Pseudo Cd; V.13 - ZyXEL Communications U-90E User Manual

8.3.1 Pseudo CD

Set s12.7 to 1 can enable this function. When s12.7 is set, CD (Carrier Detect) signal
will light up only when there is received data present. This function is often used
together with RTS option set to &R0. (CTS track RTS). Please take note that it would
drop the line when CD signal is on for more than 20 second unless s12.6 is set to 1.

8.3.2 V.13

Set s44.5 to 1 can enable this function. The communication software packages written
for half-duplex mode rely on RTS, CTS and CD signals. The V.13 protocol is provided
where the local CD follows the remote modem's RTS signal.
Synchronous Mode Operation
U-90E Data/Fax Modem
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