Windows with LabVIEW
Welcome to using Phidgets with LabVIEW! By using LabVIEW, you will have access to the complete Phidget22 API, including events. We also provide example code in
LabVIEW for all Phidget devices.
LabVIEW is a development environment for a graphical programming language created by National Instruments.
Requirements
First, make sure you have the following:
● Phidgets Drivers for Windows installed(see Part 1 of this user guide)
● Phidget LabVIEW Library downloaded
Note: The LabVIEW Library also contains example VI trees, which we'll cover later in this guide.
Using Our Examples
One of the best ways to start programming with Phidgets is to use our example code as a guide.
Unpack the Phidget LabVIEW Library and rename the unpacked folder
to Phidgets.
Using Our Examples
Navigate to the following directory:
● For 32-bit LabVIEW, C:/Program Files (x86)/National Instruments/LabVIEW 20xx/instr.lib
● For 64-bit LabVIEW, C:/Program Files/National Instruments/LabVIEW 20xx/instr.lib
Place the renamed folder at this location:
Using Our Examples
Next, open LabVIEW and create a new VI:
Using Our Examples
In the new block diagram window, open the functions palette (View -> Functions Palette).
Next, go to the Phidgets palette (Instrument I/O -> Instrument Drivers -> Phidgets):
Using Our Examples
Next, select a palette that will work for your Phidget and drag VI Tree.vi onto your block diagram:
Using Our Examples
Right-click on VI Tree.vi and select Open Front Panel:
Using Our Examples
From the front panel, navigate to the block diagram (Window -> Block Diagram):
Using Our Examples
The VI Tree Block Diagram lists all VIs available for its Phidget Class, and which subpalette to find them under. The examples are located near the bottom of
the block diagram. Right-click the example you would like to use and select Open Front Panel:
Using Our Examples
When you are ready, press Run and the application will demonstrate the Phidget's functionality.
Here is an example of an Accelerometer channel on a Spatial Phidget:
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 environment and writing your own code!
Configure Your Environment
First, we recommend enabling the Show constant labels setting in LabVIEW. This setting will reduce complexity when developing, and is especially
recommended for beginners.
To enable the setting, first navigate to Tools -> Options on your block diagram:
Configure Your Environment
Select the Environment category and enable Show created constant labels at the bottom:
Configure Your Environment
To begin working with Phidgets, you will need both a StartPhidget VI and a ClosePhidget VI:
Configure Your Environment
Select a class that will work with your Phidget from the drop-down menu for each VI:
Configure Your Environment
You can now add device information or any initialization parameters to the StartPhidget VI. Using your mouse, hover over each of the connection nodes to see
information about it:
Configure Your Environment
If you would like to add device information or initialization parameters, right-click the connection node and navigate to one of the following:
● Create -> Constant
● Create -> Control
Configure Your Environment
Creating a constant will allow you to modify device information from the block diagram:
Configure Your Environment
Creating a control will allow you to modify device information from the front panel:
The environment now has access to Phidgets. Next, we'll walk through writing your own code.
Write Code
Along with this guide, your main resources for writing LabVIEW code will be:
● The examples
● The Phidget22 API
● The VI help files
Examples of more complex general topics such as using multiple Phidgets and connecting to a Phidget over the Network Server can be found under the VI Tree for
the Phidget Common palette.
Example Flow
Most LabVIEW examples follow the same basic flow: starting a Phidget, reading some data, and closing the Phidget.
Step One: Initialize, Open And Wait For Attachment Of The Phidget
The entire process of opening and initializing a Phidget can be done by using the version of StartPhidget.vi that corresponds to your device. In most
cases, StartPhidget.vi will also attempt to wait for the first data to become available from the device for 5 seconds after initialization.
If you'd prefer to initialize the device manually, you can use OpenPhidget.vi for your device and call the individual functions to set up the device.
Step Two: 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.
To poll devices, simply place the corresponding blocks:
To use events, there are three main blocks for each type, to create, execute, and close the event handler. When creating the event, all devices using an event
of the same type must be grouped into an array to ensure the events get processed correctly.
Step Two: Do Things With The Phidget
Once created, the events will be processed by [Name]EventExe.vi. When an event occurs, the pertinent information will be output, as well as information
to reference which device caused it.
After a program has run its course, the event handler must be closed.
Step Three: Close And Delete
Closing a Phidget is done by using the appropriate version of ClosePhidget.vi
That's all the basic building blocks you need to create a LabVIEW program using Phidgets.
Help and Documentation
For more information on the use of any VI and its parameters, right-click the VI and select Help
Help and Documentation
This will take you to an HTML page outlining the function of the VI. This includes a list of all its parameters, which devices support them, their range of
acceptable values, and their default values, where applicable:
What's Next?
Now that you've set up Phidgets in your programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.
Continue reading below for advanced information and troubleshooting for your device.
Scroll down for device-specific troubleshooting, or go to the next slide for LabVIEW troubleshooting.
LabVIEW Troubleshooting
Expand All
What this means is you probably aborted the VI which stopped the program before the Phidget could be closed. Aborting execution will not release the Phidget device properly and will consequently make it unusable until the Phidgets library (or LabVIEW) has been restarted.
To resolve this, you may open a new VI, place PhidgetResetLibrary.vi, and run it. This will completely reset the current Phidget library, making it possible again to connect to all Phidgets.
Note that this action will close all Phidgets that are currently open in LabVIEW, and should not be used while other Phidgets-related LabVIEW VIs are running.
In order to prevent this from happening you should use a software stop button when possible instead of halting operation. That way the Close subVI gets called and the Phidget will be released.
All Phidgets-based error codes in LabVIEW are offset by 7000 to avoid conflicting with LabVIEW's own error codes. To get the equivalent Phidget return code from the LabVIEW error code, simply subtract 7000. For instance, error code 7003 in LabVIEW translates to Phidget Return Code 3.
To find the meaning of all Phidget Return Codes, you can go to the Phidget22 API page, and open the PhidgetReturnCode section under Enumerations.
In other words, if you open 2 of the same device and have a sensor change event for each one your system can behave unpredictably. This problem is a quirk in the way that LabVIEW handles passing events to and from C. There are a few solutions to this issue, either:
- Stop using events and simply poll the device. Events work similarly to polling in LabVIEW anyway and should not cause substantial performance changes to your application.
- Implement a simple fix to the events which are causing the problem. The pointer is identical in the case where two events of the same type are passed from a single function. This causes the events in C to output to the same event in LabVIEW. To get around this you need to copy the offending subVI, then change the name of the cluster object in it from "Event" to something else (your choice), change the name of the .vi to something else and then use those two different subVIs in your program. You would need to repeat this for each subsequent event of the same type you wish to have.
- Make an array of all the devices you intend to use with the event, and feed the array into a single EventCreate vi, and use a single EventExe handler for all the events. When using this method, it might be tempting to add multiple event handlers, but keep in mind that events only occur once, in whichever handler sees them first. When running multiple Phidgets through the single event handler, you can determine which one caused the event by comparing the phid terminal from the EventExe VI to the Phidget IDs (Device In/Device Out) of your Phidgets.
We recommend using either of the the first two solutions where possible. The first is a bit cleaner, but the second will work just as well. We only recommend using the third method in cases where it is not practical to manually create individual event handlers.
