Hi Alexander, Can you tell us how you came up with those device names? I think it'll be more like /dev/{cua,tty}[0-7], though that range might be different if you have any other com(4) devices.
PCI serial cards typically attach as puc(4), meaning com(4) devices should appear.. or pccom(4).. if you're using a release <= OpenBSD 4.3. Are you able to post a dmesg? -Brynet