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Notice: This page contains information for the legacy Phidget21 Library.

Phidget21 is out of support. Bugfixes may be considered on a case by case basis.

Phidget21 does not support VINT Phidgets, or new USB Phidgets released after 2020. We maintain a selection of legacy devices for sale that are supported in Phidget21.

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Click on the 2phidget22.jpg button in the menu bar to go to the Phidget22 version of this page.

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Language - Python: Difference between revisions

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[[Category:Language]]
[[Category:Language]]
[[File:icon-Python.png|64x64px|link=|alt=Python]] Python is an object oriented programming language developed by the [http://www.python.org/psf/summary/ Python Software Foundation], is powerful and easy to learn.
{{OSLang|[[File:icon-Python.png|64x64px|link=|alt=Python]]|Python is an object oriented programming language developed by the [http://www.python.org/psf/summary/ Python Software Foundation], is powerful and easy to learn.}}
 
__TOC__
__TOC__


==Introduction==
==Introduction==


{{LanguageSupport|Python|the complete Phidget API, including events|all Phidget devices.|Windows, Mac OS X and Linux. We provide instructions on how to set up your environment/compilers for [[#Visual Studio 2005/2008/2010 | Visual Studio 2005/2008/2010]], [[#Visual Studio 2003 | Visual Studio 2003]], [[#MonoDevelop | MonoDevelop]] and the [[#Mono | Mono command line compilers]]|}}
{{LanguageSupport|Python|the complete Phidget API, including events|all Phidget devices.|Windows, OS X and Linux. We provide instructions on how to set up your environment for [[#Command line | command line]], [[#IDLE | IDLE]], and [[#Eclipse with PyDev | Eclipse with PyDev]]|
 
Only Python 2.5 or higher is supported (2.6 on Mac).}}


==Quick Downloads==
==Quick Downloads==


Just need the Python documentation, drivers, libraries, and examples?  Here they are:
{{QuickDownloads|Python|
 
{{APIQuickDownloads|{{SERVER}}/documentation/PythonDoc.zip}}
API Documentation:
{{ExtraAPIQuickDownloads|{{SERVER}}/documentation/web/PythonDoc/Phidgets.html|HTML Version of}}|
*[http://www.phidgets.com/documentation/PythonDoc.zip API Manual]
{{ExampleQuickDownloads|{{SERVER}}/downloads/phidget21/examples/python/Python.zip|}}|
 
{{ExtraLibraryQuickDownloads|{{SERVER}}/downloads/phidget21/libraries/any/PhidgetsPython.zip|Python|}}
Example Code:
{{WindowsQuickDownloads}}
 
{{MacQuickDownloads}}
*[http://www.phidgets.com/downloads/examples/Python_2.1.8.20120131.zip Example Code]
{{LinuxQuickDownloads}}
 
}}
Libraries and Drivers:
*[http://www.phidgets.com/downloads/libraries/PhidgetsPython_2.1.8.20120131.zip Python Library]
*[http://www.phidgets.com/downloads/libraries/Phidget-x86_2.1.8.20111220.exe 32-bit Windows Drivers Installer]
*[http://www.phidgets.com/downloads/libraries/Phidget-x64_2.1.8.20111220.exe 64-bit Windows Drivers Installer]
*[http://www.phidgets.com/downloads/libraries/libphidget_2.1.8.20111028.tar.gz Linux Source]
*[http://www.phidgets.com/downloads/libraries/Phidget_2.1.8.20111103.dmg General Mac OS X Drivers Installer]


==Getting started with Python==
==Getting started with Python==
Line 33: Line 28:
Instructions are divided up by operating system. Choose:
Instructions are divided up by operating system. Choose:
*[[#Windows(2000/XP/Vista/7)|Windows 2000 / XP / Vista / 7]]
*[[#Windows(2000/XP/Vista/7)|Windows 2000 / XP / Vista / 7]]
*[[#Mac OS X |Mac OS X]]
*[[#OS X |OS X]]
*[[#Linux | Linux]] (including PhidgetSBC)
*[[#Linux | Linux]] (including PhidgetSBC)


==Windows(2000/XP/Vista/7)==
==Windows (XP/Vista/7/8)==


===Description of Library===
===Description of Library===
C# programs on Windows depend on the following files, which the installers above put onto your system:
Python programs on Windows depend on the following. The installers in the [[#Libraries and Drivers | Quick Downloads]] section put only the {{Code|phidget21.dll}} into your system. You will need to manually put the Phidget Python Module into your system.
* <b>{{Code|phidget21.dll}}</b> contains the actual Phidgets library, which is used at run-time.  By default, it is placed in {{Code|C:\Windows\System32}}.
* <b>{{Code|phidget21.dll}}</b> contains the actual Phidget library, which is used at run-time.  By default, it is placed in {{Code|C:\Windows\System32}}.
You will also need one of the following two files, depending on the .NET framework version you are targeting:
* <b>{{Code|Phidget Python Module}}</b> is the Phidget library for Python.
* <b>{{Code|Phidgets Python Module}}</b> is the Phidgets library for Python <i><b>2.5</b></i> or higher. Your compiler has to know where this file is.  
* <b>{{Code|setup.py}}</b> is used to install the Phidget module into the standard location for third party Python modules. On typical Python environments, this setup will install the Phidget Python module in the {{Code|site-packages}} directory.  


If you do not want to use our installer, you can download the five [http://www.phidgets.com/downloads/libraries/Phidget21-windevel_2.1.8.20111220.zip file files].
If you do not want to use our installer, you can download the [{{SERVER}}/downloads/phidget21/libraries/windows/Phidget21-windevel.zip {{Code|phidget21.dll}}] and refer to our [[OS - Windows|Windows page]] for manual installation instructions.


The first thing you will have to do is to [[#Installing the Phidget Python Module |install the {{Code|Phidget Python Module}}]].
Afterwards, Running the examples and writing your own code can be fairly compiler-specific, so we include instructions for each environment below.


Running the examples and writing your own code can be fairly compiler-specific, so we include instructions for each compiler below.
===Installing the Phidget Python Module===
 
Please start by downloading [{{SERVER}}/downloads/phidget21/libraries/any/PhidgetsPython.zip Phidget Python Module]. After extracting the file, open up a command line terminal, traverse to the directory containing {{Code|setup.py}} and enter the following to install the Phidget Python module into the Python environment.
 
<div class="source">
<syntaxhighlight lang=bash>
python setup.py install
</syntaxhighlight>
</div>
 
===Command Line===
 
====Use Our Examples====
Please ensure that the Phidget Python Module is [[#Installing the Phidget Python Module | installed]] onto your system.
 
Next, download the [{{SERVER}}/downloads/phidget21/examples/python/Python.zip examples] and unpack them into a folder.  While these examples were written in Python 3.0, they are also compatible with Python 2.5 (with a [[#Common_Problems_and_Solutions.2FWorkarounds | minor modification]]). It is probably best to start with the HelloWorld program, which will work with any Phidget.  There is also an example file for your specific Phidget device.  {{FindYourDevice}}
 
Now, open up a command line prompt and navigate to the directory of the example folder.
 
Next, enter the following to run the example:
 
<div class="source">
<syntaxhighlight lang=bash>
python example.py
</syntaxhighlight>
</div>
 
Once you have the Python examples running, we have a [[#Follow the Examples|teaching]] section below to help you follow them.
 
====Write Your Own Code====
 
When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidgets Python libraries. Please see the [[#Use Our Examples| Use Our Examples ]] section for instructions.
 
Then, in your code, you will need to reference to the Phidget Python library.
 
<div class="source">
<syntaxhighlight lang=python>
from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *
</syntaxhighlight>
</div>
 
Then, you will also have to add a reference to your particular Phidget.  For example, you would include the following line for a PhidgetInterfaceKit:
<div class="source">
<syntaxhighlight lang=python>
from Phidgets.Devices.InterfaceKit import *
</syntaxhighlight>
</div>
 
Please see the [{{SERVER}}/downloads/phidget21/examples/python/Python.zip examples] on how to add a reference to your particular Phidget.
 
The project now has access to the Phidget function calls and you are ready to begin coding.
 
The same [[#Follow the Examples|teaching ]] section which describes the examples also has further resources for programming your Phidget.


===IDLE===
===IDLE===


=====Use Our Examples=====
====Use Our Examples====


Please start by downloading the [http://www.phidgets.com/downloads/examples/Python_2.1.8.20120131.zip examples] and unpack them into a foler.  While these examples were written in Python 3.0, they are also compatible with Python and 2.5 and 2.6.
Please ensure that the Phidget Python Module is [[#Installing the Phidget Python Module | installed]] onto your system.  


If you aren't sure what the software example for your device is called, check the software object listed in the [[Device List | Getting Started guide for your device]]. Open the example in the IDLE editor
Next, download the [{{SERVER}}/downloads/phidget21/examples/python/Python.zip examples] and unpack them into a folder.  While these examples were written in Python 3.0, they are also compatible with Python 2.5 (with a [[#Common_Problems_and_Solutions.2FWorkarounds | minor modification]]). It is probably best to start with the HelloWorld program, which will work with any Phidget.  There is also an example file for your specific Phidget device. {{FindYourDevice}}  Now, open the example in the IDLE editor.


The only thing left to do is to run the examples! Click on Run &rarr; Run Module
The only thing left to do is to run the examples! Click on Run &rarr; Run Module.


[[File:Python IDLE Run.PNG|link=|alt=Run‎]]
[[File:Python IDLE Run.PNG|link=|alt=Run?]]


Once you have the Python examples running, we have a [[#Follow The Examples|teaching]] section below to help you follow them.
Once you have the Python examples running, we have a [[#Follow the Examples|teaching]] section below to help you follow them.


=====Write Your Own Code=====
====Write Your Own Code====


When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidget C# libraries. To begin:
When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidget Python library. Please see the [[#Use Our Examples 2| Use Our Examples ]] section for instructions.


1. Generate a new Visual C# Windows Applications project with a descriptive name such as PhidgetTest.  
Then, in your code, you will need to reference to the Phidget Python library.


[[File:CSharp VS2005 New Project.PNG|link=|alt=New Project]]
<div class="source">
<syntaxhighlight lang=python>
from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *
</syntaxhighlight>
</div>
 
Then, you will also have to add a reference to your particular Phidget.  For example, you would include the following line for a PhidgetInterfaceKit:
<div class="source">
<syntaxhighlight lang=python>
from Phidgets.Devices.InterfaceKit import *
</syntaxhighlight>
</div>
 
Please see the [{{SERVER}}/downloads/phidget21/examples/python/Python.zip examples] on how to add a reference to your particular Phidget.
 
The project now has access to the Phidget function calls and you are ready to begin coding.
 
The same [[#Follow the Examples|teaching ]] section which describes the examples also has further resources for programming your Phidget.
 
===Eclipse with PyDev===
 
====Use Our Examples====
 
1. Please ensure that the Phidget Python Module is [[#Installing the Phidget Python Module | installed]] onto your system.
 
2. Next, download the [{{SERVER}}/downloads/phidget21/examples/python/Python.zip examples] and unpack them into a folder.  While these examples were written in Python 3.0, they are also compatible with Python 2.5 (with a [[#Common_Problems_and_Solutions.2FWorkarounds | minor modification]]). It is probably best to start with the HelloWorld program, which will work with any Phidget.  There is also an example file for your specific Phidget device.  {{FindYourDevice}}  You will need this example source code to be imported into your project later on.
 
3. Next, a new project will need to be created. Generate a new PyDev project with a descriptive name such as PhidgetTest.
 
[[File:Python PyDev New Project.PNG|link=|alt=New Project]]
 
4. To import the example program into your project, right click the Project and select {{Code|Import}}.
 
[[File:Python PyDev Import File 1.PNG|link=|alt=Import File]]
 
5. On the next screen, select {{Code|File System}} and proceed to the next screen.


2. Add a reference to the .NET Phidgets library.
[[File:Python PyDev Import File 2.PNG|link=|alt=Import File]]


[[File:CSharp VS2005 Add Reference.PNG|link=|alt=Add Reference]]
6. Browse to the directory where you extracted the examples into, and select the example you wish to open.


3. Under the .NET tab, select {{Code|Phidget21.NET.dll}}.
[[File:Python PyDev Import File 3.PNG|link=|alt=Import File]]
If you used our installer, these files are installed in {{Code|C:\Program Files\Phidgets}}, by default. If it does not appear in this list, then you can browse to the Phidget Framework installation directory and add the file.


[[File:CSharp VS2005 Add Reference 2.PNG|link=|alt=Add Reference]]
7. The only thing left to do is to run the examples! Click on Run &rarr; Run.


4. Then, in your code, you will need to include the Phidget library:
[[File:Python PyDev Run.PNG|link=|alt=Run?]]
 
Once you have the Python examples running, we have a [[#Follow the Examples|teaching]] section below to help you follow them.
 
====Write Your Own Code====
 
When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidget Python library. Please see the [[#Use Our Examples 3 | Use Our Examples ]] section for instructions.
 
Then, in your code, you will need to include a reference to the Phidget Python library.


<div class="source">
<div class="source">
<syntaxhighlight lang=csharp>
<syntaxhighlight lang=python>
  using Phidgets;
from Phidgets.PhidgetException import *
  using Phidgets.Events;
from Phidgets.Events.Events import *
</syntaxhighlight>
</syntaxhighlight>
</div>
</div>


You will also have to add a reference to your particular Phidget.  For example, you would include the following line for a PhidgetInterfaceKit:
<div class="source">
<syntaxhighlight lang=python>
from Phidgets.Devices.InterfaceKit import *
</syntaxhighlight>
</div>


The project now has access to the Phidget21 function calls and you are ready to begin coding.
Please see the [{{SERVER}}/downloads/phidget21/examples/python/Python.zip examples] on how to add a reference to your particular Phidget.


The same [[#Follow The Examples|teaching ]] section which describes the examples also has further resources for programming your Phidget.
The project now has access to the Phidget function calls and you are ready to begin coding.


===Visual Studio 2003===
The same [[#Follow the Examples|teaching ]] section which describes the examples also has further resources for programming your Phidget.


=====Use Our Examples=====
==OS X==


1. Download the [http://www.phidgets.com/downloads/examples/CSharp_2.1.8.20110615.zip examples] and unpack them into a folder. Here, you can find example programs for all the devices. If you are not sure what the software example for your device is called, check the software object listed in the [[Device List | Getting Started guide for your device]]. As the examples were written in newer versions of Visual Studio, Visual Studio 2003 is not able to open the examples. Fortunately, you can import the simple examples to a Visual Studio 2003 project. It will be difficult to import the full examples as you will need to recreate the GUI components. In the [[#Use Our Examples 2 | Use Our Examples]] section, it will be assumed that the simple examples are used. You will need this example source code to be copied into your C# project later on.  
The first step in using Python on Mac is to install the Phidget libraries. Compile and install them as explained on the [[OS - OS X]] page, which also describes the different Phidget files, their installed locations, and their roles....


2. Next, a new project will need to be created. Generate a new Visual C# console application project with a descriptive name such as PhidgetTest.
The next step is to install the Phidget Python module. Download it here:
* [{{SERVER}}/downloads/phidget21/libraries/any/PhidgetsPython.zip Phidget Python Module]


[[File:CSharp_VS2003 New Project.PNG|link=|alt=New Project]]
Then, unpack the module and enter the root of the newly unzipped directory. There will be a script in the base directory called {{Code|setup.py}}.  This is used the same way as most other distributed Python modules - from a command line type:


3. Add a reference to the .NET Phidgets library.
<div class="source">
<syntaxhighlight lang=bash>
python setup.py install
</syntaxhighlight>
</div>


[[File:CSharp_VS2003 Add Reference 1.PNG|link=|alt=Add Reference]]
This will build the module and install the built python module files into your {{Code|site-packages}} directory.


4. Under the .NET tab, select {{Code|Phidget21.NET1.1.dll}}. If you used our installer, by default, this file is placed in {{Code|C:\Program Files\Phidgets}}. If it is in another location, please change the path to the file's location accordingly.
===Use Our Examples===


[[File:CSharp_VS2003 Add Reference 2.PNG|link=|alt=Add Reference]]
First, download the examples:
*[{{SERVER}}/downloads/phidget21/examples/python/Python.zip Phidget Python Examples]


5. To import the simple example program into your project, please: open up {{Code|Class1.cs}}.
Unpack them, and enter the root directory.  You will find examples specific to each Phidget device, as well as a {{Code|HelloWorld.py}} example.  The {{Code|HelloWorld.py}} code is probably the easiest example to run as it will work with any Phidget device.  Or you can use the example specific to your Phidget. {{FindYourDevice}}


6. Traverse to the example in Windows Explorer and locate the {{Code|Program.cs}} file.
The Phidget examples were written in Python 3.0 and this tutorial assumes its use. However, they should still be compatible with Python 2.6. To run the examples using Python 2.5, you will need to modify the example code in the exception handling to read “except RuntimeError, e:”, instead of “except RuntimeError as e:”.


[[File:CSharp VS2003 Source Code.PNG|link=|alt=Source Code]]
If needed, make those changes to the {{Code|HelloWorld.py}} example or the one for your Phidget. 


7. Copy and paste the contents from that file into {{Code|Class1.cs}}.
8. Comment out the following line as it is not supported in .NET 1.1:
<div class="source">
<div class="source">
<syntaxhighlight lang=csharp>
<syntaxhighlight lang=bash>
  using System.Collections.Generic;
python HelloWorld.py
</syntaxhighlight>
</syntaxhighlight>
</div>
</div>


[[File:CSharp VS2003 Source Code 2.PNG|link=|alt=Source Code]]
===Write Your Own Code===
 
When writing your code from scratch, you start it as you would any Python code, such as within a text editor like Emacs, Vi, Gedit, or Kate.  In your '''{{Code|.py}}''' source code file, you must include a reference to the Phidget module:


9. Then, in your code, you will need to include the Phidget library:
<div class="source">
<div class="source">
<syntaxhighlight lang=csharp>
<syntaxhighlight lang=python>
  using Phidgets;
from Phidgets.PhidgetException import *
  using Phidgets.Events;
from Phidgets.Events.Events import *
</syntaxhighlight>
</syntaxhighlight>
</div>
</div>


10. Now, you can run the example. Click on Debug &rarr; Start.
In addition, you should include the module functions for your specific device. In the case of the Interface Kit, this would be:


[[File:CSharp VS2003 Run.PNG|link=|alt=Run]]
<div class="source">
<syntaxhighlight lang=python>
from Phidgets.Devices.InterfaceKit import *
</syntaxhighlight>
</div>


Once you have the C# examples running, we have a [[#Follow The Examples|teaching ]] section below to help you follow them.
For other devices, it would be the software object you found when running the examples above.  Then, you would run your Python code the same way as the examples.


=====Write Your Own Code=====
To learn how to write your own code for your Phidget, and to learn more about our API, we have a [[#Follow the Examples|teaching]] section to help you follow the provided Python examples and which has resources such as the API reference.


When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your development environment to properly link the Phidget C# libraries. Please see the [[#Use Our Examples 2 | Use Our Examples ]] section for instructions.
==Linux==


===Mono===
Python has excellent support on Linux. 


This section will provide instructions on how to compile using the {{Code|mcs}} compiler. Other compilers such as {{Code|gmcs}}, {{Code|smcs}}, and {{Code|dmcs}} all work in the same way. Start by downloading the C# Examples.  
The first step in using Python on Linux is to install the Phidget libraries.  These are the core Phidget libraries, written in C, which when compiled become part of the programming libraries available to your system. Download, compile, and install from the links and instructions on the main [[OS - Linux | Linux page]]. That Linux page also describes the different Phidget files, their installed locations, and their roles.


=====Use Our Examples=====
The next step is to install the Phidget Python module.  Download it here:
* [{{SERVER}}/downloads/phidget21/libraries/any/PhidgetsPython.zip Phidget Python Module]


Download the [http://www.phidgets.com/downloads/examples/CSharp_2.1.8.20110615.zip examples] and unpack them into a folder. Here, you can find example programs for all the devices. If you aren't sure what the software example for your device is called, check the software object listed in the [[Device List | Getting Started guide for your device]]. Please only use the simple examples. The full examples uses Windows Forms, which Mono and the Gtk# toolkit are not completely compatible with. Locate the {{Code|Program.cs}} file as this contains the example source code. Copy the file into your working directory, and rename it to {{Code|example.cs}}.
Then, unpack the module and enter the root of the newly unzipped directory. There will be a script in the base directory called {{Code|setup.py}}. This is used the same way as most other distributed Python modules - from a command line type:
<br/>


To compile and build an executable, run:
<div class="source">
<div class="source">
<syntaxhighlight lang=bash>
<syntaxhighlight lang=bash>
mcs /out:example.exe /lib:"C:\Program Files\Phidgets" /r:phidget21.NET.dll example.cs
python setup.py install
</syntaxhighlight>
</syntaxhighlight>
</div>
</div>


If you have the {{Code|Phidget21.NET.dll}} installed in another location, please change the path to the file's location accordingly.
This will build the module and install the built python module files into your {{Code|site-packages}} directory.
 
===Use Our Examples===
 
First, download the examples:
*[{{SERVER}}/downloads/phidget21/examples/python/Python.zip Phidget Python Examples]
 
Unpack them, and enter the root directory.  You will find examples specific to each Phidget device, as well as a {{Code|HelloWorld.py}} example.  The {{Code|HelloWorld.py}} code is probably the easiest example to run as it will work with any Phidget device.  Or you can use the example specific to your Phidget.  {{FindYourDevice}}
 
The Phidget examples were written in Python 3.0 and this tutorial assumes its use. However, they should still be compatible with Python 2.6. To run the examples using Python 2.5, you will need to modify the example code in the exception handling to read “except RuntimeError, e:”, instead of “except RuntimeError as e:”.
 
If needed, make those changes to the {{Code|HelloWorld.py}} example or the one for your Phidget. 
 
Then, if you have not set up [[OS_-_Linux#Setting_udev_Rules|your udev rules for USB access]], you will need to run the Python example as '''root''':


Afterwards, you will have an executable named {{Code|example.exe}} that you can run. Place the {{Code|Phidget21.NET.dll}} in the same directory as the executable and type the following to run the program:
<div class="source">
<div class="source">
<syntaxhighlight lang=bash>
<syntaxhighlight lang=bash>
mono example.exe
sudo python HelloWorld.py
</syntaxhighlight>
</syntaxhighlight>
</div>
</div>


Once you have the C# examples running, we have a [[#Follow The Examples|teaching]] section below to help you follow them.
===Write Your Own Code===


=====Write Your Own Code=====
When writing your code from scratch, you start it as you would any Python code on Linux, such as within a text editor like Emacs, Vi, Gedit, or Kate.  In your '''{{Code|.py}}''' source code file, you must include a reference to the Phidget module:


When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your development environment to properly link the Phidget C# libraries. Please see the [[#Use Our Examples 3 | Use Our Example ]] section for instructions.
<div class="source">
<syntaxhighlight lang=python>
from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *
</syntaxhighlight>
</div>


In your code, you will need to include the Phidget library:
In addition, you should include the module functions for your specific device.  In the case of the Interface Kit, this would be:


<div class="source">
<div class="source">
<syntaxhighlight lang=csharp>
<syntaxhighlight lang=python>
  using Phidgets;
from Phidgets.Devices.InterfaceKit import *
  using Phidgets.Events;
</syntaxhighlight>
</syntaxhighlight>
</div>
</div>


For other devices, it would be the software object you found when running the examples above.  Then, you would run your Python code the same way as the examples.


The project now has access to the Phidget21 function calls and you are ready to begin coding.
To learn how to write your own code for your Phidget, and to learn more about our API, we have a [[#Follow the Examples|teaching]] section to help you follow the provided Python examples and which has resources such as the API reference.


The same [[#Follow The Examples|teaching]] section which describes the examples also has further resources for programming your Phidget.
==Follow the Examples==


===MonoDevelop===
By following the instructions for your operating system and compiler above, you probably now have a working example and want to understand it better so you can change it to do what you want.  This teaching section has resources for you to learn from the examples and write your own.


=====Use Our Examples=====
Your main reference for writing Python code will be our Python API information, with syntax for all of our functions:


Download the [http://www.phidgets.com/downloads/examples/CSharp_2.1.8.20110615.zip examples] and unpack them into a folder. Here, you can find example programs for all the devices. These examples were written in Visual Studio 2005 and 2008, but are also compatible with MonoDevelop.
{{UsingAPhidgetInCodeGeneral|both of which are available in Python|[{{SERVER}}/documentation/PythonDoc.zip Python API]}}


To load all projects in MonoDevelop, go to File &rarr; Open, and open {{Code|AllExamples/AllExamples.sln}}
===Example Flow===


This will load all of the examples available for C#, and then you can set your main project to be the one that matches your deviceIf you aren't sure what the software example for your device is called, check the software object listed in the [[Device List | Getting Started guide for your device]]. If you are running under the .NET framework, you can use either the full or simple examples. Otherwise, if you are running under the Mono framework, please only use the simple examples. The full examples uses Windows Forms, which is not completely compatible with Mono's Gtk#.
{{ExamplePseudocode|In Python, you can name these '''event''' functions whatever you like.  You will then pass their function names to the Phidget library below in the Main Code sectionThis hooks them into the actual events when they occur. <br>
In the example code, the event functions common to all Phidgets are called things like '''AttachHandler()''' and '''DetachHandler()''', etc.<br><br>
Some event functions will be specific to each device, like when a tag is read on an RFID board, or when a sensor value changes on an Interface Kit.
Other functions are given in the examples to show you more detail on using your Phidget.  For example, '''DeviceInitialize()''' will show what needs to be set up for your Phidget before using it.
|Creating a Phidget software object in Python is specific to the Phidget. For a Phidget Spatial, for example, this would involve creating a {{Code|Spatial}} object.  The examples show how to do this and other API functions.<br><br>
The object provides device specific methods and properties which are available from the API for your specific Phidget.|
[{{SERVER}}/documentation/PythonDoc.zip Python API]}}


[[File:CSharp MonoDevelop Win Start Up.PNG|link=|alt=Start Up Project]]
===Code Snippets===


The only thing left to do is to run the examples! Right click the project, and click on {{Code|Run With}} and select the target framework. Please note that the projects, by default try to find the {{Code|Phidget21.NET.dll}} in the {{Code|C\Program Files\Phidgets}}. If you have it installed in another location, please change the path to the file's location accordingly. If you are receiving an error message regarding that the namespace Phidgets cannot be found, please re-add the reference to {{Code|Phidget21.NET.dll}}. Please see the [[#Write Your Own Code 4 | Write Your Own Code]] section for details.  
Specific calls in Python will differ in syntax from those on the [[General Phidget Programming]] page, but the concepts stay the same.


[[File:CSharp MonoDevelop Win Run As.PNG|link=|alt=Run As]]
It may help to have the [[General Phidget Programming]] page and this section open at the same time, because they parallel each other and you can refer to the Python syntax.  However, many additional concepts are covered on the General Phidget Programming page on a high level, such as using multiple Phidgets, handling errors, and different styles of programming.


Once you have the C# examples running, we have a [[#Follow The Examples|teaching]] section below to help you follow them.
For example, if we were using a [{{SERVER}}/products.php?product_id=1018 Phidget Interface Kit] as our device, the general calls would look like this:


=====Write Your Own Code=====
====Step One: Initialize and Open====


When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your  development environment to properly link the Phidget C# libraries. To begin:
<div class="source">
<syntaxhighlight lang=python>
# Create
try:
  device = InterfaceKit()
except RuntimeError as e:
  print("Runtime Error: %s" % e.message)


1. Create a new C# empty project with a descriptive name such as PhidgetTest.
# Open
try:
  device.openPhidget()
except PhidgetException as e:
  print (“Phidget Exception %i: %s” % (e.code, e.detail))
  exit(1)
</syntaxhighlight>
</div>


[[File:CSharp MonoDevelop Win New Project.PNG|link=|alt=New Project]]
The variable {{Code|device}} is now a handle for the Phidget.  This example is ''specific to the Interface Kit'' because the call InterfaceKit() is used.  For another device, use the correspondingly named call in the Python API.  


2. Add a reference to the .NET library.  
The handle '''device''' is then used for all the Python function calls using the Phidget for its device-specific functions - in this case, Interface Kit specific functions. Every type of Phidget also inherits functionality from the Phidget base class.


[[File:CSharp MonoDevelop Win Reference.PNG|link=|alt=Add Reference]]
Note that open() opens the software object, but not hardware.  So, it is not a guarantee you can use the Phidget immediately.  The different types of open can be used with parameters to try and get the first device it can find, open based on its serial number, or even open across the network. The API manual lists all of the available modes that open provides.


3. Select {{Code|Phidget21.NET.dll}}. If you used our installer, by default, this file is placed in {{Code|C:\Program Files\Phidgets}}. If it is in another location, please change the path to the file's location accordingly.
Also note that you can catch exceptions thrown by the Phidget library as we did above when using the openPhidget() call.  In other words, this should probably be present around most of your Phidget calls, especially when you are learning how to use the Phidget and debugging your code:


[[File:CSharp MonoDevelop Win Reference 2.PNG|link=|alt=Add Reference]]
<div class="source">
<syntaxhighlight lang=python>
try:
  # Your code goes here
except PhidgetException as e:
  print (“Phidget Exception %i: %s” % (e.code, e.detail))
  exit(1)
</syntaxhighlight>
</div>
 
====Step Two: Wait for Attachment (plugging in) of the Phidget====
 
To use the Phidget, it must be plugged in (attached).  We can handle this simply by calling waitForAttachment. This function works for any Phidget. WaitForAttachment will block indefinitely until a connection is made to the Phidget, or an optional timeout is exceeded:
 
<div class="source">
<syntaxhighlight lang=python>
device.waitForAttach(10000)
print ("%d attached!" % (device.getSerialNum()))
</syntaxhighlight>
</div>


4. Then, in your code, you will need to include the Phidget library:
Sometimes, it makes more sense to handle the attachment via an event. This would be in instances where the Phidget is being plugged and unplugged, and you want to handle these incidents.  Or, when you want to use event-driven programming because you have a GUI-driven program.  In these cases, an event-driven code snippet to handle the attachment might look something like this:


<div class="source">
<div class="source">
<syntaxhighlight lang=csharp>
<syntaxhighlight lang=python>
  using Phidgets;
def AttachHandler(event):
  using Phidgets.Events;
    attachedDevice = event.device
    serialNumber = attachedDevice.getSerialNum()
    deviceName = attachedDevice.getDeviceName()
    print("Hello to Device " + str(deviceName) + ", Serial Number: " + str(serialNumber))
 
# Insert code for -creating- device here....
 
try:
    device.setOnAttachHandler(AttachHandler)
except PhidgetException as e:
    # Insert code for handling any exceptions
    # A common exception will occur if you do not create the device properly above
 
# Insert code for -opening- device here....
</syntaxhighlight>
</syntaxhighlight>
</div>
</div>


The project now has access to the Phidget21 function calls and you are ready to begin coding.
====Step Three: Do Things with the Phidget====


The same [[#Follow The Examples|teaching]] section which describes the examples also has further resources for programming your Phidget.
You can read data and interact with your Phidget both by polling it for its current state (or to set a state), or by catching events that trigger when the data changes.


==Mac OS X==
For our [{{SERVER}}/products.php?product_id=1018 | Phidget Interface Kit], the polling method of getting the current sensor state and setting an output state looks something like this:


Python has excellent support on Mac OS X.
<div class="source">
<syntaxhighlight lang=python>


The first step in using Python on Mac is to install the Phidget libraries.  Compile and install them as explained on the [[Device List|getting started guide for your device]].  Then, the [[OS - Mac OS X]] page also describes the different Phidget files, their installed locations, and their roles....
# Get a data point from Analog Port 0
device.getSensorValue(0)


==Linux==
# Set digital output port 0 to be on
device.setOutputState(0, 1)
 
</syntaxhighlight>
</div>
 
To catch data changes via events, you would use something like this:
 
<div class="source">
<syntaxhighlight lang=python>
 
def sensorChanged(e):
  print (“Sensor %i: %i” % (e.index, e.value))
  return 0
 
# Insert code to create an Interface Kit called 'device'
 
# Hook our function above into the device object
device.setOnSensorChangeHandler(sensorChanged)


Python has support on Linux. 
# Insert code to open 'device'


The first step in using Python on Linux is to install the Phidget libraries.  Compile and install them as explained on the main [[OS - Linux | Linux page]].  That Linux page also describes the different Phidget files, their installed locations, and their roles.
</syntaxhighlight>
</div>


==Follow The Examples==
====Step Four: Close and Delete====


By following the instructions for your operating system and compiler above, you probably now have a working example and want to understand it better so you can change it to do what you want.  This teaching section has resources for you to learn from the examples and write your own.
At the end of your program, don’t forget to call closePhidget() to free any locks on the Phidget that the openPhidget() call put in place!


Next, comes our API information.  These resources outline the Python Phidget functions:
<div class="source">
<syntaxhighlight lang=python>


{{UsingAPhidgetInCodeGeneral|both of which are available in Python|[http://www.phidgets.com/documentation/PythonDoc.zip Python API]}}
device.closePhidget()


===Example Flow===
</syntaxhighlight>
</div>


{{ExamplePseudocode|In Python, you can name these '''event''' functions whatever you like.  You will then pass them as function pointers to the Phidget library below in the Main Code section.  This hooks them into the actual events when they occur. <br>
{{MoreHowTos}}
In the example code, the event functions common to all Phidgets are called things like '''AttachHandler()''' and '''DetachHandler()''', etc.<br><br>
Some event functions will be specific to each device, like when a tag is read on an RFID board, or when a sensor value changes on an Interface Kit.
Other functions are given in the examples to show you more detail on using your Phidget.  For example, '''DeviceInitialize()''' will show what needs to be set up for your Phidget before using it.
|Creating a Phidget software object in Python is specific to the Phidget.  For a Phidget Spatial, for example, this would involve creating a {{Code|Spatial}} object.  The examples show how to do this and other API functions.<br><br>
The object provides device specific methods and properties which are available from the API for your specific Phidget.|
[http://www.phidgets.com/documentation/PythonDoc.zip Python API]}}


==Code Snippets==
The ''complete'' set of functions you have available for all Phidgets can be found in the [{{SERVER}}/documentation/PythonDoc.zip Python API]. You can also find more description on any device-specific function in the Device API page for your specific Phidget, which can be found in its [[:Category:UserGuide|user guide]].


==Common Problems and Solutions/Workarounds==
==Common Problems and Solutions/Workarounds==


Here you can put various frequent problems and our recommended solutions.
==={{ProblemSolution|OS X|My application hangs when using multiple devices in a single Python application.}}===
 
A call to {{Code|open}} may hang indefinitely if multiple devices are being programmed in a single Python application. To circumvent this, allow the application to delay a short period between {{Code|open}} calls. For most environments, a 1.25 millisecond delay is enough. For example:
<div class="source">
<syntaxhighlight lang=python>
import time
...
interface_kit.openPhidget(94695)
time.sleep(0.00125)
rfid.openPhidget(33502)
</syntaxhighlight>
</div>
 
 
==={{ProblemSolution|All Operating Systems|The examples produce an error while running in a Python 2.5 environment.}}===
 
Running the examples produces an error similar to the following:
<div class="source">
<syntaxhighlight lang=python>
InterfaceKit-simple.py:33: Warning: 'as' will become a reserved keyword in Python 2.6
  File "InterfaceKit-simple.py", line 33
    except RuntimeError as e:
SyntaxError: invalid syntax
</syntaxhighlight>
</div>
 
To run the example code in Python 2.5, all the lines containing:
<div class="source">
<syntaxhighlight lang=python>
except RuntimeError as e:
</syntaxhighlight>
</div>
will need to be replaced with:
<div class="source">
<syntaxhighlight lang=python>
except Runtime, e:
</syntaxhighlight>
</div>
 
And then it should run.

Latest revision as of 14:21, 7 June 2017

Python Python is an object oriented programming language developed by the Python Software Foundation, is powerful and easy to learn.

Introduction

If this is your first time working with a Phidget, we suggest starting with the Getting Started page for your specific device. This can be found in the user guide for your device. That page will walk you through installing drivers and libraries for your operating system, and will then bring you back here to use Python specifically.

Python is capable of using the complete Phidget API, including events. We also provide example code in Python for all Phidget devices.

Python can be developed with Windows, OS X and Linux. We provide instructions on how to set up your environment for command line, IDLE, and Eclipse with PyDev.

Only Python 2.5 or higher is supported (2.6 on Mac).

You can compare Python with our other supported languages.

Quick Downloads

Just need the Python documentation, drivers, libraries, and examples? Here they are:

Documentation

Example Code

Libraries and Drivers


Getting started with Python

If you are new to writing code for Phidgets, we recommend starting by running, then modifying existing examples. This will allow you to:

  • Make sure your libraries are properly linked
  • Go from source code to a test application as quickly as possible
  • Ensure your Phidget is hooked up properly

Instructions are divided up by operating system. Choose:

Windows (XP/Vista/7/8)

Description of Library

Python programs on Windows depend on the following. The installers in the Quick Downloads section put only the phidget21.dll into your system. You will need to manually put the Phidget Python Module into your system.

  • phidget21.dll contains the actual Phidget library, which is used at run-time. By default, it is placed in C:\Windows\System32.
  • Phidget Python Module is the Phidget library for Python.
  • setup.py is used to install the Phidget module into the standard location for third party Python modules. On typical Python environments, this setup will install the Phidget Python module in the site-packages directory.

If you do not want to use our installer, you can download the phidget21.dll and refer to our Windows page for manual installation instructions.

The first thing you will have to do is to install the Phidget Python Module. Afterwards, Running the examples and writing your own code can be fairly compiler-specific, so we include instructions for each environment below.

Installing the Phidget Python Module

Please start by downloading Phidget Python Module. After extracting the file, open up a command line terminal, traverse to the directory containing setup.py and enter the following to install the Phidget Python module into the Python environment.

python setup.py install

Command Line

Use Our Examples

Please ensure that the Phidget Python Module is installed onto your system.

Next, download the examples and unpack them into a folder. While these examples were written in Python 3.0, they are also compatible with Python 2.5 (with a minor modification). It is probably best to start with the HelloWorld program, which will work with any Phidget. There is also an example file for your specific Phidget device. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our webpage, and then check the API documentation for it.

Now, open up a command line prompt and navigate to the directory of the example folder.

Next, enter the following to run the example:

python example.py

Once you have the Python examples running, we have a teaching section below to help you follow them.

Write Your Own Code

When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidgets Python libraries. Please see the Use Our Examples section for instructions.

Then, in your code, you will need to reference to the Phidget Python library.

from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a PhidgetInterfaceKit:

from Phidgets.Devices.InterfaceKit import *

Please see the examples on how to add a reference to your particular Phidget.

The project now has access to the Phidget function calls and you are ready to begin coding.

The same teaching section which describes the examples also has further resources for programming your Phidget.

IDLE

Use Our Examples

Please ensure that the Phidget Python Module is installed onto your system.

Next, download the examples and unpack them into a folder. While these examples were written in Python 3.0, they are also compatible with Python 2.5 (with a minor modification). It is probably best to start with the HelloWorld program, which will work with any Phidget. There is also an example file for your specific Phidget device. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our webpage, and then check the API documentation for it. Now, open the example in the IDLE editor.

The only thing left to do is to run the examples! Click on Run → Run Module.

Run?

Once you have the Python examples running, we have a teaching section below to help you follow them.

Write Your Own Code

When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidget Python library. Please see the Use Our Examples section for instructions.

Then, in your code, you will need to reference to the Phidget Python library.

from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a PhidgetInterfaceKit:

from Phidgets.Devices.InterfaceKit import *

Please see the examples on how to add a reference to your particular Phidget.

The project now has access to the Phidget function calls and you are ready to begin coding.

The same teaching section which describes the examples also has further resources for programming your Phidget.

Eclipse with PyDev

Use Our Examples

1. Please ensure that the Phidget Python Module is installed onto your system.

2. Next, download the examples and unpack them into a folder. While these examples were written in Python 3.0, they are also compatible with Python 2.5 (with a minor modification). It is probably best to start with the HelloWorld program, which will work with any Phidget. There is also an example file for your specific Phidget device. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our webpage, and then check the API documentation for it. You will need this example source code to be imported into your project later on.

3. Next, a new project will need to be created. Generate a new PyDev project with a descriptive name such as PhidgetTest.

New Project

4. To import the example program into your project, right click the Project and select Import.

Import File

5. On the next screen, select File System and proceed to the next screen.

Import File

6. Browse to the directory where you extracted the examples into, and select the example you wish to open.

Import File

7. The only thing left to do is to run the examples! Click on Run → Run.

Run?

Once you have the Python examples running, we have a teaching section below to help you follow them.

Write Your Own Code

When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidget Python library. Please see the Use Our Examples section for instructions.

Then, in your code, you will need to include a reference to the Phidget Python library.

from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *

You will also have to add a reference to your particular Phidget. For example, you would include the following line for a PhidgetInterfaceKit:

from Phidgets.Devices.InterfaceKit import *

Please see the examples on how to add a reference to your particular Phidget.

The project now has access to the Phidget function calls and you are ready to begin coding.

The same teaching section which describes the examples also has further resources for programming your Phidget.

OS X

The first step in using Python on Mac is to install the Phidget libraries. Compile and install them as explained on the OS - OS X page, which also describes the different Phidget files, their installed locations, and their roles....

The next step is to install the Phidget Python module. Download it here:

Then, unpack the module and enter the root of the newly unzipped directory. There will be a script in the base directory called setup.py. This is used the same way as most other distributed Python modules - from a command line type:

python setup.py install

This will build the module and install the built python module files into your site-packages directory.

Use Our Examples

First, download the examples:

Unpack them, and enter the root directory. You will find examples specific to each Phidget device, as well as a HelloWorld.py example. The HelloWorld.py code is probably the easiest example to run as it will work with any Phidget device. Or you can use the example specific to your Phidget. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our webpage, and then check the API documentation for it.

The Phidget examples were written in Python 3.0 and this tutorial assumes its use. However, they should still be compatible with Python 2.6. To run the examples using Python 2.5, you will need to modify the example code in the exception handling to read “except RuntimeError, e:”, instead of “except RuntimeError as e:”.

If needed, make those changes to the HelloWorld.py example or the one for your Phidget.

python HelloWorld.py

Write Your Own Code

When writing your code from scratch, you start it as you would any Python code, such as within a text editor like Emacs, Vi, Gedit, or Kate. In your .py source code file, you must include a reference to the Phidget module:

from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *

In addition, you should include the module functions for your specific device. In the case of the Interface Kit, this would be:

from Phidgets.Devices.InterfaceKit import *

For other devices, it would be the software object you found when running the examples above. Then, you would run your Python code the same way as the examples.

To learn how to write your own code for your Phidget, and to learn more about our API, we have a teaching section to help you follow the provided Python examples and which has resources such as the API reference.

Linux

Python has excellent support on Linux.

The first step in using Python on Linux is to install the Phidget libraries. These are the core Phidget libraries, written in C, which when compiled become part of the programming libraries available to your system. Download, compile, and install from the links and instructions on the main Linux page. That Linux page also describes the different Phidget files, their installed locations, and their roles.

The next step is to install the Phidget Python module. Download it here:

Then, unpack the module and enter the root of the newly unzipped directory. There will be a script in the base directory called setup.py. This is used the same way as most other distributed Python modules - from a command line type:

python setup.py install

This will build the module and install the built python module files into your site-packages directory.

Use Our Examples

First, download the examples:

Unpack them, and enter the root directory. You will find examples specific to each Phidget device, as well as a HelloWorld.py example. The HelloWorld.py code is probably the easiest example to run as it will work with any Phidget device. Or you can use the example specific to your Phidget. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our webpage, and then check the API documentation for it.

The Phidget examples were written in Python 3.0 and this tutorial assumes its use. However, they should still be compatible with Python 2.6. To run the examples using Python 2.5, you will need to modify the example code in the exception handling to read “except RuntimeError, e:”, instead of “except RuntimeError as e:”.

If needed, make those changes to the HelloWorld.py example or the one for your Phidget.

Then, if you have not set up your udev rules for USB access, you will need to run the Python example as root:

sudo python HelloWorld.py

Write Your Own Code

When writing your code from scratch, you start it as you would any Python code on Linux, such as within a text editor like Emacs, Vi, Gedit, or Kate. In your .py source code file, you must include a reference to the Phidget module:

from Phidgets.PhidgetException import *
from Phidgets.Events.Events import *

In addition, you should include the module functions for your specific device. In the case of the Interface Kit, this would be:

from Phidgets.Devices.InterfaceKit import *

For other devices, it would be the software object you found when running the examples above. Then, you would run your Python code the same way as the examples.

To learn how to write your own code for your Phidget, and to learn more about our API, we have a teaching section to help you follow the provided Python examples and which has resources such as the API reference.

Follow the Examples

By following the instructions for your operating system and compiler above, you probably now have a working example and want to understand it better so you can change it to do what you want. This teaching section has resources for you to learn from the examples and write your own.

Your main reference for writing Python code will be our Python API information, with syntax for all of our functions:

  • Python API (This is the complete set of functions you have available for all Phidgets)
  • Device Specific APIs - The one for your Phidget can be found in its user guide.

To learn the details behind opening, configuring, using, and closing your Phidget, try the General Phidget Programming page. That page also describes using the Phidget in an event-driven manner and in a traditional manner, both of which are available in Python.

Example Flow

The Hello World example has this general structure so you can follow along. We also have an in-depth general introduction to writing Phidget code (like open, read data, etc), as well as the Python API for specific syntax:

// ----- Event and Other Functions -----

Create any Language-Specific Functions (exception handling)

Create General Attach, Detach, and Error Handling Functions:

On attach: Print Hello Message
On detach: Print Goodbye Message

 

In Python, you can name these event functions whatever you like. You will then pass their function names to the Phidget library below in the Main Code section. This hooks them into the actual events when they occur.
In the example code, the event functions common to all Phidgets are called things like AttachHandler() and DetachHandler(), etc.

Some event functions will be specific to each device, like when a tag is read on an RFID board, or when a sensor value changes on an Interface Kit. Other functions are given in the examples to show you more detail on using your Phidget. For example, DeviceInitialize() will show what needs to be set up for your Phidget before using it.

// ----- Main Code -----

Create Manager Software Object
Hook Event Functions created above to Device
Open Device

Wait for 'Enter' key character input
Handle on-going attach and detach events
Print Hello and Goodbye messages
Exit upon input

Close Device

Delete Device

 

Creating a Phidget software object in Python is specific to the Phidget. For a Phidget Spatial, for example, this would involve creating a Spatial object. The examples show how to do this and other API functions.

The object provides device specific methods and properties which are available from the API for your specific Phidget.

Code Snippets

Specific calls in Python will differ in syntax from those on the General Phidget Programming page, but the concepts stay the same.

It may help to have the General Phidget Programming page and this section open at the same time, because they parallel each other and you can refer to the Python syntax. However, many additional concepts are covered on the General Phidget Programming page on a high level, such as using multiple Phidgets, handling errors, and different styles of programming.

For example, if we were using a Phidget Interface Kit as our device, the general calls would look like this:

Step One: Initialize and Open

# Create
try:
  device = InterfaceKit()	
except RuntimeError as e:
  print("Runtime Error: %s" % e.message)

# Open
try:
  device.openPhidget()
except PhidgetException as e:
  print (Phidget Exception %i: %s % (e.code, e.detail))		
  exit(1)

The variable device is now a handle for the Phidget. This example is specific to the Interface Kit because the call InterfaceKit() is used. For another device, use the correspondingly named call in the Python API.

The handle device is then used for all the Python function calls using the Phidget for its device-specific functions - in this case, Interface Kit specific functions. Every type of Phidget also inherits functionality from the Phidget base class.

Note that open() opens the software object, but not hardware. So, it is not a guarantee you can use the Phidget immediately. The different types of open can be used with parameters to try and get the first device it can find, open based on its serial number, or even open across the network. The API manual lists all of the available modes that open provides.

Also note that you can catch exceptions thrown by the Phidget library as we did above when using the openPhidget() call. In other words, this should probably be present around most of your Phidget calls, especially when you are learning how to use the Phidget and debugging your code:

try:
  # Your code goes here
except PhidgetException as e:
  print (Phidget Exception %i: %s % (e.code, e.detail))		
  exit(1)

Step Two: Wait for Attachment (plugging in) of the Phidget

To use the Phidget, it must be plugged in (attached). We can handle this simply by calling waitForAttachment. This function works for any Phidget. WaitForAttachment will block indefinitely until a connection is made to the Phidget, or an optional timeout is exceeded:

device.waitForAttach(10000)
print ("%d attached!" % (device.getSerialNum()))

Sometimes, it makes more sense to handle the attachment via an event. This would be in instances where the Phidget is being plugged and unplugged, and you want to handle these incidents. Or, when you want to use event-driven programming because you have a GUI-driven program. In these cases, an event-driven code snippet to handle the attachment might look something like this:

def AttachHandler(event):
    attachedDevice = event.device
    serialNumber = attachedDevice.getSerialNum()
    deviceName = attachedDevice.getDeviceName()
    print("Hello to Device " + str(deviceName) + ", Serial Number: " + str(serialNumber))

# Insert code for -creating- device here....

try:
    device.setOnAttachHandler(AttachHandler)
except PhidgetException as e: 
    # Insert code for handling any exceptions
    # A common exception will occur if you do not create the device properly above

# Insert code for -opening- device here....

Step Three: Do Things with the Phidget

You can read data and interact with your Phidget both by polling it for its current state (or to set a state), or by catching events that trigger when the data changes.

For our | Phidget Interface Kit, the polling method of getting the current sensor state and setting an output state looks something like this:

# Get a data point from Analog Port 0
device.getSensorValue(0)

# Set digital output port 0 to be on
device.setOutputState(0, 1)

To catch data changes via events, you would use something like this:

def sensorChanged(e):
  print (Sensor %i: %i % (e.index, e.value))
  return 0

# Insert code to create an Interface Kit called 'device'

# Hook our function above into the device object
device.setOnSensorChangeHandler(sensorChanged)

# Insert code to open 'device'

Step Four: Close and Delete

At the end of your program, don’t forget to call closePhidget() to free any locks on the Phidget that the openPhidget() call put in place!

device.closePhidget()

More How-To's

The General Phidget Programming page gives more information about:

The complete set of functions you have available for all Phidgets can be found in the Python API. You can also find more description on any device-specific function in the Device API page for your specific Phidget, which can be found in its user guide.

Common Problems and Solutions/Workarounds

OS X: My application hangs when using multiple devices in a single Python application.

A call to open may hang indefinitely if multiple devices are being programmed in a single Python application. To circumvent this, allow the application to delay a short period between open calls. For most environments, a 1.25 millisecond delay is enough. For example:

import time
...
interface_kit.openPhidget(94695)
time.sleep(0.00125)
rfid.openPhidget(33502)


All Operating Systems: The examples produce an error while running in a Python 2.5 environment.

Running the examples produces an error similar to the following:

InterfaceKit-simple.py:33: Warning: 'as' will become a reserved keyword in Python 2.6
  File "InterfaceKit-simple.py", line 33
    except RuntimeError as e:
SyntaxError: invalid syntax

To run the example code in Python 2.5, all the lines containing:

except RuntimeError as e:

will need to be replaced with:

except Runtime, e:

And then it should run.