how to i synchronize serial read and write without using thread?

[pooch]

I have replaced the while loops with if, but what i observe is the code will now never read the input register. It just skips that part. Also the readyRead signal is not fired at all when i send data using my virtual serial(realterm). I think i am confused between my own stuffs.
Ok, i'll explain the total motive of my project.
what i have to do is:
Write to serialport when buttons are clicked. Also write to serialport continuously every few seconds and receive their response, intrepret it and display in my gui. It seems like i dont get any response. or there's something else wrong. do my readyRead and timer signals interfere with each other?

[anda_skoa]

The condition is probably the wrong way around. Try

if(modbus_master.CheckBusy()) return;

if(modbus_master.CheckBusy()) return;

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Not sure why you need that at all, the class seems to be using an event driven I/O (QExtSerialPort) so there should be signals when it becomes read for whatever you are checking.

Cheers,
_

[pooch]

I remove that part completely, it just works fine. Thanks.