code: def send_rpc_async(self, conn_id, address, rpc_id, payload, timeout, callback):
          
  
          callback(conn_id, self.id, False, 'RPCs are not supported on this adapter', None, None)
docs: Asynchronously send an RPC to this IOTile device
  
          Args:
              conn_id (int): A unique identifier that will refer to this connection
              address (int): the addres of the tile that we wish to send the RPC to
              rpc_id (int): the 16-bit id of the RPC we want to call
              payload (bytearray): the payload of the command
              timeout (float): the number of seconds to wait for the RPC to execute
              callback (callable): A callback for when we have finished the RPC.  The callback will be called as"
                  callback(connection_id, adapter_id, success, failure_reason, status, payload)
                  'connection_id': the connection id
                  'adapter_id': this adapter's id
                  'success': a bool indicating whether we received a response to our attempted RPC
                  'failure_reason': a string with the reason for the failure if success == False
                  'status': the one byte status code returned for the RPC if success == True else None
                  'payload': a bytearray with the payload returned by RPC if success == True else None