General Troubleshooting

From Phidgets Support
Revision as of 20:17, 9 January 2012 by Cora (talk | contribs)


To troubleshoot a problem with a Phidget device or program, we strongly recommend using a logical approach to pin down the source. Although Phidgets are designed to be easy to use, they actually are a complex system with many levels of interfacing between the Phidget, cables, possible networking, operating systems, USB ports, the Phidget Libraries, and ultimately your code.

To help you narrow down the source of the problem into a specific part of the overall system, we provide an overview of the entire system below. In each grey box we show the affected parts of the system (computer platform, the Phidget, your code, etc) and a simple step or two you can take to see if the problem is within that part of the overall system.

Once you have found the part of your system with the problem, click on the green link within the box to learn more about how to troubleshoot that portion.

Troubleshooting.png

The content that you need to solve your problem probably exists somewhere within our documentation. We cover everything from compiling the Phidget Libraries for embedded systems, to using our example on Visual Studio 6, to how Solid State Relays actually work. The purpose of this page, then, is to distill the problem you have enough that you can get to the documentation you need.

Quick Links

The sections linked from the image above are:

Code Troubleshooting

To determine whether the problem is in your code, you should run the provided examples for your programming language.

  • If the examples run, the problem is within your code.
  • If the examples do not run, the problem is at a lower level in the system. Read on to the operating system troubleshooting section below.

If the problem is in your code...

  • Syntax help can be found in the API download and code snippets for your programming language
  • High-level concept help (logging, catching errors, using the API) is on the General Phidget Programming page
  • Generic API help (error types and codes, information about each function) is on the General API page.
  • Help using hardware in code (number of ports returned in code, maximum software sampling speed) can be found in the Software/API section on the page for your device
  • Compiler help (linking libraries, running code) can be found on the page for your language
  • Ensure you wait enough time for the Phidget to respond to your requests, such as when switching between ratiometric and non-ratiometric sensing, or to get and set device data.

To download and run the examples, visit the page about your programming language. The Software/API section within the page for your device will tell you the software object -- and thus example file name -- for your Phidget. Make sure to use either that device-specific example, or the HelloWorld example if there is not an example specifically for your device.

When debugging, it helps to extract from your code what is known as a Minimum Reproducible Unit (MRU). This is the minimum lines of code that can reproduce the issue. We can help with this. An MRU will allow you to find what part of your use of Phidgets in code is causing the problem. Extracting an MRU is a powerful process which can not only isolate the problem, but also allow you to examine and organize your code. Also, it helps us debug your problem faster if you can show exactly what the problem is in your Phidget API code.

If you have found problematic lines and want to see what is wrong, you can turn on Phidget logging. Logging can save and display many different levels of messages (errors, debugging, or even individual Phidget library actions) to either a file or the program console. You can find help to turn logging on and off in the logging section of our General Phidget Programming guide.

Note: We do not offer services to debug general programming projects, or to develop code from scratch. We do, however, support any and all questions about the Phidgets and their use. So, if you have ideas for helpful examples, more documentation, or other useful material we could provide, we welcome your suggestions!

Operating System Troubleshooting

To determine whether the problem is in your operating system, you should check whether your system detects the Phidget by following the Troubleshooting section on the page for your operating system. Commonly, this is done with:

  • The Device Manager in Windows
  • The "About This Mac" menu in Mac OS X
  • The kernel logs via dmesg | tail in Linux

If you plug in the Phidget and the system shows:

  • It does not appear, or
  • It does not disconnect, or
  • It only appears sometimes

The problem is probably in the communication portion of the system, or at a lower level. Start with the Communications Troubleshooting section below and work your way down.

If the problem is with your operating system...

If, on the other hand, your computer consistently detects the Phidget on the USB port but the libraries fail to communicate with it (i.e. the provided examples do not run, as described above), the problem is probably (a) your Phidget library versions, (b) other, third-party drivers causing a conflict, or (c) your operating system. Details about these problems for each platform can be found in the Troubleshooting section on the page for your operating system.

Communications Troubleshooting

To determine whether the problem is a communications problem, check operation using the shortest, most direct connection you can, including both:

  • Data connections, and
  • Power connections

If you believe a connection may be at fault:

  • Use short USB cables (<5 m)... long wires lead to poor sensor data and/or inadequate power
  • Use powered USB hubs or direct connections to a computer.
  • Try unplugging everything on the hub except the Phidget.
  • Make sure any cables between Phidgets are correctly connected. Helpful pictures can be found on the Getting Started page for your device
  • If your Phidget needs external power, such as the motors and relays, the proper way to provide it can be found on the product page for your device

Communication problems come from either (a) power issues, or (b) connection issues. Once everything is plugged in and powered properly, there is not a whole lot that can go wrong with cables. The proper way to provide additional power (only needed for some devices such as motors and relays, most Phidgets get power directly from USB) can be found on the product page for your device.

The one exception to communications problems being only from power or connections is if you're using a wireless internet connection to the Single Board Computer. Help for setting up and troubleshooting that Wifi connection can be found on its product page.

Webservice Troubleshooting

Quick Fixes...
Make sure the Phidget library versions are the same on both computers. The Webservice and libraries are on the page for your operating system
Wait a little time before trying to do things with the Phidget upon first connecting remotely, sometimes delay occurs over a network
Check the network setup on both sides (IP address and port correct? Server name spelling? User name and password?)

To narrow down the problem to the Webservice, try using the Phidget only on the directly connected system. Then, if possible, also try using the Phidget on the remotely controlling system. (Some platforms only allow remote use, so this may not be possible.)

If the Phidget works locally on both ends but not remotely, the problem is with the Webservice. First, try slowing your program down. Sometimes a network will introduce a bit of delay. This will primarily affect how quickly you can use the Phidget after opening and attaching it, as well as the speed of reading continuous data from the device. Using a sleep or wait function for short periods at these points will slow down your program. If the program works when slowed, network lag is probably at fault.

Another problem might be an error in the numerous details that need to match on each computer. You either need an IP address and port, or the server name (when using muticast DNS from Bonjour on Windows and Mac OS X or avahi on Linux). The server name is set at the Webservice start up, or it will default to the name of the computer with the direct connection. Double-checking all of these details may uncover the problem.

Finally, if you suspect multicast DNS may be the problem, use the IP address and port form of open() (if you can) to directly connect to the computer controlling the Phidget.

Device Troubleshooting

Quick Fixes...
What your device can and can't do (power, functionality, etc) will be found on its product page.
Make sure all the pieces are hooked up correctly. Helpful photos can be found on the Getting Started page for your device.
If you're trying to do something especially involved, become well-versed in your hardware. We provide lots of education on our primer pages.

An easy way to tell you have a new problem with your device is that it suddenly stops working. If you run the same code, on the same system, with the same libraries, and the same Phidget and suddenly it doesn't do the same thing anymore, you almost certainly have a hardware problem.

This can happen especially on boards and/or components that handle some form of external power (motors, relays, etc). It is important to make sure you don't overload the board, or you could do some serious damage. Check the specs for your device and remember, be conservative!

However, sometimes you get a board right out of the box and it doesn't seem to work. Some Phidgets, being flexible to many tasks, have their own connections between sensors, batteries, power, intermediate boards (like temperature), and so on. Although usually this is an intuitive hookup process, take another look at the photos in the Getting Started Guide for your device and make sure all the wires are in their proper place.

Once you have confirmed this, slow down and (if you haven't already) work carefully through the setup process. starting with that same Getting Started Guide for your device - to make sure it is indeed a problem with the hardware. This troubleshooting page itself shows that even something as simple as a device "not working" could be due to a problem at several different points.

Contact Us

If you are still having trouble after working through this guide, please contact us.

It helps if you can you can give us precise information about your issue, such as:

  • Minimal code to reproduce the problem
  • What part of the system you think the issue might be in, and why
  • And, of course, photos or even videos (we love these)!
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