be extended if:
1. The product is repaired, modified or altered. Unless such repair, modification of alteration is authorized in writing by ALTECHNA; OR
TERUPTION OF BUSINES AND THE LIKE), EVEN IF ALTECHNA HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES ARISING FROM ANY
DEFECT OR ERROR IN THIS MANUAL OR PRODUCT.
1 .1 . Wat t P i lot s h o r t d e s c r i p t i o n
SPECIFICATIONS AND INFORMATION CONTAINED IN THIS MANUAL ARE
FURNISHED FOR INFORMATIONAL USE ONLY, AND ARE SUBJECT TO
CHANGE AT ANY TIME WITHOUT NOTICE, AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY ALTECHNA. ALTECHNA ASSUMES NO
RESPONSIBILITY OR LIABILITY FOR ANY ERRORS OR INACCURACIES THAT
MAY APPEAR IN THIS MANUAL, INCLUDING THE PRODUCTS AND SOFTWARE DESCRIBED IN IT.
1 .2 . G e n e r a l s a f e t y r e q u i r e m e n t s
2. The serial number of the product is defaced or missing.
ALTECHNA PROVIDES THIS MANUAL “AS IS“ WITHOUT WARRANTY OF
ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO THE IMPLIED WARRANTIES OR CONDITIONS OF MERCHANTABILITY
FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL ALTECHNA, ITS DIRECTORS, EMPLOYEES OR AGENTS BE LIABLE FOR ANY INDIRECT, SPECIAL INCIDENTAL, OR COSEQUENTIAL DAMAGES (INCLUDING DAMAGES
FOR LOSS OF PROFITS, LOSS OF BUSINESS, LOSS OF USE OR DATA, IN-
THIS MANUAL IS DIRECTLY CONNECTED TO FIRMWARE VERSION. LATEST
FIRMWARE, SOFTWARE AND MANUAL VERSIONS CAN BE DOWNLOADED FROM www.altechna.com.
Products and corporate names appearing in this manual may or may
not be registered trademarks or copyrights of their respective companies, and are used only for identification or explanation and to the
owner’s benefit, without intent to infringe.
CONTENTS
1 . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.4. Operation modes: “Command” mode.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.1. Watt Pilot short description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.5. Operation modes: “Step-Dir” mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.2. General safety requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.6. “STEP/DIR INTERFACE” connector pin out and specifications. . . . . 13
1.3. Symbols.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.7. “MOTOR” connector pin out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.4. Regulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.8. Supported Stepper Motors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.5. Operating and storage conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.9. Watt Pilot controller connection examples
2. OP ERATION P RINCI PLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Motorized Watt Pilot is a computer controlled laser beam attenuation
device. It attenuates free space laser beam/pulse continuously without
introducing additional energy fluctuations. Watt Pilot is controlled by
computer via USB. Also it has “STEP/DIR INTERFACE” connector for controlling via other devices.
and input circuit diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3. PAC K AG ING CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. W RITIN G SOFT WARE FOR WATT PILOT . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7
3.1. Watt pilot main components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. List of supported operating systems for USB drivers.. . . . . . . . . . . . . . . . 17
3.2. Optics assembling.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.2. Serial port parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4. WATT P ILOT SOFT WARE DESCRI PTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.3. Identifying serial port name. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1. Computer requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.4. Serial commands and protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.2. Software installation.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.5. Software recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3. Program first run. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.6. Serial command usage with National Instruments “LabView”. . . 21
4.4. Watt Pilot “Selector” window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.7. Relation between motor position and laser power. . . . . . . . . . . . . . . . . . 21
4.5. Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. WATT PILOT ATTENUATOR DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . 2 2
4.6. Watt Pilot “Control” window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Standard attenuator dimensions.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.7. Program preferences description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.2. Big aperture attenuator dimensions.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.8. Motor settings description.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.3. Watt Pilot controller dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.9. Firmware update.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8. TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4
5. WATT P ILOT CONTROLLER HARDWARE . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Real laser power does not match shown in software. . . . . . . . . . . . . . . 24
5.1. Controller specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.2. “Upgrade controller firmware now?” message appears. . . . . . . . . . . . . 24
5.2. Controller connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.3. Firmware upgrade was unsuccessful or interrupted. . . . . . . . . . . . . . . . . 25
5.3. Controller internal block diagram.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9. LIST OF TABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 5
Motorized Watt Pilot is designed to operate in conjunction with laser
system. All applicable rules and regulations for safe operation of lasers
must be known and applied while installing and operating Watt Pilot.
The customer is solely responsible for laser safety while using Watt Pilot
as standalone device or integrated into system. The customer must consider protective measures.
While assembling or operating Watt Pilot, do not stare at the direct
or scattered laser light even with safety goggles. All parts of the body
must be kept away from the laser radiation. While adjusting laser beam
through Watt Pilot, laser power must be kept as low as possible. Hazardous laser radiation can increase while optical components or instruments are used in combination with Watt Pilot. Appropriate eye protection must be worn at all times. Electrical safety requirements must be
complied while assembling and operating Watt Pilot.
1 .3 . S y m b o l s
WA RNI NG !
Sections marked with this symbol explain dangerous situations that can
result as personal injury or death. Always read the associated information carefully, before performing indicated procedure.
AT TENTI O N !
Paragraphs preceded by this symbol explain hazards that could damage
the instrument and connected equipment or may cause loss of data.
NOTE
These limits are designed to provide reasonable protection against
harmful interference in a residential installation. This equipment generates, uses, and can create radio frequency energy and, if not installed
and used in accordance with the instructions, may cause harmful interference with radio communications. However, there is no guarantee
that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception,
which can be determined by turning the equipment off and on, the
user is encouraged to try to correct the interference by one or more of
the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
•Connect the equipment into an outlet on a circuit different from
that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.
ALTECHNA is not responsible for any radio television interference
caused by modifications of this equipment or the substitution or attachment of connecting cables and equipment other than those specified
by ALTECHNA. The correction of interference caused by unauthorized
modification, substitution or attachment will be treated as responsibility
of the user.
AT TENTI O N !
Cellular phones or other radio transmitters are not recommended to
be used within the range of three meters of this unit since the electromagnetic field intensity may then exceed the maximum allowed disturbance values according to IEC 61326-1.
1 .5 . Op e r at i n g a n d s to r a g e co n d i t i o n s
For proper Watt Pilot functioning please use assigned controller (found
in the same package). Using unassigned controller might be harmful to
the device.
Environmental conditions that must be hold while storing, servicing
and operating are:
• Storage temperature should be between -25 °C and +60 °C.
• Operating temperature is 25 °C ± 10 °C.
• Watt Pilot must be protected from humidity, dust and corrosive vapors to avoid damaging optical components and electronics.
• Avoid strong static electricity and electromagnetic fields.
This manual also contains “NOTES” and “HINTS” written in this form.
1 .4 . R e g u l at i o n
AT TENTI O N !
The following statement applies to the products covered in this manual,
unless otherwise specified herein. The statement for other products will
appear in the accompanying documentation.
NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6
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2 . O P ERATION P RINCI P LE
4 . WATT P ILOT SOFT WARE DESCRI P TION
The motorized Watt Pilot incorporates 2 high performanceBrewster
type thin film polarizer’s, which reflect s-polarized light while transmitting p-polarized light. Rotating phase retardation of λ/2 wave plate is
placed in the incident polarized laser beam. The intensity ratio of those
two beams may be continuously varied without alteration of other
beam parameters by rotating the waveplate. The intensity of either
exit beam, or their intensity ratio, can be controlled over wide dynamic
Rotating λ/2 waveplate
range. P-polarization should be selected for maximum transmission, or
high purity s-polarization should be reflected when maximum attenuation of the transmitted beam takes place. Proper functioning of Watt
Pilot requires optimal configuration of optical elements regarding to
incident laser beam polarization contrast. Higher incident laser beam
polarization contrast, leads to higher Watt Pilot output polarization
contrast.
Brewster type
thin film polarizers
Incident laser beam
Reflected s-polarized laser beam
Transmitted p--polarized laser beam
4 .1 . Co m p u t e r r e q u i r e m e n t s
• Free USB port. Watt Pilot is compatible with USB 1.1, USB 2.0 and USB 3.0
• Computer administrator rights (only for installation)
• Windows XP sp3 (32-bit)
• Windows Server 2003 sp2 (32-bit)
• Windows Vista sp1 (32/64-bit)
• Windows Server 2008 (32/64-bit)
• Windows 7(32/64-bit)
• Windows 8(32/64-bit)
• Microsoft .Net framework 4.0 redistributable (installs automatically)
5. Select installation directory and click “Next” to begin installation:
4 .2 . S o f t wa r e i n s ta l l at i o n
1. Check for and download latest “Watt Pilot” software installer package from http://www.altechna.com/product_details.php?id=824.
Figure 1. Watt Pilot operating principle. Color differences shows intensity of laser beam. Brighter red means more intensive laser beam.
2. Run downloaded “Watt Pilot-Setup.exe” installation file. In case you
are installing on operating system that does not meet requirements,
only USB drivers will be installed. Click “Yes” to continue.
3 . Pa c k a g i n g co n t e n t s
• Motorized attenuator
• Controller
• USB cable (2m length recomended but no longer than 3m)
• 12V power supply cable (optional)
• Software, installation instructions in USB flash
• Two waveplate retaining rings with tightening key
• Brewster polarizator holder (optional)
3 .1 . WATT P ILOT MAIN COM P ONENTS
tional mode (reflection or transmission mode). Also big aperture attenuator option is available.
Watt Pilot can be fixed to an optical table using posts and clamps or to
the custom system while using M6 or M4 screw on the bottom and M4
screw on the side. Seechapter “WATT PILOT ATTENUATOR DIMENSIONS”
on page 58.
3. Installation window will appear, click “Next” to continue:
3.2. Op t i c s a s s e m b l i n g
Optical components are placed into mechanical holders. Main mechanical components of motorized Watt Pilot are shown in Figure 2.
Waveplate mount is designed to fit 1 inch diameter waveplate mount.
N OT E
Powder free gloves must be worn while mounting optical components.
Avoid touching or scratching optical surfaces.
STEP 1. Place polarizers into mechanical adapter. Polarizers must face
each other with surfaces coated with dielectric coating. Dielectric coating is marked with an arrow, so you have to put the polarizer’s with the
arrows on the sides facing each other. Then fix polarizer’s with the plastic
bolts (use all 3 plastic bolts to fix one polarizer).
Polarizer holder
(Depends from optics)
6. “Watt Pilot” software requires “Microsoft.NET Framework 4 Client
Profile” or higher version to be installed. Setup will offer to download
it, choose “Yes” if you have active internet connection. Choose “No” to
download it from http://www.microsoft.com/en-us/download/details.aspx?id=17113 and install it manually. You should choose “No” if
you wish to install any newer version of framework, or do not have a
working internet connection. This dialog will not appear if framework
is already installed. Download size is 42 Mbytes.
7. Setup will download “Microsoft .NET Framework 4 Client Profile”.
N OT E
Do not tighten up the bolts too much since it can bend the polarizer
and thus distort the laser beam.
STEP 2. Put the wave plate into attenuator between two mounting rings
as shown. Be sure that wave plate is immobilized tightly.
Waveplate mount
Step motor
Figure 2. Watt Pilot main components.
Waveplate mount is attached to micro step motor. Waveplate is fixed
using two mounting rings (seeFigure 3). Waveplate inside the waveplate
holder is rotating around the optical axis of incident laser beam. Step
motor and waveplate mount are shipped together in one piece. Polarizer’s are placed into adapter for polarizer’s. Polarizer’s to the mount are
fixed using 6 plastic bolts (3 for each polarizer). Adapter for polarizer’s
and waveplate mount are fixed while using M4 screw.
4. Click “Next”:
STEP 3. Attenuator consists of two mechanical
parts. User should assemble both mechanical parts together.
STEP 4. Use fixing screw
to tighten both parts together.
NOTE
Adapter for polarizer’s can vary from showed in picture depending from
polarizer’s type (“Brewster” or “Broadband” thin film polarizer) and opera-
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Figure 3. Assembling the Watt Pilot.
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8. After download is finished, “Microsoft .NET Framework 4 Client Profile” will be installed, wait for it to complete. This can take more than 10
minutes on slower machine.
• About
This will show software version and contact information. Please include
software version and controller serial number when contacting manufacturer.
11. “Watt Pilot” software icon will appear on “All Users” desktop and “All
Users” start menu.
4 .5 . C a l i b r at i o n
12. Connect waveplate rotator to Watt Pilot controller.
13. Connect Watt Pilot and PC via USB cable.
14. Plug in Watt Pilot power supply jack and AC adaptor to wall outlet.
15. Windows will detect new hardware. Wait until windows configures
new device.
16. Device installation is now complete, launch “Watt Pilot” program
using “Watt Pilot” icon on desktop.
Figure 5. Watt Pilot “Selector“ window. It is displayed every time program is
started. There are three devices attached to PC in shown screenshot. Double
click listed attenuator to open control window for it.
Columns description:
• Name
It is useful to give meaningful titles for each Watt Pilot, because they will
be easily recognized if more than one is used in the same system. For
example, name can be set to “1st Harmonic WP”, and another attenuator
can be named as “2nd Harmonic WP”. New name is saved into controller internal memory, so it will be visible even if connected to another
computer. Name length is restricted to 20 characters maximum. Watt
Pilot can be renamed from “Watt Pilot control” window “Options->Watt
Pilot Name...” menu option.
In order to correctly change output power, software needs to know at
what angle λ/2 waveplate is. It can be fixed in any angle with respect to
rotator. It is known, that waveplate is positioned at 45 degrees at highest
attenuation point, and 0 degrees at zero attenuation. The purpose of
calibration is to obtain angular offset between λ/2 waveplate and rotator
hardware zero position, when one of these two conditions is met. Calibration window is opened automatically on first use of Watt Pilot, or can
be found in menu “Options->Calibration…” in “Watt Pilot control” window. Make sure that attenuator is correctly aligned before calibrating.
4.3. P r o g r a m f i r s t r u n
9. Setup will finish by installing drivers. Click “Next” to continue:
Launch “Watt Pilot” program using “Watt Pilot” icon on desktop or from
“Start Menu->All Programs->Altechna->Watt Pilot->Watt Pilot”. Watt Pilot “Selector” window will appear. At least one device must be displayed
in the list. If the list is empty, please check USB cable, power connection
and “ON/OFF” switch – it must be in “ON” position. Green LED near power switch must be active if power is OK. Click “File->Search For Devices”
to refresh. For more information about Watt Pilot “Selector” window see
section “
Watt Pilot “Selector” window”on page18.
Select Watt Pilot from a list and click “File->Connect”. Program will update controller firmware if necessary. Usually this process is automatic
and does not require any action, just wait until “Firmware upgrade was
successful!” message appears. If problems arise with firmware update,
see “Firmware update” on page 30 and “TROUBLESHOOTING” on page
62.
Once connected to Watt Pilot, dialog will popup informing that no calibration file is found for new attenuator:
10. Click “Finish” to end installation. Program cannot be opened if only
drivers were installed (see step 2 for details).
Figure 4. Dialog box, shown if Watt Pilot calibration file is not found.
Select “Yes”, calibration window will appear. Use instructions in section
“Calibration” on page20 to setup calibration. After calibration is done,
“Watt Pilot control” window will appear. Use slider to select and set
required power. See section “Watt Pilot “Control”window” window on
page22if more information is needed.
• Serial Number
This column shows unique Watt Pilot controller hardware serial number. It is used to identify hardware at low level. Use “Options->Watt Pilot
Name...” menu option in control window to give meaningful name to
attenuator.
• COM port
Each Watt Pilot gets unique serial port name after first enumeration with
computer. This column shows USB-serial port name assigned by Windows. COM port name is necessary to know for advanced users who
want to use serial commands in their applications. See chapter “Serial
commands and protocol” on page46 for more details about this.
• Status
This column shows “Connected” if attenuator control window is active
otherwise it is blank.
Calibration procedure:
“File” menu description:
• Connect
This opens control window for selected Watt Pilot, it does the same as
double clicking in device list. If only one device is connected during program startup, control window will be opened automatically. See chapter “Watt Pilot “Control”window” on page 22 for information.
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2. Check checkbox in “Step 2” if using “Big aperture” waveplate rotator.
See pictures below.
• Close
This will close Watt Pilot “Selector” window, but leaves control windows
opened if any.
• Exit
This will close Watt Pilot “Selector” window, and all control windows too.
“Help” menu description:
6
1. Click “GO” button in section “Step 1” and wait till motor stops. This will
drive waveplate holder to hardware zero limit switch. This will allow accurate homing from control window. Homing is needed after power
loss during motion and will eliminate any accumulated position error.
• Search For Devices
This will force searching for Watt Pilot devices attached to computer. It
can help if not all devices are detected and listed automatically.
4.4. Wat t P i lot “ S e l e c to r ” w i n d o w
Watt Pilot “Selector” window contains a list of currently connected and
powered attenuators. This window is used to choose device to work
with if there are several controllers connected to single computer. Functions of this window are described in the picture below.
Figure 6. Calibration window.
• User Manual
This will open this help file.
Standard rotator. “Step 2”
checkbox must be unchecked
“Big aperture” rotator. “Step 2”
checkbox must be checked
Figure 7. Standard and “Big aperture” waveplate rotators.
3. Rotate waveplate by using buttons in section “Step 3”, and measure
laser power after the attenuator. Number on the buttons represents motor moving distance (measured in stepper motor steps) and rotation direction. One step equals to 0.0115 degrees for standard waveplate rota-
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tor and 0.005 degrees for big aperture attenuator, using default settings.
It is advisable to search for lowest power (max attenuation) position, because usually it can be spotted more easily and accurately. Power meter
is not necessary for relative, coarse power attenuation, min power can
be found using visualizer.
4. Select appropriate option in “Step 4” when minimum or maximum
power is found. Angular offset is recalculated and shown in “Step 7” field
every time “Step 4” selection is clicked. At this moment, main calibration
goal is completed and “Apply” button can be clicked to apply changes.
Further steps are optional, but can be set for convenience.
5. Calibration result can be verified using buttons in “Step 5” panel. Usage example: click “Drive to minimum power” button and wait till rotator
stops. Use buttons “-10” and “10” (located in “Step 2”) to ensure if current
position is really of lowest power. If it is, click “Apply”, else select “Minimum power” in “Step 4” again, to redefine offset. The same can be done
with maximum power point. Checking both min and max positions in
“Step 5” makes no sense.
6. Non-ideality of polarizers and waveplate will cause losses, so 100 %
percent transmission will pass less energy than available, and 0 % transmission actually does not block all radiation. Real maximal and minimal
transmitted power can be measured while calibrating Watt Pilot, in “Step
5”. These extreme values should be entered in relevant fields of “Step 6”.
For example, one uses 1 W laser, and 20 mW is measured as minimal
power, and 0.99 W as maximal power. So it is handy to check “Use absolute power measurement units”, put value “0.02” into field “Minimum
measured value:”, “0.99” into “Maximum measured value:”, and write “W”
into “Enter measurement units to use:” textbox, because measurement
units are “Watts”.
7. Click “OK” button to accept calibration or “Cancel” to discard. If dialog,
asking to home will appear, answer “Yes” for correct device operation.
4 .6 . Wat t P i lot “Co n t r o l” w i n d o w
This window is used to change laser power after Watt Pilotattenuator.
Calibration procedure must be finished before correct attenuator operation. Main components of this window are described below.
• Watt Pilot name and serial number is shown on each attenuator control
window caption.Watt Pilot can be renamed by “Options -> Watt Pilot
Name…” menu option. Name is convenient if more than one device is
used in the same system. Name length can be up to 20 characters and
is saved into controller memory. Serial number is unique for each Watt
Pilot controller and cannot be changed as it is used to identify hardware
at low level. Please include serial number if contacting developers.
• Power meter panel always shows existing power after the attenuator.
Percentage range is from 0 % to 100 % of transmission. Zero percent
means that waveplate occurs at 45 degrees angle, beam polarization is
rotated by 90 degrees and is maximally attenuated. Display reading “100
%” means that waveplate is rotated at minimum attenuation – maximum transmission angle.
Figure 9. Power meter panel: Left - “Use absolute power measurement units”
checkbox is set in “Options->Preferences”, right - checkbox is unset.
If “Use absolute power measurement units” checkbox is set in “Options->
Preferences” or during calibrating, numeric display, showing “mW” becomes active. Absolute power reading is converted from percentage
value with respect to minimal and maximal measured power using
power meter. Correct min and max power values must be set in program preferences or calibration windows.
• Lower slider changes power from 0 % to 100 % in 0.25 % steps. Values
in lower numeric fields will alter according to slider position. There is
a triangle-shaped marker above lower slider which shows power currently set in real-time – the same as “power meter panel”displays. Both
options “Automatically execute “GO” after…” must be selected in “Options-> Preferences…” if power should be set immediately after slider
move. Otherwise click “GO” button to actually set power.
• Enter required value (%) field is used to manually enter percentage of
Watt Pilot transmission. Decimal point symbol is “.” (dot), two decimal
places can be used. Valid range is 0.00 % .. 100.00 %. Option “Automatically execute “GO” after required power change” must be selected in “Options-> Preferences” if waveplate should rotate automatically after value
of this field is changed. Otherwise click “GO” button to actually set power.
• Absolute required power field is available if “Use absolute power measurement units” option is set in “Options-> Preferences…” or “Options->
Calibration…”. Decimal point symbol is “.” (dot). Valid range is from “Minimum measured value” to “Maximum measured value” set in program
preferences. Option “Automatically execute “GO” after required power
change” must be selected in “Options-> Preferences” if waveplate should
rotate automatically after value of this field is changed. Otherwise click
“GO” button to actually set power.
• Preset buttons can be used to quickly set predefined output power.
Left click on any of them and appropriate value will appear in (4) or (5)
text boxes. If Option “Automatically execute “GO” after required power
change” is selected in “Options-> Preferences”, waveplate will rotate automatically, otherwise click “GO” button to actually set power. In order to
edit preset values, right click on any preset button. “Edit Preset Buttons”
window will appear:
Output power level is always shown as percentage
because it is directly related to waveplate angle
2. “Power meter panel” Shows output power value,
at which attenuator is currently set to
Power also can be shown with absolute measurement units if correctly set in program preferences
6. Preset buttons instantly change required power
4. Enter required power level here in percent.
Click “GO” to set
Upper indicator represents actual power level
5. Absolute required power field is used to set
power level using known units if correctly set in
program preferences
3. Move lower slider to change required power
level. Click “GO” button to apply it
10. This will drive waveplate to “Home” position, set
by calibration process and preferences
9. Hold this button to
constantly decrease
power
8. Immediately stops Watt Pilot rotation
9. Hold this button to
constantly increase
power
7. Click “GO” to apply
power level which is
shown in text boxes
Figure 8. Watt Pilot “Control” window. Currently laser power is set to 5.05 mW or 50 % of full calibrated range. Measurement units are available because absolute
minimal and maximal power values are set in program preferences during calibration process.
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• Close This Window
This will disconnect from Watt Pilot and close active “Control” window.
“Options” menu description:
• Calibration…
This will open Watt Pilot calibration window. See chapter “Calibration” on
page 20 for details.
• Preferences…
This will open program configuration window. See chapter “Program
preferences description” on page 26 for details.
• Watt Pilot Name…
This will open “Rename Device” window. Use up to 20 characters for
name. Enter new name and click “OK” to accept.
Figure 11. “Rename Device” window.
“Motor Settings” submenudescription:
Figure 10. “Edit Preset Buttons” window. Currently preset values are 0%, 25%,
50%, 75%, 100% of transmission, because checkbox is unchecked. Otherwise all
values would represent absolute power in user selected units.
Option “Use absolute measurement units for preset buttons” will be enabled only if measurement units are correctly configured in “Options->
Preferences…”. If checkbox is set, clicking on preset button will update
“Absolute required power field (5)”, else “Enter required value (%) field (4)”
will be updated with value displayed on button.
• “GO” button. Click to set power (rotate waveplate).
• “STOP” button will cancel rotation.
1. Watt Pilot name
and serial number
• Show Device Selector
This will open Watt Pilot “Selector” window.
• Buttons “<<” and “>>” will continuously decrease/increase power. Controller firmware must be up to date for these buttons to appear. These
buttons are not available for controllers with serial numbers beginning
with “4ATT”. If “Rotate continuous” option in program preferences is set,
waveplate can be rotated to any angle, otherwise waveplate motion is
restricted to 0..45 degrees.
• “Home” button will drive waveplate rotator to home limit switch and
back to “Home position”, set in “Options-> Preferences…”. Usually this
should be executed every time when device is turned on.
“File” menu description:
• Save Calibration…
Current program settings can be saved to file. Configuration file includes
all options in “Options-> Preferences”, preset values and calibration offset. Run time program configuration files are saved in folder “Application
data for all users\Altechna\Watt Pilot\Settings”.
• Set Safe Settings
This option will set waveplate rotator angular velocity to 8.73 deg/s, with
acceleration and deceleration on. Such motor settings should be used if
“Optimized settings” causes motor to stall or miss steps. Such problems
may arise with old worn-out attenuators. Attenuation from 0 % to 100
% is changed in 7 seconds. These timings apply to “Standard” (small aperture) waveplate rotator.
• Set Optimized Settings
This will set waveplate rotator angular velocity to 14.076 deg/s, no acceleration and no deceleration. This is more faster motion than “Safe
settings”. Attenuation from 0 % to 100 % is changed in 3.19 seconds.
Waveplate turns 360 degrees in 25.6 seconds. These timings apply to
“Standard” (small aperture) waveplate rotator. All new attenuators will
perfectly work with such option selected.
• Advanced…
“This will open “Motor settings” window, where motor speed can be
tweaked. It can be used for trouble shooting or to find optimal working
point between optimal and safe.
“Help“menu description:
• User Manual
Show this help file.
• About…
This will show software version and contact information. Please include
software version and controller serial number when contacting manufacturer.
• Load Calibration…
Program settings can be restored from file. Configuration file includes all
options in “Options-> Preferences”, preset values and calibration offset.
Current configuration will be overwritten.
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4 .7 . P r o g r a m p r e f e r e n c e s d e s c r i p t i o n
4.8. M oto r s e t t i n g s d e s c r i p t i o n
Preferences window can be accessed by “Options->Preferences” menu
item in Watt Pilot control window.
Motor settings can be accessed from “Watt Pilot Control window” by
“Options-> Motor Settings-> Advanced…”. These settings are for advanced users only. Security passphrase for motor current controls is
“I understand”.
Figure 12. Program preferences window.Can be found under menu “Options>Preferences”.
a)
• Rotate continuous. If checked, waveplate can be rotated continuously
using “<<” or “>>” buttons in control window. This will cause attenuation
to change from min to max 8 times in 360 degrees turn. This option can
be useful to check if current waveplate calibration is set for best contrast
ratio possible. For example, best contrast can be get if using second or
third 45 degree slot. For this option to appear, controller firmware must
be updated to latest. This option is not available for controllers with serial numbers beginning with “4ATT”.
• “Home” position. Power can be set to max or min power after “Home”
button clicked.
• Automatically execute “GO” after required power change. This allows
waveplate to rotate automatically if required power was changed by
editing values in numeric fields.
• Automatically execute “GO” after slider change. This allows waveplate
to rotate automatically if required power was changed by moving the
slider. “Automatically execute “GO” after required power change” must be
checked for this options to be enabled.
• Use absolute power measurement units. Setting this will enable power
to be measured with absolute measurement units.Minimum and maximum power values must be known for this option to work. This setting
can also be changed in “Calibration” window.
• Measurement units to use. Alphanumerical string can be entered here
to represent measurement units. Default is “mW”, but can be changed to
“uW”, if working with “micro watts”.
• Minimal and Maximal power meter reading. These fields must be filled
with minimal and maximal measured power values. Decimal separator
symbol is dot (“.”). These values will appear as available power range in
main window.
• Use absolute measurement units for preset buttons. If this is set, preset button values are shown as absolute power values, otherwise, preset button values mean % of transmitted power. Option “Use absolute
power measurement units” must be set for this option to be enabled.
Preset button values are recalculated automatically with respect to min
and max measured power.
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b)
Figure 13. “Motor settings” window: a) Controller with latest firmware and serial
number beginning with “5ATT” or “6ATT”; “Optimized” settings are applied. b)
Controller with outdated firmware or serial number beginning “4ATT”; applied
“Safe” settings. Passphrase “I understand” is entered in security field so motor
current can be adjusted.
• Motor Enabled checkbox. If unchecked, no current flows through the
motor windings. Default is checked.
• Resolution. Stepper motor can be driven in microstepping mode, so
one motor step can be physically divided into 1 - no microstepping,
2 – half microstepping, 4, 8 or 16 microsteps. That means, that standard
waveplate rotator can have resolution of 15600, 31200, 62400, 124800
or 2496000 steps per full turn. Big aperture waveplate holder can have
36000, 72000, 144000, 288000, 576000 steps per full turn resolution. No
microstepping can cause motor resonance problems. The higher the
resolution, the smoother and quieter motor is, but motor torque and
speed will decrease. Half stepping resolution is used as default.
ignored, and motor is enabled or disabled depending on selection to
the right. Ask document “Watt Pilot User manual for advanced users”
from supplier.
• Overwrite Dir Input option is used in “Step-Dir” mode only. If checked,
voltage level on “Dir” pins 2 and 10 in DB15 connector is ignored, and
motor direction is set depending on selection to the right. Ask document “Watt Pilot User manual for advanced users” from supplier.
• Motor current settings. Setting motor current higher than default can
cause permanent damage to motor or controller, so current changing
sliders are disabled by default. In order to activate them, please enter
string “I understand” (without quotes) in security text field. Motion current is used when motor rotates waveplate, so it must be higher than
standby current. Standby current is used when motor idles. Additional
“STEP/DIR” current slider is present for controllers with serial numbers
beginning with “4ATT” or newer controllers with outdated firmware version. This current drives motor continuously when controller operates
in “Step-Dir” mode and motor is enabled by “Enable” signal on DB15
connector or by enable overwrite command. Motor current is cut off
completely if enable signal is lost. In analogy with this, “Motion” and
“Standby” current values are used for controllers with serial number
“5ATT” or “6ATT”, so third slider is hidden. Third slider should be used only
by advanced users and does not relate to watt pilot attenuator directly.
Default motion current is 0.95 A for standard and big aperture attenuators, standby current is 0.3 A by default.
• Write settings button. Click this button to save configuration into controller memory. Currently displayed settings will be reloaded after controller power cycle. If this button is not used, previously saved changes
will be loaded after controller restart.
4 .9 . F i r m wa r e u p d at e
Once connected, Watt Pilot software checks firmware version on device,
and updates it if necessary. Progress bar will popup informing user that
firmware update is in progress and one must wait until flashing process
is finished.
Figure 14. Normal firmware update process finish is indicated by “Firmware
upgrade complete” message.
Itwill take up to one minute and requires that user do not disturb update process. This process is not cancellable. Do not disconnect USB or
power supply cables, do not shutdown the computer. This window can
appear after “Watt Pilot” software is updated, because latest firmware
comes with Watt Pilot installer file. Confirmation message will appear
after update is completed, click “OK” and program will continue as usual.
If firmware upgrade window is different than shown here, see “TROUBLESHOOTING” chapter on page 62.
• Read settings button. This will load configuration from controller.
5 . WATT P ILOT CONTROLLER HARD WARE
5 .1 . Co n t r o l l e r s p e c i f i c at i o n s
Watt pilot controller isbipolar stepper motor driver with specifications
listed in Table 1 below.
Advanced feature is “STEP/DIR INTERFACE” connector, which enable
controller to be used with custom electronics, not only computer based
applications.
Table 1. Controller specifications.
Characteristic
Rating
Max output voltage
+12 V
• Step frequency. Motor step frequency, so waveplate angular velocity can be changed. Step frequency f [Hz] can have discrete vales such
as=8000000/(65535-n) , where “n“is integer in range of 1 .. 64000. Waveplate angular velocity ω [degrees/second] is equal to ω=360/(k∙r)∙f.Parameter “k” is 15600 for standard attenuator, and 36000 for big aperture
attenuator. Resolution divider “r”can be 1, 2, 4, 8 or 16, as mentioned earlier in “Resolution” description.“Safe” step frequency is 759.4 Hz, “optimized”
step frequency is 1224.2 Hz, but can be tweaked for best performance.
Max output current
2A
Current regulation type
Pulse Width Modulation
Microstepping capability
Full, Half, Quarter, Eight, Sixteen steps
Step frequency
Up to 4 kHz
Position feedback
Open loop operation (no external
position feedback encoder)
• Accelerate and Decelerate. If this option is set, motor gradually accelerates till maximum frequency is reached or decelerates till stop. This can
help to solve stall problems on worn out mechanics, but causes motion
to last longer. These options should be unchecked for normal usage.
Default is unchecked.
Controller protection
Driver have overheating and over
current (2A) protection
Device can be operated by
• Step Dir pulses
• Computer software via USB port
• Microcontroller via UART connection
• Overwrite Enable Input option is used in “Step-Dir” mode only. If
checked, voltage level on “Enable” pins 3 and 11 in DB15 connector is
Limit switch
One limit switch can be connected
and used only for homing
5V TTL
signals
USB
Microcontroller with
UART port or Step/
Dir signal generator,
can be connected to
D-SUB15 connector in
order to control motor
Interface, logic,
signal generation
12V/2A power supply
Bipolar stepper
motor driver
Computer with USB
port. “Watt Pilot”
software or self-written
software can control
attenuator or motor
Waveplate rotator or
other bipolar stepper
motor can be driven
Home
position
switch signal
Figure 15. Illustration of Watt Pilotcontroller advanced features.
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5 .2 . Co n t r o l l e r co n n e c t i o n s
Watt Pilot front and rear connectors are shown in the pictures below.
• Controller power supply socket. Plug dimensions: outer diameter - 5.5
mm (GND), central pin diameter - 2.1 mm (+12 V). Watt Pilot requires
+12 VDC/2 A power supply.
• “ON/OFF” switch. Green led indicatesthat controller is ON.
• “MOTOR” connector, 9 pin D-SUB female. Connect it to Watt Pilot attenuator. See ““MOTOR” connector pin out” on page 40for more information
N OT E
Figure 16. Controller front view.
• USB connector is used to control Watt Pilot with computer.
• Firmware upgrade button is hidden under small hole, highlighted by
arrow. Used to recover if firmware upgrade process crashed. See “TROUBLESHOOTING” on page 65if necessary.
• “STEP/DIR INTERFACE” connector can be used to control Watt Pilot
with microcontroller via UART or “Sep-Dir” pulses. See section Operation
modes: “Step-Dir” mode on page 34.
Controller can be used to drive variety of bipolar stepper motors, not
onlyWatt Pilot attenuator. For example most linear stages are driven by
stepper motors, so these controllers can be used to control them. See
“Supported Stepper Motors” on page41 about such capability.
5.3. Co n t r o l l e r i n t e r n a l b lo c k d i a g r a m
Watt Pilot controller consists of three blocks. Each is shown in Figure 18.
• Motor driver. This block drives motor by controlling currents in motor
windings, according to Step/Dir/Enable and motor power signals.
• Command parser. This block parses commands, acquired from USB or
UART, depending on switch A state (SWA). The state of switch A can be
changed by logic level on input “UartOn” in “STEP/DIR INTERFACE” connector. Also this block can select which Enable and Dir signals to use in
“Step-Dir” mode: internally generated or picked up from “STEP/DIR INTERFACE” connector pins. Switch E and F are used for this purpose.
Figure 17. Controller rear view.
• Internal Step/Dir signal generator. This block generates acceleration,
continuous speed and deceleration step pulses. Also DIR and enable
signals when controller is working in “Command” mode.
5 .4 . Op e r at i o n m o d e s : “Co m m a n d ” m o d e
This is thefirstof two possible controller operation modes.“Command”
mode is selected if pin5 (ModeSel) is left unconnected in front “STEP/
DIR INTERFACE” connector.
Motor position is set by sending ASCII commands to controller. Controller has USB and UART interfaces for communication. “STEP”, “DIR”,
“ENABLE” inputs are disconnected in this mode. Watt Pilot appears as
“virtual serial port” in computer device list when connected. “Watt Pilot”
software uses this port to change attenuation. It is easy to write own
program to integrate with controller. Device can be accessed by any
serial port program. USB drivers are available for Windows, Windows CE,
Mac or Linux (see “List of supported operating systems for USB drivers”
on page 44). Serial commands are listed in “Serial commands and protocol” on page46.
1
15
9
Figure 19. “STEP/DIR INTERFACE”15 pin D-SUB female connector on the
controller case
Table 2. “STEP/DIR INTERFACE” connector pin out.
Type
1
Step (A)
In (Optocoupler anode)
2
Dir (A)
In (Optocoupler anode)
3
Enable (A)
In (Optocoupler anode)
4
ZeroPosC
Open Collector
5
ModeSel
In (Pulled up to +5 V)
6
UartOn
In (Pulled up to +5 V)
7
UartRx
In
8
Not Connected
UART pins are connected directly to controller’s microprocessor, which
is 5 V device. RS232 to 5 V UART converter must be used to connect device to PC, for example, MAX232 chip can be used for this.
9
Step (K)
In (Optocoupler cathode)
10
Dir (K)
In (Optocoupler cathode)
11
Enable (K)
In (Optocoupler cathode)
5 .5 . Op e r at i o n m o d e s : “ S t e p - D i r ” m o d e
12
ZeroPosE
Open Emitter
13
GND
Controller ground
14
UartTx
Out
15
+5 V
Power output
Apart from USB, UART connection is available in “STEP/DIR INTERFACE”
connector. It can be used to communicate with microcontroller or prolong cable length with RS232 level shifter. See ““STEP/DIR INTERFACE”
connector pin out and specifications” on page35.
AT TENTI O N !
“Watt Pilot” software only supports “Command” mode and only via USB
connection. It will not work if RS232 level shifter is used.
AT TENTI O N !
AT TENTI O N !
Motor current is set by “ENABLE” signal, so leaving it high can overheat
the motor, so proper “ENABLE” handling must be implemented (by wiring or by using commands).
AT TENTI O N !
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8
Name
USB connection and computer are not necessary in this mode.Motor rotates according toelectric signals applied to “STEP/DIR INTERFACE” connector. These signals are called “STEP” (pins 1, 9), “DIR” (pins 2, 10), and
“ENABLE” (pins 3, 11). “DIR” signal sets rotation direction of the motor (0
V – motor rotates counterclockwise, +5V – motor turns clockwise). Voltage transitions from 0 V to +5 V on “STEP” input advances motor per one
step. +5 V on “ENABLE” pin will reduce motor current to “Standby current”
value set in settings and “STEP” signal is ignored. Otherwise, “Motion current” flows to motor and “STEP” pulses rotate the motor. Use “ENABLE”
input to reduce motor heating. More details can be found in ““STEP/DIR
INTERFACE” connector pin out and specifications” on page 35.
12
“STEP/DIR INTERFACE” connector is used to operate controller in “StepDir” mode or use UART interface instead USB. The type of connector is
15 pin D-SUB female.
Pin No.
This is the second of two possible controller operation modes.“StepDir” mode is selected by connectingpin 5 (ModeSel) to pins 13 (GND) in
“STEP/DIR INTERFACE” connector.
Figure 18. Block diagram of Watt Pilot controller.
5 .6 . “ STE P / DIR INTERFACE ” co n n e c to r p i n o u t a n d
s p e c i f i c at i o n s
In case controller with serial number “4ATT” or controller “5ATT”, but with
outdated firmware is used, “STEP/DIR current” value is used if motor
enabled. If “ENABLE” pin is high, motor is completely disconnected. This
caused lack of holding torque on idle state and step position could be
lost. This was fixed for “5ATT” controllers in firmware version v8 released
on August 22, 2012 and newer controllers. “STEP/DIR current” setting is
abandoned in latest controllers.
Table 3. “STEP/DIR INTERFACE” connector electrical specifications
Input pins
Description
UartRx
UartTx
UART baud rate 38 400, 8 data bits, 1 stop bit, no parity.
RXD and TXD pins are +5 V compatible with reference to
GND pin. Maximum input voltage is +5.5 V
Step/Dir/En
These pins are optically isolated, 3.3 V – 5 V compatible.
Input current requirement per pin:
4.6 mA @ +2.8 V
5.2 mA @ +3.3 V
6.8 mA @ +5 V
ModeSel
UartOn
These logic pins are 5V compatible with reference to
GND pin. Maximum input voltage is +5.5 V
Below is the description of “STEP/DIR INTERFACE” pins.
• Step (A), Step (K). +3.3 V - 5 V compatible input to optocouplers anode
Step (A) and cathode Step (K). Rising edge on Step (A) pin with reference
to Step (K) advances motor by 1 step in “Step-Dir” mode. Motion direction depends on Dir signal level.
All stepper motors suffer from resonance. Watt Pilot rotator tends to
resonate at frequencies from 100 to 300 Hz, so such low “STEP” frequencies should be avoided in “Step-Dir” mode. Vibration can be eliminated
by setting higher micro stepping in settings.
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It is necessary to mention that motor shaft is inert. Frequency of STEP
signal should be controlled linearly, especially at high motor speeds.
Motor should accelerate and decelerate smoothly. For instance, control
logic must sweep down STEP frequency before changing DIR level. Similarly, frequency must be swept up then reaching high motor speed.
“Step-Dir” mode signal timing requirements are shown in Figure 20.
Figure 21. Zero position input circuit diagram for controllers with serial numbers starting with “6ATT”.
Only mechanical limit switch can be attached to “4ATT” or “5ATT” controllers, because input circuit is different from “6ATT” controllers, it is
shown in the picture below.
Symbol
Description
Min.
Typ.
Max.
Unit
tA
ModeSel wait time. Controller switches to “Step-Dir” mode
after ModeSel pin goes low
1
s
tB
Wait time for first valid STEP pulse after “En” pin goes low
20
ms
tC
Time constant then motor current reaches motion current
value after “En” pin goes low
15
18
20
ms
tD
Time constant then motor current reaches stand by current
value after “En” pin goes high
15
18
20
ms
tE
STEP pulse period
35
µs
tF
STEP high-level time
5
µs
tG
STEP low-level time
10
µs
tH
DIR setup time
5
µs
tI
DIR hold time
7
µs
Figure 20. “Step-Dir” mode input signal timing requirements.
• Dir (A), Dir (K). 3.3 V - 5 V compatible input to optocoupler anode Dir
(A) and cathode Dir (K). This input controls motor direction in “Step-Dir”
mode. +5 V on Dir (A) pin with reference to Dir (K) sets motor direction
clockwise. This input can be overridden by command parser – see “Serial commands and protocol” on page 46 and Figure 18(SW F) on page
33 for details.
• Enable (A), Enable (K). 3.3 V - 5 V compatible input to optocoupler anode Enable (A) and cathode Enable (K). This input reduces motor current
in in “Step-Dir” mode. +5 V on Enable (A) pin with reference to Enable
(K) reduce motor current to “Standby current” value set in controller settings. Otherwise, “Motion current” flows to motor and “STEP” pulses rotate the motor.This input can be overridden by command parser – see
“Serial commands and protocol” on page 46 and Figure 18 (SW F) on
page 33 for details.
AT TE NTI ON !
Motor current is set by “ENABLE” signal, so leaving it high can overheat
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the motor, so proper “ENABLE” handling must be implemented (by wiring or by using commands).
AT T E N T IO N !
Figure 22. Zero position input circuit diagram for controllers with serial numbers starting with “4ATT” and “5ATT”.
WA RNI NG !
“6ATT” controllers support every Watt Pilot attenuator, but “6ATT” attenuator cannot be driven by “4ATT” or “5ATT” controller.
NOTE
Because of mechanical zero position switch, zero position optocoupler
signal should be debounced or used only first voltage spike detected for
accurate zero position detection.
In case controller with serial number “4ATT” or controller “5ATT”, but with
outdated firmware is used, “STEP/DIR current” value is used if motor
enabled. If “ENABLE” pin is high, motor is completely disconnected. This
caused lack of holding torque on idle state and step position could be
lost. This was fixed for “5ATT” controllers in firmware version v8 released
on August 22, 2012 and newer controllers. “STEP/DIR current” setting is
abandoned in latest controllers.
• ModeSel. Then this pin is connected to GND pin (13), controller switches into ”Step-Dir” mode. If this pin is left unconnected or applied +5 V
with reference to controllers ground (pin 13), Step/Dir/Enable inputs become disconnected and controller works in “Command” mode. ModeSel pin controls internal switches SW B, SW C, SW D (“Controller internal
block diagram” on page 33). ModeSel pin is not optically isolated and is
pulled up to internal +5 V (See “Watt Pilot controller connection examples and input circuit diagram” on page 42).
• ZeroPosC, ZeroPosE. These pins are used to sense zero position switch
state.Phototransistor is open (low resistance state) if pin 7 in “MOTOR”
connector is 0 V. and closed (high resistance) if pin 7 is +5V – logic
high.“6ATT” controllers come with attenuator, which optical sensor output is normally high, and 0 V if rotator is in zero position. Pin 7 is CMOS
input with absolute maximum voltage rating +5.5 V.
• UartOn. This pin controls internal switch SW A, which sets command
path to the command parser (“Controller internal block diagram” on
page 33). Then this pin is connected to GND pin (13), controller isaccessed by 5V UART interface (“UartRx” and “UartTx” pins) instead of USB
port. Useful, if controller is operated by user’s microcontroller/FPGA. All
“Command” mode commands are valid. If this pin is left unconnected or
applied +5 V with reference to GND, command parser gets commands
via USB port. UartOn pin is not optically isolated and is pulled up to internal (See “Watt Pilot controller connection examples and input circuit
diagram” on page 42).
AT TENTI O N !
“Watt Pilot” software only supports “Command” mode and only via USB
connection. It will not work if RS232 level shifter is used.
AT TENTI O N !
UART pins are connected directly to controller’s microprocessor, which
is 5 V device. RS232 to 5 V UART converter must be used to connect device to PC, for example, MAX232 chip can be used for this.
• UartRx, UartTx - 5 V UART input and output pins, see UartOn pin
description. These pins are not optically isolated. If galvanic isolation is needed, special integrated circuits can be used, for example
ADUM1201.
• GND. Ground pin of controller internal circuit it is reference for ModeSel, UartOn, UartRx and UartTx pins.
• +5V. Internal controller +5 V. Can be used for external circuitry and can
supply up to 25 mA of current.
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15
6 . W RITIN G SOFT WARE FOR WATT P ILOT
5 .7 . “ MOTOR ” co n n e c to r p i n o u t
5.8. S u pp o r t e d S t e pp e r M oto r s
“MOTOR” connector is used to connect bipolar stepper motor and home
limit switch to controller. The type of connector is 9 pin D-SUB female.
There are two types of stepper motors: unipolar and bipolar. Controller
supports bipolar stepper motors.In order touse unipolar motor as bipolar, center wires from both windings must be left unconnected.
5
1
9
6
Motor winding resistance multiplied by motor current must be less than
11.5 V. Controller can drive up to 2 A maximum current and 1.6 A continuous. ST2818S1006 stepper motor can be chosen as reference for motor
requirements, because it is used as waveplate rotator.
Figure 23. Controller “MOTOR” connector.
Unipolar stepper motor
Bipolar stepper motor
Table 4. “MOTOR” connector pin out
A
Com
(Yellow)
A\
B
Com
(White)
B\
Description
Controller serial number begins with:
Pin No.
1
“4ATT” ”, see
Figure 22 (p 39)
“5ATT”, see
Figure 22 (p 39)
“6ATT”, see
Figure 21 (p 38)
Motor winding B output (usually red wire)
2
Motor winding B\ output (usually blue wire)
3
Motor winding A\ output (usually green wire)
4
Motor winding A output (usually black wire)
5
No connection
6
7
Zero position switch return
No connection
GND
Zero position
CMOS input with
pullup to +5 V
+5V power supply for optical
sensor, up to 70
mA
8
No connection
Pull up to +5 V,
not used
9
Zero position switch
GND
Connector pin out changes were made in controller hardware revisions.
Only mechanical limit switch can be used with controller serial numbers
“4ATT” and “5ATT”, connected to pins 6 and 9. Latest Watt Pilots with
“6ATT” serial number come with optical home position sensor on rotator, so limit switch input circuit is essentially different from previous
hardware versions. See Figure 21and Figure 22 on page 38for differences. “6ATT” rotators are not compatible with “4ATT” or “5ATT” versions of
controllers. All versions of rotators can be used with “6ATT” controllers.
Motor wire
Controller pin
number
4
Leave
unconnected
3
1
Leave
unconnected
2
Figure 24. Using unipolar motor as bipolar.
6 .1 . L i s t o f s u pp o r t e d o p e r at i n g s y s t e m s f o r USB
drivers
In order to communicate with Watt Pilot, USB drivers are necessary.
These are available for more operating systems than “Watt Pilot” software.
Virtual USB-Com port drivers can be installed on Windows 2000 (32bit), Windows XP (32-bit), Windows Server 2003 (32-bit), Windows Vista
(32/64-bit), Windows Server 2008 (32/64-bit), Windows 7 (32/64-bit),
and Windows 8 (32/64-bit).
6 .2 . S e r i a l p o r t pa r a m e t e r s
Serial port parameters to be used are shown in a table below.
Table 5. Stepper motor ST2818S1006 electrical characteristics
Winding voltage
Winding Current
Winding Resistance
Table 6. Serial port parameters.
2.66 V
0.95 A
2.8 Ω
Resistance of motor windings usually is less than 10 Ohms, so wires to
the motor, must be as short as possible and with significant wire diameter (>0.75 mm2, or ≤20 AWG) to minimize wiring impact to motor noise.
5.9. Wat t P i lot co n t r o l l e r co n n e c t i o n e x a m p l e s
and input circuit diagram
Baud rate
Parity
Handshaking
Stop bits
38400
None
None
1
6 .3 . I d e n t i f y i n g s e r i a l p o r t n a m e
First step to control Watt Pilot using serial port and commands would be
to find out which serial port is assigned for device. This can be seen in
Watt Pilot “Selector” window list – see section “Watt Pilot “Selector” window” on page18.
In case only drivers were installed (no “Watt Pilot” software itself – see
“Computer requirements” on page12) serial port name could be checked
in Windows “Computer manager”. Right click on “My Computer” (1), select “Manage” (2). “Computer manager” window will appear. Click on
“Device Manager” under “Computer Management” tree (3) and look for
“Ports (COM and LPT)” (4). Each connected and powered on attenuator
appears as “Silicon Labs CP210x USB to UART Bridge (Serial port name)”.
Serial port name is shown in parentheses, as seen in the picture below.
Figure 25. Connecting external equipment to use Watt Pilot controller in “StepDir” mode.
1
3
4
Figure 26. Connecting Watt Pilot controller to microcontroller employing all of Watt pilot features
Figure 27. Finding Watt Pilot serial port name using Windows “Computer
Manager”.
www.altechna.com
Linux users can find Watt Pilot port by executing command “root |dmesg
| grep cp210x”:
There is no need to install any drivers on modern Unix-like (Linux, MAC)
operating systems. Watt Pilot is automatically recognized and installed
as “ttyUSB” device after connecting it to computer. You can check which
serial port is assigned in your UNIX machine with command „root
|dmesg | grep cp210x”.
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16
Third way to identify Watt Pilot is to open each serial port and send “p”
command. If attenuator is present on that port, it will send back string
starting with “USB”, as listed in “Serial commands and protocol” on page
46. If device is not present, no bytes will be received or received string
will not begin with “USB”. Serial port read timeout can be set to 50ms to
speed up scanning process. This method is universal and can be used
with any operating system. Read next chapters about serial port parameters and command list.
Figure 28. Finding Watt Pilot serial port under Linux. Screenshot is taken on
Slackware Linux 13.37 32 bit OS.
In the picture above we can see that one Watt Pilot (cp210x) device is
assigned to “ttyUSB0” port. There is also shown installation command for
“CuteCom” package, which is easy to use terminal application with GUI.
6 .4 . S e r i a l co m m a n d s a n d p r oto co l
Watt Pilot is a slave device according to computer and computer is a
master device. That means that PC sends data requests to attenuator,
and attenuator must respond. Watt Pilot itself will never send data to
computer without request, except of two cases: if “Report zero position”
command “zr” setting is set; also string “USB Mode\r\n” is sent upon controller start if controller starts in “Command” mode.
Watt Pilot controller writes all received bytes to internal buffer. If it receives “carriage return” symbol (or ‘\r’ in C++ denotation, 13’th symbol in
ASCII table, or 0x0D in hex), device will try to parse received bytes as a
command string and will execute it. Attenuator echoes back every byte
it receives back to computer except for ‘\r’. Symbol echoing is essential
for users who literally type commands in terminal window. This enables
user to see what data is sent to device, because not all terminal programs has a text field where sent symbols are shown. “\n” (0x0A) symbol
is treated like all other symbols.
Watt Pilot will respond to byte ‘\r’ by sending additional data, if command requires it. Additional data is terminated with “\r\n” symbols. Termination symbols “\r\n” are essential for users who literally type commands in terminal window. These symbols are not visible, but they
format “received data” window text so it looks organized.
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17
From computers perspective each command is ended by byte ‘\r’. “Enter”
key press usually sends this symbol in most of terminal programs. Command and command parameter is separated by space symbol (0x20).
For example, typing such string “g 3000” in terminal application and
pressing enter key on the keyboard will drive waveplate rotator to absolute position of 3000 steps. Here “g” (0x67) is a command, space (0x20)
is a separator, and “3000” (0x33, 0x30, 0x30, 0x30) is a command parameter, which corresponds to 3000 steps. All sent bytes in hexadecimal will
be (0x67, 0x20, 0x33, 0x30, 0x30, 0x30, 0x0D), including command end
symbol ‘\r’, or “Enter” key press. New command can be sent after 50 ms.
Example:
“i 625” – set coordinate to 625. Now send “so” to save
position to controller.
h
Resets coordinate counter to 0.
st
Stop motor smoothly if it is currently running.
This is preferred command to stop motor instead of “b”.
b
Bake movement immediately.
This command stops motor, but step counter accuracy can
degrade using watt pilot.
zp
Go to hardware zero position and reset step counter.
Use this command to return waveplate to its home
position, determined by zero position switch. Then motor
stops controller stores 0 in coordinate counter and saves
this value.
There is no command acknowledge in protocol, so 50 ms delays between commands must be inserted. Otherwise command misinterpretation can occur. See table below for command list.
Table 7. Serial commands list
Command
ent x
This command is effective only in “Step-Dir” mode.
Controls software disconnecting of “Enable” input pin
(switch SW E – see Figure 18).
Parameter x:
1 “Enable” pin is disconnected, motor is enabled.
0 “Enable” pin is disconnected, motor is disabled.
off motor power is controlled by signals on “Enable” input
pin in “STEP/DIR INTERFACE” connector.
Example:
“ent off” – motor power is controlled by input pin. Now
send “ss” to save this setting to controller.
dir x
This command is effective only in “Step-Dir” mode.
Controls software disconnecting of “Dir” input pin (switch
SW F – see Figure 18).
Parameter x:
cw “Dir” pin is disconnected, motor direction is clockwise.
ccw“Dir” pin is disconnected, motor direction is
counterclockwise.
off motor direction is controlled by signals on “Dir” input
pin in DB-15 connector.
Example:
“dir ccw” – set motor direction counterclockwise. Now send
“ss” to save this setting to controller.
mx
Move motor by x steps.
Parameter x:
Integer number. Can be positive (motor turns clockwise)
and negative (motor turns counterclockwise). Place “-“ for
negative notation. x can be in range of 2­ 147 483 646..+2
147483646.
Example:
“m 1000” to move 1000 steps clockwise and “m -1000” to
move 1000 steps counterclockwise.
gx
Go to absolute coordinate.
Parameter x:
Integer number. Can be positive and negative. Place “-“ for
negative notation. x can be in range of 2­ 147 483 646..+2
147 483 646.
Example:
“g -400” – motor turns while internal step counter reaches
400. Then send “m 1000” to move 1000 steps clockwise.
Now motor stands in 600 position.
ix
18
rx
Set motor micro stepping resolution.
Parameter x:
1 Motor is driven in full steps mode. Waveplate holder
turns once in 15600 steps for standard attenuator or
36000 for big aperture.
2 Half step mode. Waveplate holder turns once in 31200
steps.
4 Quarter step mode. Waveplate holder turns once in
62400 steps.
8 Eight step mode. Waveplate holder turns once in 124800
steps.
6 Sixteen step mode. Waveplate holder turns once in
249600 steps.
Higher micro stepping levels demonstrate better position
accuracy and no motor resonance. It is advisable to use
half stepping operation mode.
ws x
Set motor current then it is idles. This removes motor heat.
Some amount of current must be left in order to keep
position accuracy.
Parameter x:
Integer number in range of from 0 to 255. Motor current
can be calculated using such equation: I = 0.00835x (A)
wm x
Set motor current then it moves.
Parameter x:
Integer number in range of from 0 to 255. Motor current
can be calculated using such equation: I = 0.00835x (A)
wt x
Set motor current then controller operate in “STEP/DIR”
mode. There is no automatic current control like stand
by current in “USB” mode. Current can be cut only by
logic high on “Enable” input. This applies only for “4ATT” or
“5ATT” controllers with firmware version v7 or lower. This
command is absent for “5ATT” and “6ATT” controllers with
firmware v8 and higher.
Parameter x:
Integer number in range of from 0to 255. Motor current
can be calculated using such equation: I = 0.00835x (A)
Description
Set coordinate counter to specific value.
Parameter x:
Integer number. Can be positive and negative. Place “-“ for
negative notation. x can be in range of 2­ 147 483 646..+2
147 483 646.
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ax
Set acceleration.
Parameter x:
Integer number in range of from 0 to 255. 1 is the lowest
acceleration and 255 is the highest. 0 turns off acceleration.
Turning on acceleration helps to increase position
repeatability.
dx
Set deceleration.
Parameter x:
Integer number in range of from 0 to 255. 1 is the
lowest deceleration and 255 is the highest. 0 turns off
deceleration. Turning on deceleration helps to increase
position repeatability.
sx
[2] Boolean 1 or 0. Motor enable: motor is enabled if 1 and
motor is disconnected if 0. This setting is meaningful if
parameter [1] is On;
[3] Boolean 1 or 0. Status of switch SW F (see Figure 18). 1
means that “Dir” pin is disconnected and motor turns
clockwise if [4] parameter is 1 or counterclockwise
if [4] is equal to 0. If [3] is 0, then motor direction is
dependent on logic level on “Dir” input;
[4] Boolean 1 or 0. Motor direction: motor turns clockwise
if [4] parameter is 1 or counterclockwise if [4] is equal to
0. This setting is meaningful if parameter [3] is On;
[5]Reserved;
[6] Reserved;
[7] Reserved;
Response example (default controller settings):
swEn:0 en:1 swDir:0 dir:1 zr:0 zs:0 cs:0
Set maximal motor speed.
Parameter x:
Integer number in range of from 1 to 65000. Watt Pilot
waveplate rotation angular speed can be calculated using
such formula:
14400000
;
ω=
78r(65535–x)
Here ω – angular waveplate rotation speed (degrees per
second), r – micro stepping resolution – 1, 2, 4, 8 or 16.
Controller advances motor per one step in time intervals
equal to: T=(65535-x)/8 µs
p
pt
Show controller settings, related to “Command” mode.
Type this command only when using terminal and manual
command entering. This is the way to see fundamental
settings in “eye friendly” fashion. To get controller settings
for software programming, use “pc” command instead.
This command can be used to “ping” controller (to check
if controller is attached to particular COM port). If device
response to “p\r” string begins with “pUSB:“, it means that
Watt Pilot is attached and is turned on.
Return string (finished with 0x0A and 0x0D symbols):
USB: [1] a=[2] d=[3] s=[4] wm=[5] ws=[6] wt=[7] r=[8] en:[9]
zr:[10] zs:[11]
[1] Boolean 1 or 0. Current operating mode: “Command”
mode if 1, and “Step-Dir” mode if 0;
[2] Integer 0..255. Acceleration value;
[3] Integer 0..255. Deceleration value;
[4] Integer 1..65500. Speed value;
[5] Integer 0..255. Motor motion current value;
[6] Integer 0..255. Motor idle current value;
[7] Integer 0..255. Motor current value in “Step-Dir” mode;
[8] Integer 1, 2, 4, 8 or 6. Micro stepping resolution value
(full, half, quarter, eight or sixteen);
[9] Boolean 1 or 0. Motor enable: motor is enabled if 1
and motor is disconnected if 0;
[10]Boolean 1 or 0. Whether to report coordinate then
hitting zero position switch (if 1) or do not report (if
0). If this option is on (1), controller sends string “zp:
[integer_position]” on each zero position button press;
[11]Boolean 1 or 0. Whether to reset position counter on
each zero position switch press or no. If this option is
disabled (0), zero position button press does nothing
to step counter. If waveplate holder turned twice,
command “o” will show us that position is more than
15600 (15600 is full waveplate turn in full stepping
mode). If this position is enabled (1), position counter
will become 0 on each zero position switch press.
Response example (default controller settings):
USB: 1 a=232 d=232 s=55000 wm=114 ws=36 wt=114 r=2
en:1 zr:0 zs:0
Show controller settings, related to “Step-Dir” mode. Type
this command only when using terminal and manual
command entering. This is the way to see settings in “eye
friendly” fashion. To get controller settings for software
programming, use “pc” command instead.
Return string (finished with 0x0A and 0x0D symbols):
swEn:[1] en:[2] swDir:[3] dir:[4] zr:[5] zs:[6] cs:[7]
All returned parameters are boolean: 0 or 1.
[1] Boolean 1 or 0. Status of switch SW E (see Figure 18). 1
means that “Enable” pin is disconnected and motor is
enabled if [2] parameter is 1 or disabled if [2] is equal to
0. If [1] is 0, then controller output state is dependent
on logic level on “Enable” input;
pc
Show all controller settings, separated by semicolon (;). Use
this command when programming computer software to
read all settings.
Return string (finished with 0x0A and 0x0D symbols):
[1];[2];[3];[4];[5];[6];[7];[8];[9];[10];[11];[12];[13];[14];[15];[16];[1
7];[18];[19];[20];[21];[22];[23];[24];
Character meaning:
[1] Boolean 1 or 0. Current operating mode: “Command”
mode if 1, and “Step-Dir” mode if 0;
[2] Integer 0, 1, 2 or 3. Current motor run state: 0 – motor
is stopped, 1 – accelerating, 2 – decelerating 3 –
running at constant speed;
[3] Integer from 0 to 255. Acceleration value;
[4] Integer from 0 to 255. Deceleration value;
[5] Integer from 1 to 65500. Speed value;
[6] Integer from 0 to 255. Motor motion current value. I =
0.00835x (A);
[7] Integer from 0 to 255. Motor idle current value. I =
0.00835x (A);
[8] Integer from 0 to 255. Motor current value in “StepDir” mode. I = 0.00835x (A);
[9] Integer 1, 2, 4, 8 or 6. Micro stepping resolution value
(full, half, quarter, eight or sixteen);
[10] Boolean 1 or 0. Motor enable: motor is enabled if 1
and motor is disconnected if 0;
[11]Reserved;
[12] Boolean 1 or 0. Whether to reset position counter on
each zero position switch press or no. If this option is
disabled (0), zero position button press does nothing
to step counter. If waveplate holder turned twice,
command “o” will show us that position is more than
15600 (15600 is full waveplate turn in full stepping
mode). If this position is enabled (1), position counter
will become 0 on each zero position switch press;
[13] Boolean 1 or 0. Whether to report coordinate then
hitting zero position switch (if 1) or do not report
(if 0). If this option is on (1), controller sends string
“zp: [integer_position]” on each zero position button
press;
[14]Reserved;
[15]Reserved;
[16]Reserved;
[17] Boolean 1 or 0. Motor direction setting in “Step-Dir”
mode: motor turns clockwise if [17] parameter is 1 or
counterclockwise if [17] is equal to 0. This setting is
meaningful if parameter [20] is On;
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19
[18] Boolean 1 or 0. Motor enablesetting in “StepDir” mode: motor is enabled if 1 and motor is
disconnected if 0. This setting is meaningful if
parameter [1]is On;
[19]Reserved;
[20] Boolean 1 or 0. Status of switch SW F (see Figure 14). 1
means that “Dir” pin is disconnected and motor turns
clockwise if [17] parameter is 1 or counterclockwise
if [17] is equal to 0. If [20] is 0, then motor direction is
dependent on logic level on “Dir” input;
[21] Boolean 1 or 0. Status of switch SW E (see Figure 14).
1 means that “Enable” pin is disconnected and motor
is enabled if [18] parameter is 1 or disabled if [18] is
equal to 0. If [21] is 0, then controller output state is
dependent on logic level on “Enable” input;
[22]Reserved;
[23]Reserved;
[24]Reserved.
Response example (default controller settings):
1;0;232;232;55000;114;36;114;2;1;1;0;0;0;1;0;1;1;1;0;0;0;0;1;
o
zr x
zs x
en x
j
Return running state of the motor and current position.
Return string (finished with 0x0A and 0x0D symbols):
[1];[2]
[1] Integer 0, 1, 2 or 3. Current motor run state: 0 – motor is
stopped, 1 – accelerating, 2 – decelerating 3 – running
at constant speed;
[2] Integer in range of -2147483646..+2147483646. Current
motor position;
Response example:
3;4437
Use this command to determine if motor has done its
movement. After issuing any move command, poll “o”
command in time intervals about 250 ms and decode
response. If [1] parameter become 0, it means that motor
has stopped and is ready for next move command.
Report zero position when hitting zero position switch.
Parameter x:
1 Controller sends string “zp: [integer_value]” on each zero
position button press;
0 Turn off zero position reporting.
Reset coordinate counter then hitting hardware zero
position switch.
Parameter x:
1 Position counter will become 0 on each zero position
switch press;
0 Position counter increases position continuously.
Save settings of controller.
Save configuration mentioned in “pc” command
description to controller memory. Configuration saved by
“ss” command will be restored on controller power on.
sn x
Write 20 character long name to controller
Parameter x:
20 characters. If x is not 20 symbols, then returned name
can consist of unreadable characters. Please space pad
trailing name.
n
Show name.
Returns 20 character string, saved by “sn” command.
Return: 20 character string
Reset controller.
Controller resets in 4 s after issuing this command. It is
equivalent to power switch press. This command can also
enter into firmware upgrade mode if firmware upgrade
button is pressed. All changed settings and position are
restored in previous state, if “ss” and/or “so” commands was
not issued before reset.
Then controller starts, it sends string “STEP/DIR mode” or
“USB mode” according to state of pin “ModeSel”.
Turn off acceleration.
d0
Turn off deceleration.
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1
2
4
3
6
6.5. S o f t wa r e r e co m m e n d at i o n s
There are plenty of applications built for serial port communication.
Windows XP (and full installations of Windows 7 or Windows 8) has native “hypertrm.exe” terminal application, which can be launched by typing “hepertrm” in “Run” dialog (Winkey + R). Linux and OS X users can use
free “CuteCom” (http://cutecom.sourceforge.net) utility, see Figure 28 on
page46. For Windows OS it is recommended to use free tool “terminal.
exe” from https://sites.google.com/site/terminalbppFigure 29 (p 55).
5
Configure “terminal.exe” as follows:
Figure 29. “terminal.exe” window with “p” command sent.
1.Select correct com port number (see “Identifying serial port name” on
page 44);
2.Select correct serial port configuration values (see Table 6 on page
44);
3.Set “Hex” checkbox if received characters should also be shown as
hexadecimal values;
4.Click “Connect” button;
5.Type in command and press “Enter” key on keyboard. Command
string “p\r” is sent to device as shown in example picture. Look at “Serial commands and protocol” on page46 for available commands;
6.Watt Pilot response is shown in middle pane. Hex representation of all
received bytes is shown on the right. Controller “speed” setting is set
to “55000” as seen in example screenshot.
Presets can be configured for frequently used commands. Click “Set
Macros” button, “Macro Settings” window will appear.
Motor enable in “Command” mode.
Parameter x:
1 Motor is enabled.
0 Motor is disconnected.
a0
20
ss
Figure 30. Command string presets can be configured by clicking “Set Macros”
button in main “terminal.exe” window.
Type in string which should be sent, and name of this preset. Hexadecimal values can be entered with “$” prefix. For example command end
symbol “\r” [0x0D] should be entered as “$0D”. “Stop” command definition is shown in example. Click “Save” button to save your presets. “Stop”
button will appear in “Macros pane” of main window. Press it to stop
attenuator motor motion.
6 .6 . S e r i a l co m m a n d u s a g e w i t h N at i o n a l I n s t r u ments “LabView”
There is a „Serial port“ control in LabView. Add it to your LabView project
and set its properties to parameters listed in “Table 6” on page 44. Then
use commands described in“Serial commands and protocol” (p 46) to
control motor: use „g xx“, „m xx“ commands for moving, and „o“ command for checking if motor has stopped. To calculate motor step position for required laser power, use formulas, shown in in chapter “Relation
between motor position and laser power” on page56.
6 .7 . R e l at i o n b e t w e e n m oto r p o s i t i o n a n d l a s e r
power
Transmitted laser power ratio can be in range of 0.0 (max attenuation)
to 1.0 (min attenuation). According to Malus’ law, waveplate angle φcan
be calculated from “ratio”: φ = cos-1 (√ratio) (degrees). In order toget
motor step position “steps” from waveplate rotator angle φ, userelation
steps = φ ∙ k ∙ r, where coefficient “k” is “steps per unit”, depending on
waveplate rotator. k = 43.333 steps/deg for standard attenuator, and k =
100.0 for big aperture attenuator; coefficient “r” is controller’sresolution
parameter, it must be read from controller using “p” command”, or got in
“Watt Pilot” software “Options->Motor Settings->Advanced…”. “r” can be
1, 2 (default), 4, 8, 16 (microsteps per step). So motor step position “steps”,
using standard attenuator with default (unchanged from purchase) settings, can be calculated as:
steps = cos-1 (√ratio) ∙ 43.333 ∙ 2,
where “ratio” is required transmission (0.0 .. 1.0), “43.333” is “step per degree” for standard attenuator,and “2” is default resolution multiplier.
Usually arccosine function (acos()), found in programming packages operates with radians, so degrees must be converted to radians. Real relation between “ratio” and “steps”, used in “Watt Pilot” software is calculated
using following C# methods:
// Returns step position to be passed to “g steps” command.
// ratio – double in range 0.0 to 1.0.
publicInt32 GetStepPositionFromRatio(double ratio)
{
return GetStepPositionFromDegrees(GetAngleFromRatio(ratio));
}
// stepsPerUnit: 43.333 for standard attenuator or 100.0d for Big
aperture attenuator.
// resolution: 1.0d, 2.0d, 4.0d, 8.0d, 16.0d, depending on controller
settings.
publicInt32 GetStepPositionFromDegrees(double degrees)
{
double steps = degrees * stepsPerUnit *resolution;
return(Int32)steps;
}
// converts ratio (0.0..1.0) to waveplate angle in degrees.
// ratio – double in range 0.0 to 1.0.
publicdouble GetAngleFromRatio(double ratio)
{
double angle = ((Math.Acos(Math.Sqrt(ratio))) * 180.0) / (2.0 * Math.PI);
return angle;
}
Angular offset between waveplate and waveplate rotator is important,
so “degrees” parameter in GetStepPositionFromDegrees(double degrees) should be adjusted accordingly to offset, before passing.
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21
7 . WATT P ILOT ATTENUATOR DIMENSIONS
7 .2 . B i g a p e r t u r e at t e n uato r d i m e n s i o n s
7 .1 . S ta n d a r d at t e n uato r d i m e n s i o n s
Figure 33. Whole view of big aperture attenuator.
Figure 31. Mechanical drawings of Watt Pilot standard attenuator.All dimensionsshown in millimeters.
Figure 34. Mechanical drawings of Watt Pilot big aperture attenuator.All dimensions shown in millimeters.
7 .3 . Wat t P i lot co n t r o l l e r d i m e n s i o n s
Figure 32. Mechanical drawings of Watt Pilot standard attenuator (continued). All dimensions shown in millimeters.
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Figure 35. Watt Pilot controller dimensions.
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9 . LIST OF TABLES
8 . TROUBLESHOOTIN G
8 .1 . R e a l l a s e r p o w e r d o e s n ot m atc h s h o w n i n
s o f t wa r e
2. Progress bar on lower part of the window begins to fill, now program
is waiting for user to press “Firmware upgrade” button, which is located
inside controller box. Proceed to next step.
6. Click “OK” in “Firmware upgrade complete” messagebox. “Firmware
Upgrade” window will close and “Watt Pilot control” window will start.
Table 1. Controller specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 2. “STEP/DIR INTERFACE” connector pin out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Click “Home” button inWatt Pilot “Control” window. This eliminates angular error, which can occur if power is lost during waveplate motion.
8 .3 . F i r m wa r e u pg r a d e wa s u n s u cc e s s f u l o r i n terrupted
8 .2 . “ Upg r a d e co n t r o l l e r f i r m wa r e n o w ?” m e s s a g e a pp e a r s
In case firmware upgrade ended unsuccessfully due to some reasons
(cable disconnection, program crash…), usually such error will be
thrown then trying to use Watt Pilot.
Sometimes Watt Pilot software will show dialog, asking whether to update firmware:
Table 3. “STEP/DIR INTERFACE” connector electrical specifications. . . . . . 36
Table 4. “MOTOR” connector pin out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 5. Stepper motor ST2818S1006 electrical characteristics. . . . . . . . . . . 42
Table 6. Serial port parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table 7. Serial commands list.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 38. Error, thrown if device firmware becomes corrupted.
In order to recover, follow these steps:
Figure 36. Dialog, asking whether to update firmware.
This will appear if controller firmware cannot be updated without user
interaction and depends only on controller firmware version, not related
to hardware revision. It will pop up if controller has firmware version
prior to v8, released on August 22, 2012.These dialogs will newer show
up againonce firmware is updated.
3. Press and hold firmware upgrade button located under small hole
on controller’s front panel. This must be done in one minute, otherwise
process must berestarted. Firmware upgrade button is marked by yellow arrow in the picture below. It can be accessed with teeth stick, for
example.
1. Close “Watt Pilot”software;
2. Turn off controller using “ON/OFF” switch:
WAR NI NG !
Upgrade process cannot be interrupted! Do not disconnect USB, attenuator or power supply cables, do not shutdown the computer. Do not
use other devices while flashing. If upgrade is interrupted or unsuccessful, go to the end of this troubleshooter point to recover.
Follow these steps to update firmware manually:
Figure 37. “Firmware upgrade” button location inside Watt Pilot controller.
1. Answer“Yes” when asked about update dialog is shown in Figure 36.
“Firmware Upgrade” window will appear. Click “Upgrade Firmware” button:
4. Hold “Firmware upgrade” button pressed until confirmation about release will be displayed in “Firmware Upgrade” window as shown below.
Usually button must be held pressed up to 15 seconds. Process status is
displayed above progress bar.
3. Press and hold down “Firmware upgrade” button located inside controller box, see Figure 37 on page 64 to find there it is;
4. Turn on controller, while holding firmware upgrade button pressed;
5. Release button after 10 second after power on;
6. Launch “Watt Pilot” software and try to use the device;
7. Firmware will be correctly rewritten automatically. Device will be
ready to use after one minute.
5. Now wait till “Firmware upgrade was successful!” message appears.It
will take up to 1 minute to complete.
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27
WATT P ILOT
M oto r i z e d At t e n uato r
U S E R M A N UA L
Rev 3 November 2013
www.altechna.com
UAB Altechna • Mokslininkų st. 6A, 08412 Vilnius, Lithuania
Tel. +370 5 2725738 • Fax +370 5 2723704 • E-mail: [email protected]
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