Way to check for input data from serial port without polling in main

[Kammersgaard]

Hey!

I'm trying to make a class in Qt to handle communication with a turnable button with programable resistens. The button came with some functions for communicating with it. I can communicate with it just fine. Every time it is turn it sends a report to the serial port it's connected to. Untill now I've just been polling a function that came with the device for reading these reports. Now I was wondering if I somehow could check for input outside the main loop. Then when there's input call this function to read it.

I've tried solving this problem by overwriting the winEventFilter but I only see when the device is plugged-in or removed. No event goes through here when the device sends a report. Is there a good reason for this?
Then I found something about SerialPort::DataReceived Event but this seem only to be useful if I myself had initialized the port and not through the function I got with the device. Am I wrong?

Hope someone got a good advice on how to solve this!

[kuzulis]

Use ready-made library as QtSerialPort or QextSerialPort and use the signal is readyRead().

I would suggest taking QtSerialPort (http://qt-project.org/wiki/QtSerialPort)

[hezbon]

Use ready-made library as QtSerialPort or QextSerialPort and use the signal is readyRead().

I would suggest taking QtSerialPort (http://qt-project.org/wiki/QtSerialPort)

i suggest this same solution and use the readyRead to fire up a slot function in your class

[Kammersgaard]

I've been trying to install the library by following the instructions in the link you gave. I've not tried running qt projects in the command propt before so it might be a simple mistake from my side. I get this:

SerialPortd_resource.rc(4):fatal error RC1015: cannot open include file 'winver.h'

I think maybe I have to include something in my path but I don't know what.

[ChrisW67]

You need to be using a command prompt with both the Qt build and Microsoft compiler environments established. If you are using the Qt SDK then you can get a Qt Command Prompt using the option in your Start Menu. Then you need the Microsoft environment: http://msdn.microsoft.com/en-us/library/f35ctcxw.aspx

[Kammersgaard]

I've now tried openning the serialport.pro in Qt and then ran it there. A window open saying "Press <Return> to close this window". The window was named C:\QtSDK\QtCreator\bin\qtcreator_process_stub.exe. Does this mean that the library was installed?

I then tried running my project but it didn't compile saying:
main.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall QtAddOn::SerialPort::SerialPort::~SerialPort(void)" (__imp_??1SerialPort@0QtAddOn@@UAE@XZ)
main.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) public: __thiscall QtAddOn::SerialPort::SerialPort::SerialPort(class QObject *)" (__imp_??0SerialPort@0QtAddOn@@QAE@PAVQObject@@@Z)
release\test2.exe : fatal error LNK1120: 2 unresolved externals

It seems I need to include some library related to SerialPort

Added after 34 minutes:

Thanks. Ran it in the command prompt for MSVC and it worked! I also got a qt project where a SerialPort is initialized to work. But only the debug version. No release was installed. Tried writing CONFIG += release as the guide says but it just says Cannot find file: CONFIG Cannot find file: release.

Besides that I need some documentation. Can't find it on the internet. Something about qdoc but don't know what that means exactly..

[kuzulis]

Tried writing CONFIG += release as the guide says but it just says Cannot find file: CONFIG Cannot find file: release.
Oops.. Sorry.. My mistake.
Should be written without spaces:


CONFIG+=release

I'll correct the WiKi.

[Kammersgaard]

Thanks that worked but now it says cannot open input file 'SerialPort.lib'. I emptied the build folder before running it. Should I remove anything else?

[kuzulis]

Can't find it on the internet. Something about qdoc but don't know what that means exactly..
The documentation is not finished yet, but you can use, need build:
1. Check in installed Qt for file <path to qt directory>\doc\html\qt.index
2. Set path to Qt directory:


set QT5DOC=<path to qt directory>

3. Make QDoc, example:


qdoc3 <path to serialport source>\doc\serialport.qdocconf

4. The result will appear the documentation in:


<path to serialport source>\doc\html\



Thanks that worked but now it says cannot open input file 'SerialPort.lib'. I emptied the build folder before running it. Should I remove anything else?
Before assembling the Release should be completely clean build directory, and then (after assembly) - install the library.
Then in the Qt /lib and /bin directory will contain both Debug and Release serial port.

Added after 39 minutes:

UPD:

Thanks that worked but now it says cannot open input file 'SerialPort.lib'.

To solve this problem there are 3 way:

1) Build Debug and Release in separate directories, for example:
serialport-release
serialport-debug
and then, after build, turn run "make install" for each target ( from serialport-release and serialport-debug )

2) After build and install Debug target, need delete /QtAddOnSerialPort directory from <qt path>\include, and next,
restart Command promt and build and install Release target.

3) Just comment out the build of examples and tests in serialport.pro:


SUBDIRS = src #examples tests

[Kammersgaard]

With path to qt directory do you mean something like C:\QtSDK\Desktop\Qt\4.8.1\msvc2008? I didn't find any doc folder there. Checked the entire computer and no qt.index file. The closest was qt-sdk.index.

With the release installation I first installed the debug. Then I emptied the "serialport-build" folder where I had build the debug. Then I moved ahead with the release installation. First ran the qmake. That went fine. Then during the nmake I got the "cannot open input file 'SerialPort.lib'" error. What did I do wrong?

Added after 7 minutes:

Got the release installed now.

[kuzulis]

With path to qt directory do you mean something like C:\QtSDK\Desktop\Qt\4.8.1\msvc2008?
Yes, something like that.


I didn't find any doc folder there. Checked the entire computer and no qt.index file. The closest was qt-sdk.index.
So you need to build the documentation will take the file qt.index from source Qt4.


What did I do wrong?
I wrote to you three ways to solve this problem.

Added after 9 minutes:

UPD: Try download documentation as html.zip here: http://www.freeupload.cn/download.php?file=56885

[Kammersgaard]

Got it all working now so thanks a lot for the help! Now I'm trying to run the program on another computer. Should I install the library again in the same way or is it possible to just copy some of the files that the first installation made? In that case where to?

[kuzulis]

Need copy to another computer necessary *.dll libraries Qt and QtSerialPort, put them in a folder with your *.exe file, provided that you work in Windows.
If you work in Linux - a little differently.

In any case - this topic is not relevant to this post. Look for a solution in Google.