Hello, Om my VIA Epia EK8000 I can jumper RS232 ports ttyS1-ttyS3 (COM2-COM4...) for 5 Volts instead of 12V ( and -12V) signals. My Garmin GPS18 provides only TTL levels so perhaps performance is a bit better if I use a `5V` RS232 port? What do you think? Udo