EASession stream function doesn't fire

I have MFi device(RFID reader) and I'm trying to catch scanned tags in my app.

So I use EAAccessorymanager to get the shared accessory and read data from it.

When I open session and scan tags, stream function does not fire and I can't understand what I'm doing wrong.

import Foundation
import ExternalAccessory
class RFID: NSObject, EAAccessoryDelegate, StreamDelegate
{
  var _accessory: EAAccessory! 
  var _session: EASession! 
  var _protocolString: String?   
  func ******() { 
     let manager = EAAccessoryManager.shared() 
     let accessories = manager.connectedAccessories 
     if (accessories.count > 0) 
     { 
        _accessory = accessories[0];  
        _session = EASession(accessory: _accessory, forProtocol: _accessory.protocolStrings[0]);  
        _accessory.delegate = self; 
        _session?.inputStream?.delegate = self; 
        _session?.inputStream?.schedule(in: .current, forMode: .default); 
        _session?.inputStream?.open();
        print(_accessory); 
        print(_session); 
     } 
  }  
  func stream(_ aStream: Stream, handle eventCode: Stream.Event) { 
     switch eventCode { 
          case Stream.Event.openCompleted: 
               break 
          case Stream.Event.hasBytesAvailable: 
               // Read Data
               print("Data Available"); 
               break 
          case Stream.Event.hasSpaceAvailable: 
               // Write Data 
               break 
          case Stream.Event.errorOccurred: 
               break 
          case Stream.Event.endEncountered: 
               break  
          default: break 
     } 
  } 
}

NOTE: printed accessory is always the right one and inputStream is not nil!