Not receiving data after connection

[Ngandu]

Hey

After connecting successfully, I am not receiving data from the serialport.
Is there an additional step required after connecting?

This is my connection :

SerialPortAPI.setSuPath("/system/xbin/su");
const serialPort = await SerialPortAPI.open("/dev/ttyS4", { baudRate: 115200, dataBits:16 });

[lagschwein]

Are you subscribing to the onReceived event like this:

  // subscribe received data
  const sub = serialPort.onReceived(buff => {
    console.log(buff.toString('hex').toUpperCase());
  })

[Ngandu]

Hey @lagschwein
Yes, I am subscribing.

I am working on an RFID Reader, and when the scan/reading is triggered I am not receiving the data.

[lagschwein]

I would need a bit more information about your code to diagnose the problem

[Ngandu]

const serialPort = useRef();

async function connect() {
    try {
      SerialPortAPI.setSuPath("/system/xbin/su");
      serialPort.current = await SerialPortAPI.open("/dev/ttyS4", { baudRate: 115200 });

      // subscribe received data
      serialPort.current.onReceived(buff => {

        let trmp = buff.toString('hex').toUpperCase();

        console.log(trmp);
      })


    } catch (error) {
      console.warn(error);
    }
  }

  async function disconnect(){

            serialPort.current.close();

  }

async function send(hex){
    // send data with hex format
    try {

     await serialPort.current.send(hex);

    } catch (error) {
      console.warn(error);
    }
  }

Hey @lagschwein
Above is the code.

I use UseRef to keep the state of the connection and have separated the closing and sending through of data.

I know that connection works because I don't get any error when I send data after connecting.

[lagschwein]

Does it work when sending data?

Also are you calling devicePathsAsync() to determine whether /dev/ttys4 is correct serial port path?

[Ngandu]

I think it does cause it does not return any error.
that is after connecting, if I try sending data before connecting I get an error

And yes, the device path is just a check, which works as well.

[lagschwein]

Does it work when sending data?

Also are you calling devicePathsAsync() to determine whether /dev/ttys4 is correct serial port path?

When I ask does it work I mean are you actually receiving the serial data on the other end of the serial port?

[Ngandu]

Once I connect I can get the device paths, so I am guessing the connection is correct.
But the issue is when I trigger scanning on the device I don't receive any data.

[lagschwein]

I would suggest switching to using https://github.com/bastengao/react-native-usb-serialport-for-android. I have been having much more success with this module.

[Ngandu]

Thank you @lagschwein
I will try it and give feedback

[lagschwein]

@Ngandu Depending on your implementation you may need to do some node module patching. There is an issue on that same repo that I replied to with a good solution here.