Could it be incompatible modem init or hangup strings? Is the computer reboot really required, cycling the TNC alone does not solve the problem. If so, verify that you have the handshaking correct. Also check dmesg once the serial port hangs up. Maybe something is logging a message. ----- Actually the TNC doesn't use any hang up or init strings such as the AT command set a Hayes compatible modem would use. When the port is opened and the TNC receives a '*' character it auto detects the baud rate and just starts talking. I will look into dmesg tonight and see if I can find anything. -brian Brian D. McGrew { brian@xxxxxxxxxxxxx || brian@xxxxxxxxxxxxxxxxxxx } --- > Those of you who think you know it all, really annoy those of us who do!