[Rxtx] loopback puzzle
Bob_Jacobsen at lbl.gov
Wed Sep 6 09:37:49 MDT 2006
At 10:49 AM -0400 9/6/06, Dr. Stephen Judd wrote:
>I used all the options available, and all had the same effect.
>I stuck in a loop that ran through the ports enumerated by
>and there are only 2 of them: /dev/cu.modem and /dev/tty.modem
>both of which are of "type 1" and have no "owner".
>The way you phrase your question leads me to believe there is
>something notoriously obvious about cu.modem, but Google is not
>making anything obvious for me. Please explain.
At first, the modem is probably in a "command mode", where it's
echoing back the characters it sees. This dates back to the original
Hayes modems, where you could type commands to tell it to dial, etc.
Once the connection is made, it goes to "data mode", where it's just
passing the characters through.
Bob Jacobsen, UC Berkeley
jacobsen at berkeley.edu +1-510-486-7355 fax +1-510-643-8497 AIM, Skype JacobsenRG
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