Problem solved in CH34x devices when trying to write

src/com/felhr/usbserial/CH34xSerialDevice.java

@@ -91,7 +91,8 @@ public class CH34xSerialDevice extends UsbSerialDevice
 					&& endpoint.getDirection() == UsbConstants.USB_DIR_IN)
 			{
 				inEndpoint = endpoint;
-			}else
+			}else if(endpoint.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK
+					&& endpoint.getDirection() == UsbConstants.USB_DIR_OUT)
 			{
 				outEndpoint = endpoint;
 			}