code: def send_command(
          self, command, callback=True, command_type=QRTPacketType.PacketCommand
      ):
          
          if self.transport is not None:
              cmd_length = len(command)
              LOG.debug("S: %s", command)
              self.transport.write(
                  struct.pack(
                      RTCommand % cmd_length,
                      RTheader.size + cmd_length + 1,
                      command_type.value,
                      command.encode(),
                      b"\0",
                  )
              )
  
              future = self.loop.create_future()
              if callback:
                  self.request_queue.append(future)
              else:
                  future.set_result(None)
              return future
  
          raise QRTCommandException("Not connected!")
docs: Sends commands to QTM