To the DNC software, it's the same whether you're drip-feeding or downloading to CNC memory. Basically, the DNC software should begin sending when "triggered", and it should handshake using Xon/Xoff or RTS/CTS until the program is sent. Normally, the DNC software does not know if you are downloading or drip-feeding.

Sounds to me like you're pressing CYCLE START on the machine before the DNC software is ready to send. On most CNCs, you go to DNC mode, then press CYCLE START. At that point, the CNC will send an Xon code to the DNC system, which should begin sending data. If you press CYCLE START on the machine first, then go to the DNC side and send the file, the DNC software may still be waiting for the Xon, but the CNC has already sent it. Be sure to get the DNC system ready to send first, THEN press CYCLE START.

I don't know about Predator because we sell PC-DNC Editor and PC-DNC Plus. The priciple should be the same, however.