How to get the system network status in Qt like we get event hits in .NET so that each and every time when we connect network get a signal of a status of the network connection?
Is there any function that have same functionality as I mentioned above?
Using ping and other methods of network configuration takes a small amount of time.
But I need to display it as fast as I could other than using a specific port to listen to the socket and display its error.
Can any one help me out of it?
I found a good example of getting network information using QT:
http://developer.nokia.com/community/wiki/Get_Network_information_using_Qt
For instance, you can get the signal strength from the public member, networkSignalStrength, of QSystemNetworkInfo. And, if you take a look at QSystemNetworkInfo class reference, you can find signals such as networkSignalStrengthChanged so that you can handle something when network signal strength gets changed.
Hope this helps!
Related
I am a beginner in Android and testing Android code in which I am receiving and sending data through UART communication.
Hardware for communication- MAX232 device which is connected to Raspberry Pi3 Model B and the other part of MAX232 is connected to Vending Machine Port(Rx,Tx,Gnd to communicate my android app with the Vending Machine). My communication breaks SPORADICALLY and then starts communicating.
I do not know what the reason is
If anyone can help me in this, please suggest. Or any other information will be needed,I will share
private static final String UART_DEVICE_NAME = "UART0"; // define in my code.
**
I have to use ttyAMA0(PL011 UART) port because baudrate does not
change with the core frequency like with ttyS0(MIniUART)
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For example: If I send 100 commands one by one, I get 2-5 times this
error.
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> ERROR: Failed to open /dev/ttyAMA0: No such file or directory
**
Same thing happens to me reading data. I do not talk to the device (particle photon) connected to it, just listen. Since i'm expecting a response frequently, anything more than a couple seconds means things have gone south on one side or the other. It didn't seem likely though that my photon code was bad, as I had done many day-long tests with other things reading the data (arduino IDE, whatever).
Anyway, I created a runnable that fires every few seconds and checks when the last received response was. If it exceeds 60 seconds (things are most certainly wrecked and not going to get any better), I'll attempt to start up the connection again (Periperhal manager's openUartDevice). The main code waits another 60 seconds before trying again if it still has not received a response.
I also added code in 'onUartDeviceError' to trigger a callback the second that goes bad (not really sure if that's ever been the culprit in this), which will attempt the same restart logic but with a much smaller wait (like 5 seconds).
Lastly I made the Pi reboot itself (and thus the attached photon) so everything starts fresh, every morning at 6am. This has solved the issue for my purposes and its been in service for somewhere in the neighborhood of two years. Due to this reliability issue I don't do anything important with the pi, it simply exists to aggregate data from a few places and provide JSON. The photon is much more reliable even if the pi stops listening to it, so it controls the important/dangerous stuff (heaters, lithium batteries). Hopes this helps a little, but maybe some reconnect logic would solve the problem.
I was wondering if it was possible to be able to control/get the system volume, get network information (i.e is it a wired or wireless connection, name of network, etc.) and get battery information with VB.Net using Mono on Ubuntu 12.10? Thanks.
You can use the System.Diagnostics.Process class to call out to the shell and invoke the commands / get the information you require. There is an example here.
I am developping a project about data sampling and realtime display like oscilloscope. The data are transfered to PC with virtual com port at a high trandfer rate. I am using QT4.8.4 + Qextserialport to accomplish serial port communication on WindowsXP.
I have tested the device using AccessPort. It could receive the data from the port, but have no response to write to it. If I wanted to make the device stop uploading data, I must stop the device and write stop command to it, restarted the device, then the device stopped uploading. It is the same for the application using one thread to process reading and writing. I did not want to close the port completely. I just wanted to enter some command to change something, the sampling rate, the data format, etc.
So, I tried multithread. I downloaded a reference code from the following link.
http://www.qtcentre.org/threads/21063-QextSerialPort-with-QTimer-approch-for-reading?p=103325&highlight=#post103325
(I am sorry, I really do not know how to paste code fitly on this site)
In this code, the author derived two subclass of QThread. One is for reading port, the other is for writing port. He also reimplemented the run() in these two subclass. I tried this code, but found that when receiving code, my GUI frozen.
It seem that the author in the following thread met the same question with me.
Qt: GUI sometimes freezing when using threads and signals/slots
But I have question about this thread.
The author mentioned "When running the code in the GUI-thread, there is no problem."
Did the author mean that everything is OK when the all code in GUI-thread? So, why he used worker thread and process thread?
The author mentioned "Process thread"
Do I need a another process thread to work with GUI thread which is responsible for display?(I need to display not only the data but also the waveform, all must in realtime)
Please give me some tips on how to conquer this problem. Thanks a lot.
The short answer is yes. Doing any heavy processing on a GUI thread will result in freezing the GUI (esp if you block). Instead you should either have an independent thread that updates the data, or spin off worker threads for specific tasks. In either case, when there is new data to display you should signal the GUI thread when there is new data to display. If possible, I'd recommend using the MVC pattern and implement a QAbstractItemModel to provide data to your view (as it has a defined pattern for providing those updates).
I am using MonoTouch to develop an app which will connect to remote devices on a network. These devices have data which can be access through http queries.
If I provide a valid IP address to a controller the app works perfectly, however it hangs for a long time if the controller is not on the network. For this reason I thought it would be good to use the Reachability.cs class which can be found here:
https://github.com/xamarin/monotouch-samples/blob/master/ReachabilitySample/reachability.cs
Instead of using google.com as the host, I am using the IP address of the controller. I have read that there is a bug with this class which causes it to not like having "http" at the beginning of the URL. Having now tried numerous things to get this working I am out of ideas.
Do anyone have any suggestions? Perhaps I am reinventing the wheel here.
Having now tried numerous things to get this working I am out of ideas.
From your question it's not clear what issue you're having with the Reachability class. Maybe you could edit it and add more details ? e.g. what you tried so far, how it reacts like: never works, throws/crash, inconsistent results ...
Do anyone have any suggestions?
If your main issue is blocking the UI of your application then you could (and should anyway) do your connection and data transfer asynchronously (or a separate thread) and once completed update your UI (from the main thread).
E.g. using WebClient.DownloadDataAsync
I need to find available network connections like eth,wlan,bluetooth. Does Qt emit any signals on detection of these access-points automatically? And also if more than 1 connection is available how would I know that which access point is used by system? And also if only 1 connection[apart form eth0] is present, for ex:WLAN Do we need to apply any additional settings for using ftp/htttp protocols?
Thanx
I think what you are looking for is QNetworkConfigurationManager which was added in Qt 4.7.
QNetworkConfigurationManager provides access to the network configurations known to the system and enables applications to detect the system capabilities (with regards to network sessions) at runtime.
It has signals for configurations being added and removed.
It can also trigger a scan with the updateConfigurations() slot (a signal will be emitted when complete):
Initiates an update of all configurations. This may be used to initiate WLAN scans or other time consuming updates which may be required to obtain the correct state for configurations.
You can set the connection a QNetworkAccessManager uses by calling QNetworkAccessManager::setConfiguration.