'Set DDA mode'

def _DDA(self, seekTo, slaveDelta, speed=False, waitArrival=True):

    if (not speed):
        speed = self.speed
    if (((seekTo <= self.limit) or (self.limit == 0)) and (seekTo >= 0) and (seekTo <= 65535) and (slaveDelta >= 0) and (slaveDelta <= 65535) and (speed >= 0) and (speed <= 255)):
        (masterPosMSB, masterPosLSB) = _int2bytes(seekTo)
        (slaveDeltaMSB, slaveDeltaLSB) = _int2bytes(slaveDelta)
        p = snap.Packet(self.address, snap.localAddress, 0, 1, [CMD_DDA, int(speed), masterPosMSB, masterPosLSB, slaveDeltaMSB, slaveDeltaLSB])
        p.send()
        if waitArrival:
            notif = p.getReply()
            if (not (notif.dataBytes[0] == CMD_DDA)):
                raise _RepRapError('Expected    DDA    notification')
