Gurux Serial Android (java) not connect using Standard Com Port (CP210x UART Bridge)

//implementation("org.gurux:gurux.serial.android:2.0.2") and UsbInterface usbIf = it.getValue().getInterface(1); work :-)))

but another problem with sending any data.

when UsbInterface usbIf = it.getValue().getInterface(0); data send and receive normal

when UsbInterface usbIf = it.getValue().getInterface(1); always (ret = mConnection.bulkTransfer(mOut, buff, pos, dataSize, mWriteTimeout);) ret=-1 and execute throw new IllegalArgumentException("Data send failed.");

in this method:
public final void send(final Object data) throws Exception {
if (mOut == null) {
throw new RuntimeException("Serial port is not open.");
}
if (mTrace == TraceLevel.VERBOSE) {
notifyTrace(new TraceEventArgs(TraceTypes.SENT, data));
}
// Reset last position if end of packet is used.
mSyncBase.resetLastPosition();
byte[] buff = GXSynchronousMediaBase.getAsByteArray(data);
if (buff == null) {
throw new IllegalArgumentException("Data send failed. Invalid data.");
}
int ret, pos = 0, dataSize = mOut.getMaxPacketSize();
while (pos != buff.length) {
if (buff.length - pos < dataSize) {
dataSize = buff.length - pos;
}
ret = mConnection.bulkTransfer(mOut, buff, pos, dataSize, mWriteTimeout);
if (ret != dataSize) {
throw new IllegalArgumentException("Data send failed.");
}
pos += ret;
}
this.mBytesSend += buff.length;
}

Why?

Good evening.

My test project:
class MainActivity : AppCompatActivity(), IGXMediaListener {
private lateinit var binding: ActivityMainBinding
var log = ""
var receivedString = ""

override fun onCreate(savedInstanceState: Bundle?) {
var serial : GXSerial

super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)

serial = GXSerial(this)
serial.addListener(this)

binding.buttonConnect.setOnClickListener {
try {
serial.port = serial.ports[1]
serial.baudRate = BaudRate.BAUD_RATE_9600
serial.dataBits = 8
serial.parity = Parity.EVEN
serial.stopBits = StopBits.ONE
serial.open()
}
catch (ex: Exception) {
updateLog(ex.toString())
}
}

binding.buttonSend.setOnClickListener {
try {
if(serial.isOpen){
val cmd = "<pswd=tex addr=local cmd=set ch=0 crc=x>"
serial.send(cmd)
updateLog(cmd)
}
}
catch (ex: Exception) {
updateLog(ex.toString())
}
}
}

Android manifest have:
...
<uses-permission android:name="android.hardware.usb.host" />
<uses-permission android:name="android.permission.USB_PERMISSION" />

settings.gradle:
...
rootProject.name = "Test"
include(":app")
include(":Serial")

build.gradle:
...
implementation(project(":Serial"))
implementation("org.gurux:Gurux.Common.Android:2.0.1")

if in GXSerial.java in function open():
UsbInterface usbIf = it.getValue().getInterface(0); - all works normal:
22:07:35: onPropertyChanged: PortName
22:07:35: onPropertyChanged: Parity
22:07:35: MediaStateChange: OPEN
22:07:39: <pswd=tex addr=local cmd=set ch=0 crc=x>
22:07:39: <r=0 addr=local ch=0>

but i need use another interface by usb port:
UsbInterface usbIf = it.getValue().getInterface(1); - and after send several messages throw exception:
22:12:38: onPropertyChanged: PortName
22:12:38: onPropertyChanged: Parity
22:12:38: MediaStateChange: OPEN
22:12:39: <pswd=tex addr=local cmd=set ch=0 crc=x>
22:12:41: <pswd=tex addr=local cmd=set ch=0 crc=x>
22:12:43: <pswd=tex addr=local cmd=set ch=0 crc=x>
22:12:50: java.lang.IllegalArgumentException: Data send failed.

What am I doing wrong? Maybe the USB has not been granted permissions? I've been trying to solve the problem for 4 days. This afternoon, we somehow managed to transmit and receive data, but without changing anything in the code, it stopped working.

Good afternoon.
Yes, I certainly tried with the serial android example app. When connecting the device, 2 ports with the same name are available: CP210x UART Bridge.
When selecting ANY of the ports, sending is ALWAYS carried out via the Enhanced COM PORT, which in USB is with the index 0. This is hardcoded in the line: UsbInterface usbIf = it.getValue().getInterface(0); (GXSerial.java, line 768).
When changing the code, the Standard COM PORT interface would be used: UsbInterface usbIf = it.getValue().getInterface(1); the serial android example app also has the error "Data send failed."

Here is an image that shows that the null interface is always selected, regardless of the selected port.

Hi.
I use api 28-32.
Documentation by this Link:
https://drive.google.com/file/d/1oHbFcsjs7Mvby9MB13HDTy7N8wQD7-lH/view?…
When use interface 1 (standart com port) all work.