astrojolo AstroLink 4 mini User manual

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AstroLink 4 mini

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Table of contents
Introduction ...................................................................................................... 4
Specifications ................................................................................................ 5
Getting Started .................................................................................................. 6
System requirements ..................................................................................... 6
Power supply considerations ........................................................................... 6
Installing drivers ............................................................................................ 7
Connecting device .......................................................................................... 8
PROG jumper ................................................................................................ 8
Basic operations ............................................................................................ 9
First time connect ...................................................................................... 9
3rd party software ................................................................................... 10
Board revisions ............................................................................................ 10
Revision 1 ............................................................................................... 10
Revision 2 ............................................................................................... 11
Connecting peripherals ..................................................................................... 12
Stepper focuser motor .................................................................................. 12
DC focuser motor ........................................................................................ 13
Sensors ...................................................................................................... 14
Power outputs ............................................................................................. 15
Regulated PWM outputs ................................................................................ 15
Regulated voltage output .............................................................................. 16
Manual control ............................................................................................. 17
Controlling components .................................................................................... 18
Connecting to device .................................................................................... 18
Focuser control ............................................................................................ 19
DC focuser control ....................................................................................... 22
Power outputs control .................................................................................. 23
Sensors and PWM outputs control .................................................................. 25
Other functions ............................................................................................ 28
3rd party software ....................................................................................... 29
Additional modules .......................................................................................... 31
Microstepping module .................................................................................. 31
Hand controller module ................................................................................ 32
Sky temperature sensor ................................................................................ 33
AstroLink charts ............................................................................................... 33
Overcurrent and overvoltage protection .............................................................. 36
Temperature compensation ............................................................................... 37
Compensation calculator ................................................................................... 38
Scripting support ............................................................................................. 41
Regulated voltage application ............................................................................ 43
Troubleshooting .............................................................................................. 44
Ground loops .................................................................................................. 46
How to check versions ...................................................................................... 47

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Software update .............................................................................................. 48
Firmware update .............................................................................................. 49

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Introduction
AstroLink 4.0 mini device has been created to make astrophotographers' life easier. This small box merges
several useful functionalities in one device:
·focuser stepper motor control (both bipolar and unipolar, Robofocus compatible. Microstepping available
with additional module)
·advanced temperature compensation with scripting support and compensation calculator
·DC focuser motor control (compatible with SW Motofocus)
·PWM regulated outputs to control dew/mirror heaters, fans or custom peltier cooling custom
adaptations with built in temperature controller
·12V switchable on/off power outputs to control setup components
·3-10V regulated voltage output
·temperature/humidity and temperature sensors to monitor these values, calculate dew point and control
heaters and peltier cooling
·sky temperature / cloud coverage sensor (optional)
·manual control with optional hand controller
·monitor voltage and current consumption plus energy consumed (for battery powered field setups)
·programmable overcurrent and overvoltage protection
·measured values charts
·compensation calculator
Device can be powered with DC voltage in range 11-14V. Total current drawn from all AstroLink 4 mini
outputs cannot exceed 10A. Device is controlled with dedicated software AstroLink 4 panel, but is also
exposed four ASCOM interfacesthat can be controlled with a 3rd party software in the same time
AstroLink 4 panel software is connected. ASCOM interfaces are also available for scripting to automate
acquisition process.

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Specifications
AstroLink 4.0 mini technical specifications.
Power supply 11-14V DC
Maximum current 10A
AstroLink power consumption less than 1W
Regulated PWM outputs 2 outputs RCA regulated 0-100%, 3A max. current single output
Switchable power outputs 3 outputs DC 5.5/2.1mm, 5A max. current single output
Regulated voltage output 1 output DC 5.5/2.1mm, 3-10V, 1.5A max. current (2.5A peak)
Focuser stepper output 1 output DB9, bipolar or unipolar stepper compatible
(Robofocus), 1.2A max. current (microstepping with additional
module)
Focuser DC output 1 output RJ9, SW Motofocus compatible, 1.2A max. current
Sensors inputs 1 DHT22 humidity/temperatures sensor input Jack 3.5mm, 1
DS1820 temperature sensor input Jack 3.5mm (optional sky
temperature sensor)
Manual stepper control input 1 input RJ9 (see manual for description)
Dimensions 147x92x36mm
Weight 190g
System requirements Windows 7 or above, ASCOM platform 6.2, .NET4.0 platform,
USB port
Device control - dedicatedAstroLink panel software
- ASCOM device drivers (primary focuser, DC focuser, Switch,
Observing Conditions)

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Getting Started
Before you start working with AstroLink device make sure your PC/laptop has at least one USB port
available and operates under Windows 7 or later. Second thing you need to have is power supplier. Please
see below a list of things to follow:
1. install AstroLink 4 panel software (installing software)
2. if you want to use 3rd party software install AstroLink ASCOM driver (installing software)
3. make sure the sensors are connected before turning on power supply (connecting device)
4. turn on power supply. You should hear a double beep after a moment (power supply considerations)
5. connect AstroLink with USB cable to PC/Laptop. After connecting USB cable you can hear several
beeps (unless PROG jumper is set to OFF - rev. 2.0 only)
6. start AstroLink 4 panel software. Use DIRECT connect or ASCOM connect mode to connect to device
(basic operations)
Details on connecting peripherals are described in Connecting peripherals chapter.
Details on using AstroLink 4 panel software are described in Controlling components chapter.
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System requirements
AstroLink 4.0 mini device requires a PC computer with Windows 7, 8 or 10 operating system (both 32 and
64 bit are supported) to work. Additionally the following software must be installed:
·ASCOM platform version 6.2 or above
·.NET framework 4.0
Device is connected to computer with USB port - both 2.0 and 3.0 is supported.
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Power supply considerations
Power supply is a key element of each electronic device. AstroLink was designed to be powered with single
power source and provide power to connected devices (focuser, camera, filter wheel, etc.). That's why
quality of the both power supply and connections is crucial. These elements must fulfill following conditions:
·power supply must be able to provide enough current to all connected receivers. But having at least 20%
of power margin is always a good idea, especially if we are not completely sure about quality and
parameters of the supply we have
·power supply must be regulated (provide constant DC voltage), and output voltage should not change
with changing of current that is drawn. It is especially important when using PWM regulated outputs for
high current receivers like dewcap heaters with large power consumption or peltier cooling devices
·number of cable connectors must be kept as low as possible. Each connector causes power loss and
voltage drop
·main power cable that provides power supply to AstroLink device must be kept as short as possible to
minimize voltage drop
·main power cable cross-sectional area must be kept large enough to prevent excessive voltage drop
AstroLink 4 mini device is provided with 2m long power supply cable with cross-sectional area 1.0mm2. This
is sufficient to all except most demanding applications, when you have both PWM outputs loaded with high
power receivers (for example two dew heaters, 50W total power). In this case it is advised to either make
short connection between AstroLink and power supply or replace power cable with the one of larger cross-
sectional area.

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Other option is to use external AstroLink module - Power Switcher, that can be purchased separately. This
module is capable to switch high power and can be powered from separate power supply.
Total current drawn from theAstroLink device cannot exceed 10A. There is 10A micro-fuse soldered to the
PCB that will break the circuit when over-current will be detected. If it happens, the micro-fuse would need to
be replaced. If the micro-fuse was burned due to reverse polarity or over-voltage it is also advised to replace
security transil diode, that could be damaged. It is 14V one direction transil diode type.
AstroLink interior (rev. 2)
Another topic worth consideration are ground loops in the astroimaging setup. You can read more about this
at Ground loops section.
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Installing drivers
Before connecting device to computer you need to install drivers. There is no need to install FTDI drivers in
advance, because Windows operating system should find them automatically after connecting AstroLink 4
mini to PC USB port. However, if FTDI drivers will not be found and virtual serial port will not be installed, you
need to download drivers from FTDI website and install them manually.
Software that needs to be installed is AstroLink 4.0 panel. This is standalone software that can control all
functionalities and settings of AstroLink device. Software can be downloaded at
http://astrojolo.com/astrolink website.
If you want to control AstroLink 4.0 mini components with a 3rd party software you need to install the
following additional driver:
·AstroLink Local Server driver (can be downloaded at website http://astrojolo.com/astrolink )
This package will install focuserASCOM driver that allows to connect to the device from a 3rd party software
like MaxIm DL, APT, FocusMax, SGP, CCDSoft and many others that support ASCOM drivers. The
following drivers will be installed:
·AstroLink 4m Focuser
·AstroLink 4m DC focuser
·AstroLink 4m Switch
·AstroLink 4m Observing Conditions
AstroLink Local Server driver allows to connect to the device multiple control software simultaneously. This
way you can for example monitor sensor values in AstroLink panel, control focuser with FocusMax and

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MaxIm, or any otherASCOM compliant software. Also scripting support is available for automation of
acquisition process.
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Connecting device
It is general rule of thumb to make all cable connections before turning on power. This also applies to
AstroLink device. However DC voltage outputs, PWM outputs, DC focuser output and stepper motor output
may be connected and disconnected when AstroLink is powered, however make sure twice that
corresponding output is turned off or idle when making connections.
AstroLink device is equipped with power cable ended with screw terminal to DC 5.5/2.1 adapter. This
adapter can be used as temporary solution for testing, it cannot handle current higher than 5A. For
permanent setup please consider changing it to the connection suited for your power supply output socket.
BROWN cable is positive - should be connected to power supply positive (+) connector
BLUE cable is negative - should be connected to power supply negative (-) connector
Sensors and remote controller must be connected before power is turned on. Connecting them to
powered device may cause them not working and may also cause permanent damage to AstroLink device.
1)
USB connection to PC computer can be made after power is switched on without any side effects. When
AstroLink is not powered it will not be recognized by the system.
1) starting from firmware 4.2 it is also possible to connect sensors when power is turned on and sensor is
detected properly
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PROG jumper
In the Revision 2 of AstroLink board there is one jumper that can be set by user. Jumper is labeled PROG
at the board. It is available after opening the case. It can be set to two positions:
·ON. It is default setting. In this setting device is reseted each time USB cable is plugged into USB port
in computer. This setting allows also to reset device remotely with proper setting in the driver. And also
this setting is required for updating AstroLink firmware.
·OFF. In this setting software reset is disabled. Device will not be reseted when USB cable is plugged in
or out to computer or USB hub, remote reset will not work and also updating firmware is not possible.

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Basic operations
AstroLink 4.0 device can be controlled from computer in two modes:
·Direct control. Then AstroLink 4.0 panel connects to device directly and no other software can control
any AstroLink 4.0 functionality
·ASCOM control. In this case AstroLink 4.0 panel connects to device via ASCOM focuser driver. Any
number of other 3rd software can control device in the same time
More details on both solutions can be found in Controlling components chapter.
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First time connect

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To connect AstroLink 4.0 panel software to the device for the first time follow these steps:
·make sure all cables are connected
·turn on power supply. After a few seconds you should hear a double beep
·in AstroLink 4.0 panel select DIRECT connect mode
·click cogwheel settings button next to Connect/Disconnect button
·select proper COM port. Check reset AstroLink device on connect (you can uncheck it later). Click
Test port. Communication should be established
·click Save to close settings window
·click Connect. After a moment panel should communicate to the device and should be fully operational
See controlling components chapter for more information on working with AstroLink 4.0 panel.
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3rd party software
There is also a possibility to useAstroLink panel software together with otherASCOM compatible software
that supports focusing automation (like FocusMax, Sequence Generator Pro or MaxIm DL). In this case you
need to connect AstroLink panel inASCOM connect mode. See Connecting to device section for more
details.
Additionally any other 3rd party software that supports ASCOM relative focuser, ASCOM Switch orASCOM
Observing Conditions can be connected to the device to control and monitor corresponding values. Another
option is to write your own scripts that automates imaging session.
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Board revisions
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Revision 1
Here is the PCB board revision one. In this revision regulated voltage module is mounted upside down, so to
access voltage regulator potentiometer you need to unscrew board and pull it out from the casing.

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Revision 2
Here is the board in revision 2. Changes list:
·regulated voltage module is now oriented correctly, so you can adjust voltage without unscrewing the
board
·PROG jumper has been added
·resettable fuses for motor controllers has been added
·additional PWM filter has been added

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Connecting peripherals
In the following sections details on connecting peripherals to AstroLink device are described.
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Stepper focuser motor
AstroLink device can power both unipolar and bipolar stepper motors. DB9 socket pinout is compatible with
Robofocus and Moonlite focusers.
DB9 socket
pin Robofocuscompatible unipolar stepper motor Bipolar stepper motor
1 Coil A + Coil A +
2 Coil A - Coil A -
3 Coil B+ Coil B+
4 Coil B- Coil B-
5 Common Not connected
6,7,8,9 Not connected Not connected
There is available additional microstepping module that allows to control bipolar steppers with resolution up
to 1/32 step.

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DC focuser motor
DC focuser motor output is compatible with SW Motofocuser. DC motor that you want to connect to RJ9
4pin socket can drain maximum 1.2A current. RJ9 socket connection:
RJ9 pins DC motor connection
1,2 DC motor +
3,4 DC motor -

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Sensors
Two sensors may be connected to the AstroLink 4.0 mini device. One DHT22 temperature/humidity sensor
can be connected to port Sensor 1. To the port Sensor 2 DS1820 temperature sensor can be connected.
Values read from the sensors can be used for:
·controlling PWM output for dewcap heaters (basing on current humidity - DHT22 is required)
·controlling PWM output for temperature regulator (for example for Peltier cooling)
·focuser position temperature compensation
Port Sensor 2 can be also used to connect sky temperature sensor.
Sensors pin-outs and connections are presented in the diagram below. Sensors must be connected to
AstroLink device before power is switched on. Otherwise sensors will not be detected.

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Sensor
pin DHT22 DS1820 Jack plug pin
Vcc (+5V) 1 3 L (tip)
Data 2 2 R (middle)
GND 4 1 C (common)
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Power outputs
There are three switched DC power outputs in the AstroLink mini device. Each of DC power output can
provide up to 5A (however total current drawn from AstroLink mini device cannot exceed 10A). When you
plan your connections please keep in mind power supply considerations presented here.
Voltage at the DC output is equal to the voltage that supplies AstroLink device (can be in a range 11-14V) -
there is no additional voltage regulator in the device for DC outputs.
If you need to switch more than 5A you can use Power switch additional module.
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Regulated PWM outputs
There are two PWM regulated outputs in the AstroLink mini device. Each PWM regulated output can provide
3A of current (however total current drawn from AstroLink mini device cannot exceed 10A). When you plan
your connections please keep in mind power supply considerations presented here .
PWM regulated outputs can work with four different frequencies that can be set in control panel - these are
122, 490, 3900 and 31000 Hz. To minimize voltage ripple it is usually recommended to use higher
frequency, however if PWM receiver cannot for any reason work at high switching frequency, this setting
must be adjusted. Default preset value is 31000Hz.

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Voltage at PWM output is switched from zero to the voltage that AstroLink mini device is supplied (so it can
be in a range 11-14V). There is no additional voltage regulator for PWM outputs.
If you need to switch more than 3A you can use Power switch additional module.
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Regulated voltage output
There is one additional voltage regulator in the AstroLink mini device. This regulator is DC/DC step down
switching regulator that can provide up to 1.5A of continuous current to any customer device (2.5A peak).
This regulated output cannot be turned on and off - it is always on. Voltage at this output can be set using
small potentiometer at switching module (see picture below). Output voltage can be set to any value
between 3V and 10V.
Voltage in the regulator is set to 5 or 8V by default (depending on version). It can be however adjusted by
end client. There is small potentiometer in the DC regulator module. To access it you need to:
·in board Revision 1 - open AstroLink device, unscrew four screws that holds board inside. Then pull it
out and you can access potentiometer in the module
·in board Revision 2 - open AstroLink device and you will see potentiometer in the area next to regulated
voltage output at small separate module (
You will find how to check board revision in How to check versions chapter. You can check how both boards
look like in Board revisions chapter. To adjust voltage you need 2mm flat-blade screwdriver. You can read
mode about regulated voltage output at Regulated voltage application topic.

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Manual control
There is five button remote controller available (sold separately) for AstroLink 4.0 mini device. Controller
needs to be connected to the proper input socket (labeled as Control), and manual control option needs to
be enabled in AstroLink 4 panel software.

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Controlling components
AstroLink 4 mini device functions can be controlled using dedicated software - AstroLink 4 mini panel.
When opened for the first time and connected to the device panel may look like this:
Panel is divided into several sections that are responsible for specific functions control. In the next chapters
each section will be described in details starting from the connection to the device.
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Connecting to device
Panel can communicate with the device in two modes. First one is DIRECT connect - then panel connects
directly to the device and no other interface can control any of device components in the same time. Second
communication mode is ASCOM connect. In this mode panel connects to the device using installed
AstroLink ASCOM Focuser driver, and as this driver is a part of multi-driver Local Server instance many
other applications can control any ofASCOM interfaces in the same time.
DIRECT connect
After selecting DIRECT connect and clicking on Settings button Direct connect settings popup will open.
Then you need to select proper COM port where AstroLink device is connected and detected. After
selecting port you can click Test port to make sure the device is connected properly. After clicking Save
button settings will be saved and software will connect to AstroLink device each time using selected port.
There is another option in the window called reset AstroLink device on connect. When this field is

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checked each time the connection to the device is established AstroLink will reset, so its state will be
restored to the power on state. It can be useful in case when AstroLink is not responding and you work
remotely and cannot switch it off and on. In all other cases it is recommended to keep this field unchecked.
See also PROG jumper chapter.
ASCOM connect (recommended)
After selecting ASCOM connect and clicking on Settings button ASCOM Focuser Chooser window will
open. You need to select AstroLink 4m Focuser interface and then click Propertiesbutton, so ASCOM
connection setup window will open. Here you need to select COM port where AstroLink device is
connected. You can also test connection using Test port button. When trace check-box is checked
ASCOM log file will be written with all communication between device and any software - it can be useful to
investigate errors. Reset AstroLink on connect works in the same way as in DIRECT connect mode.
There is one more setting available forASCOM driver. Under the cogwheel menu in lower left corner there
are Observing Conditions settings. There you can adjust sky temperature cloud coverage mapping points
that corresponds to clear sky and to maximum cloud coverage.
Both connection modes offers the same functionality. The only difference is that DIRECT connect works
exclusively, so no other software than panel can communicate with device. ASCOM connect mode allows
other 3rd party software to operate with device in the same time - see 3rd party software section.
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Focuser control
Once AstroLink panel is connected to the device, stepper focuser motor can be operated with corresponding
controls:

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1. these fields are read only. First field presents current focuser position in steps, second presents focuser
tube position in mm
2. these buttons can be used to relative movement of the focuser. Once '+' or '-' button is pressed focuser
will be moved with the selected number of steps in the desired direction. Minus button moves focuser
inwards (so focuser tube moves into the telescope, and distance between detector and optics
decreases). Plus button moves focuser outwards.Two additional buttons with 'x' prefix allows to coarse
focuser movement. Each time one of these buttons is pressed focuser moves with the selected number
of steps times the selected multiplier. So when relative move field shows 20 steps and you click x4
focuser will move 80 steps. Multiplier can be chosen with value from 2 to 10 (see Coarse move
selection)
3. STOP button can be used to stop focuser movement at any moment
4. Compensate button can be used to compensate focuser position with the steps number displayed in
Compensation amount box. This way we can do compensation in a convenient moment in time, for
example when camera is idle between exposing subframes. You can also reset calculated
compensation amount to zero steps by clicking on the compensation amount window. Confirmation
dialog will appear for this operation. See Temperature compensation section for more details on this
subject. Another option is use script to trigger compensation between subframes - see Temperature
compensation section
5. Settings button. This button opens additional menu with several options:
1. Add position - can be used to store current value in absolute focuser move under selected
name, so it can be restored quickly during the session
2. These are stored positions. After selecting any of them its value will be copied to absolute
focuser move field, and then after button GO is pressed focuser will move to this position. When
you right click on any position you can edit or delete it.
3. Coarse move multiplier selection. Here any value between 2 and 10 can be selected to use for
coarse relative movement
4. Focuser settings button. Clicking here opens Focuser settings window (see below)
6. Absolute focuser move. You can enter any value between 0 and maximum focuser position (see
Settings section) and when you press GO focuser will move to this position
Focuser settings
Settings window contains two tabs. First tab contains stepper motor related settings:
·Max. focuser position - here you need to enter maximum focuser position, so focuser will not move to
any larger value. This is to prevent any mechanical damage to focuser.
·Speed [pps] - focuser stepper speed in pulses per second. You need to select appropriate value, so
focuser will move with reasonable speed, but no steps will be lost during move. For popular unipolar
stepper motors with 7.5 degree step it should be usually no more than 120-150. Bipolar steppers with
1.8 degree step usually can operate with faster rate, up to 400-500pps
·Acceleration [pps/s] - each time stepper starts to move, it accelerates to the speed selected in the field
Speed. Here you can enter acceleration value. So for example, when selected speed is 300pps, and
you select acceleration value for 600, then stepper will accelerate to maximum speed in 0.5 seconds
from move start. This value is also used for manual stepper control, but acceleration is divided by 5 for
this purpose, so it is possible to do small manual corrections.