Hi Lars

I know your problem. Each Ping-pong of ACK will cost you approx. 1 second. If you hav small packages, this will be an awful lot of time. On the other hand, if you have large packages, the retransmission of bad packages will take too much time.

The suloution is a sliding-window type of protocoll. I've used Zmodem with great success in such an application.

/Fredrik