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Half Duplex mode in Qt



  • Hi there,
    I've written a mini program with Qt.5.12.0 to send data to a RFID reader/writer and then read the data using the QSerialPort class. Regardless of the data I send, I always get the same response back (Hex: \xFE). I've tested the RFID reader/writer with RealTerm and the same thing happens. However, when I select the "Half Duplex" mode in RealTerm, I get the correct response back. So my question is, how can I select a "Half Duplex" mode in the QSerialPort class? EvanZ



  • Can you post information about protocol and device?
    Is it a 485 device?



  • Hi MrDebug, Thank you for your reply. I don't know if it is a 485 device, but I know that it works with ISO 14443A/B, ISO 15693, Mifare Desfire and Mifare Plus cards. EvanZ


  • Lifetime Qt Champion

    @EvanZ

    @mrdebug said in Half Duplex mode in Qt:

    Can you post information about protocol and device?

    Is there no documentation for your device?



  • Sorry but the ISO 14443A/B, ISO 15693 is the standard mifare "radio size".
    It could implement the nfc standard.



  • I'm working with two different RFID reader/writer devices. One is a CL 663 and the other one, I don't have any documentation, unfortunately. But I have the same problem with both types of devices.


  • Lifetime Qt Champion

    Hi,

    @kuzulis do you have any insight about this use case ?



  • AFAIK, the serial port device always work in full-duplex. A half/full duplex makes not sense for RS232/TTL interfaces. It makes sense only for RS485/422 interfaces.

    As I understand, RFID just echoing each command. Maybe it is possible to disable this default RFID behavior by sending some commands to RFID (see datasheet on yor RFID).

    About the RealTerm and its "Half-Duplex" mode: I don't see any specific options to control the serial port handle there (in those Deplhi sources) to enable the "Half-Duplex" mode. I assume, that this mode are implemented in the programmatically way (it just ignores the received echo).


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