Difference between revisions of "Language - Visual Basic .NET"

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Line 125: Line 125:
  
 
==Write Code==
 
==Write Code==
 +
{{WriteCode_Intro}}
  
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.
+
=== Step One: Initialize and Open ===
Your main reference for writing VB.NET code will be the {{Phidget22API}} Manual.
+
You will need to declare your Phidget object in your code. For example, we can declare a digital input object like this:
 +
<syntaxhighlight lang='vbnet'>
 +
ch = New Phidget22.DigitalInput()
 +
</syntaxhighlight>
  
=== Code Snippets ===
 
  
The following code snippets describe how to do various general tasks with Phidgets. You should be able to find places in the examples where these snippets exist, and modify them to suit your requirements.
+
Next, we can open the Phidget object like this:
 +
<syntaxhighlight lang='vbnet'>
 +
ch.Open()
 +
</syntaxhighlight>
  
==== Step One: Initialize and Open ====
 
 
The Open() function opens the software object, but not hardware. So, it is not a guarantee you can use the Phidget immediately.
 
 
For example, if we were using an Digital Input as our device, the create and open calls would look like this:
 
  
 +
Although we are not including it on this page, you should include error handling for all Phidget functions. Here is an example of the previous code with error handling:
 
<syntaxhighlight lang='vbnet'>
 
<syntaxhighlight lang='vbnet'>
device = New Phidget22.DigitalInput()
+
Try
device.Open()
+
  ch = New Phidget22.DigitalInput()
 +
  ch.Open()
 +
Catch ex As PhidgetException
 +
  errorBox.addMessage("Error initializing: " + ex.Message)
 +
End Try
 
</syntaxhighlight>
 
</syntaxhighlight>
  
==== Step Two: Wait for Attachment (plugging in) of the Phidget ====
+
=== Step Two: Wait for Attachment (plugging in) of the Phidget ===
 
+
Simply calling open does not guarantee you can use the Phidget immediately. To use a Phidget, it must be plugged in (attached). We can handle this by using event driven programming and tracking the attach events. Alternatively, we can modify our code so we wait for an attachment:
To use the Phidget, it must be plugged in (attached). We can handle this simply by calling open with a number as a parameter in place of the basic open. This function works for any Phidget. This will block until a connection is made to the Phidget, or the specified timeout is exceeded:
+
 
+
 
<syntaxhighlight lang='vbnet'>
 
<syntaxhighlight lang='vbnet'>
device.Open(5000);
+
ch = New Phidget22.DigitalInput()
 +
ch.Open(5000);
 
</syntaxhighlight>
 
</syntaxhighlight>
 +
Waiting for attachment will block indefinitely until a connection is made, or until the timeout value is exceeded
  
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:
 
  
 +
To use events to handle attachments, we have to add the following code:
 
<syntaxhighlight lang='vbnet'>
 
<syntaxhighlight lang='vbnet'>
Private Sub device_Attach(ByVal sender As Object, ByVal e As Phidget22.Events.AttachEventArgs) Handles device.Attach
+
Private Sub device_Attach(ByVal sender As Object, ByVal e As Phidget22.Events.AttachEventArgs) Handles ch.Attach
  Dim attachedDevice As Phidget22.Phidget = CType(sender, Phidget22.Phidget)
+
   Console.WriteLine("Phidget Attached!");
  Dim serialNumber as Integer
+
  Dim deviceName as String
+
  serialNumber = attachedDevice.DeviceSerialNumber;
+
  deviceName = attachedDevice.DeviceName;
+
   Console.WriteLine("Hello Device {0},  Serial Number: {1}!", deviceName, serialNumber.ToString());
+
 
End Sub
 
End Sub
 
</syntaxhighlight>
 
</syntaxhighlight>
  
==== Step Three: Do Things with the Phidget ====
+
=== Step Three: Do Things with the Phidget ===
We recommend the use of event driven programming when working with Phidgets. This allows the program to execute other tasks until the Phidget generates a new event. You can hook a custom function into an event trigger like this, using a Digital Input Phidget as an example:
+
We recommend the use of event driven programming when working with Phidgets. In a similar way to handling an attach event as described above, we can also add an event handler for a state change event:
 
+
 
<syntaxhighlight lang=vbnet>
 
<syntaxhighlight lang=vbnet>
Private Sub device_DigitalInputChange(ByVal sender As Object, ByVal e As Phidget22.Events.DigitalInputStateChangeEventArgs) Handles device.StateChange
+
Private Sub device_DigitalInputChange(ByVal sender As Object, ByVal e As Phidget22.Events.DigitalInputStateChangeEventArgs) Handles ch.StateChange
   textBox1.Text = "State: " + e.State;
+
   stateText.Text = "State: " + e.State;
 
End Sub
 
End Sub
 
</syntaxhighlight>
 
</syntaxhighlight>
  
Some values can be directly read and set on the Phidget. These functions can be used inside a polling loop as an alternative to event driven programming. The line inside the loop would be something like this, after which you could do something with the value:
 
  
 +
If events do not suit your needs, you can also poll the device directly for data using code like this:
 
<syntaxhighlight lang=vbnet>
 
<syntaxhighlight lang=vbnet>
val = device.State;
+
state= device.State;
 
+
stateText.Text = "State: " + e.State;
device.State = true;
+
 
</syntaxhighlight>
 
</syntaxhighlight>
  
==== Step Four: Close and Delete ====
+
=== Step Four: Close and Delete ===
At the end of your program, be sure to close your device.
+
At the end of your program, be sure to close and delete your device:
 
+
 
<syntaxhighlight lang=vbnet>
 
<syntaxhighlight lang=vbnet>
Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
+
device.Close();
    device.Close();
+
End Sub
+
 
</syntaxhighlight>
 
</syntaxhighlight>
  

Revision as of 21:52, 9 June 2017


Quick Downloads

Documentation

Example Code

Libraries

Getting Started with VB.NET

Welcome to using Phidgets with VB.NET! By using VB.NET, you will have access to the complete Phidget22 API, including events. We also provide example code in VB.NET for all Phidget devices.

Windows

If you haven't already, please visit the Windows page before you continue reading. There you will be instructed on how to properly set up your Windows machine so you can follow the guides below!

Visual Studio

Use our examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. In order to run the examples, you will need to download and install Microsoft Visual Studio.


Now that you have Microsoft Visual Studio installed, select an example that will work with your Phidget:


Open the example project and start the example by pressing the Start button:


Csharp visualstudio run.png


The application will open the Phidget, list basic information about the Phidget, and demonstrate the Phidget's functionality. Here is an example of a Digital Output channel on a RFID Phidget:


Csharp visualstudio rfid.PNG


You should now have the example up and running for your device. Play around with the device and experiment with some of the functionality. When you are ready, the next step is configuring your project and writing your own code!

Configure your project

When you are building a project from scratch, or adding Phidget functionality to an existing project, you'll need to configure your development environment to properly link the Phidget .NET library. To begin:


Create a new Windows Forms Application project:


Vbnet newproject.PNG


Next, right-click to add a reference to the Phidget .NET library:


CSharp VS2015 Add Reference.png


On the following screen, click Browse... and navigate to the location of Phidget22.NET.dll:

  • C:\Program Files\Phidgets\Phidget22\Phidget22.NET.dll


CSharp VS2015 Add Reference 2.png


Finally, to include the Phidget .NET library, add the following lines to main window class file:

Imports Phidget22
Imports Phidget22.Events

Success! The project now has access to Phidgets. Next, view the write your own code section located below.

Mono

Use Our Examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. In order to run the examples, you will need to download and install Mono for Windows.


Now that you have Mono installed, download and unpack the HelloWorld example for C#:

Note: The HelloWorld example is compatible with Mono because it does not use Windows Forms. All other C# examples use Windows Forms.


Next, copy Phidget22.NET.dll from type the following location:

  • C:\Program Files\Phidgets\Phidget22\Phidget22.NET.dll


Place both the HelloWorld example and the Phidget22.NET.dll file in the same location. Your folder should now look something like this:

Vbnet folder.PNG


Open the command prompt at the folder location and enter the following command:

vbnc /r:Phidget22.NET.dll Module1.vb

This will create an executable file called Module1.exe. Type in the following command to run the example:

mono Module1.exe


Vbnet mono.PNG


You should now have the example up and running. When you are ready, the next step is configuring your project and writing your own code!

Configure your project - IN PROGRESS (LUCAS)

When you are building a project from scratch, or adding Phidget functionality to an exisiting project, you'll need to configure your development environment to properly link the Phidget .NET library.

To include the Phidget .NET library, simply add the following lines to your code:

Imports Phidget22
Imports Phidget22.Events

The project now has access to Phidgets. Next, view the write your own code section located below.

Write Code

By following the instructions for your operating system and compiler above, you now have working examples and a project that is configured. This teaching section will help you understand how the examples were written so you can start writing your own code.


Remember: your main reference for writing {{{1}}} code will be the Phidget22 API Manual and the example code.

Step One: Initialize and Open

You will need to declare your Phidget object in your code. For example, we can declare a digital input object like this:

ch = New Phidget22.DigitalInput()


Next, we can open the Phidget object like this:

ch.Open()


Although we are not including it on this page, you should include error handling for all Phidget functions. Here is an example of the previous code with error handling:

Try
  ch = New Phidget22.DigitalInput()
  ch.Open()
Catch ex As PhidgetException
  errorBox.addMessage("Error initializing: " + ex.Message)
End Try

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

Simply calling open does not guarantee you can use the Phidget immediately. To use a Phidget, it must be plugged in (attached). We can handle this by using event driven programming and tracking the attach events. Alternatively, we can modify our code so we wait for an attachment:

ch = New Phidget22.DigitalInput()
ch.Open(5000);

Waiting for attachment will block indefinitely until a connection is made, or until the timeout value is exceeded


To use events to handle attachments, we have to add the following code:

Private Sub device_Attach(ByVal sender As Object, ByVal e As Phidget22.Events.AttachEventArgs) Handles ch.Attach
  Console.WriteLine("Phidget Attached!");
End Sub

Step Three: Do Things with the Phidget

We recommend the use of event driven programming when working with Phidgets. In a similar way to handling an attach event as described above, we can also add an event handler for a state change event:

Private Sub device_DigitalInputChange(ByVal sender As Object, ByVal e As Phidget22.Events.DigitalInputStateChangeEventArgs) Handles ch.StateChange
  stateText.Text = "State: " + e.State;
End Sub


If events do not suit your needs, you can also poll the device directly for data using code like this:

state= device.State;
stateText.Text = "State: " + e.State;

Step Four: Close and Delete

At the end of your program, be sure to close and delete your device:

device.Close();

Further Reading

Phidget Programming Basics - Here you can find the basic concepts to help you get started with making your own programs that use Phidgets.

Data Interval/Change Trigger - Learn about these two properties that control how much data comes in from your sensors.

Using Multiple Phidgets - It can be difficult to figure out how to use more than one Phidget in your program. This page will guide you through the steps.

Polling vs. Events - Your program can gather data in either a polling-driven or event-driven manner. Learn the difference to determine which is best for your application.

Logging, Exceptions, and Errors - Learn about all the tools you can use to debug your program.

Phidget Network Server - Phidgets can be controlled and communicated with over your network- either wirelessly or over ethernet.