The information in this article applies to:
SUMMARY
Many communications applications need ring detection. The documentation for
SetCommState() indicates that EV_RING should be the event to set for this
purpose. However, the EV_RING bit does not work as expected; the EV_RINGTE
(ring indicator trailing edge) event should be used for ring detection.
EV_RINGEV_RING is set when the ring indicator is detected high during Modem Status Register (MSR) interrupt processing. This is an absolute state, but since it is read only during MSR interrupt processing, it will almost always be zero. The only time it will not be zero is when the ring indicator is high and the MSR interrupt is triggered for some other reason, such as a change in the state of a line (CD, CTS, or DSR). Because of this, EV_RING has no real value for detecting a ring.EV_RINGTEEV_RINGTE is set when a ring is detected on the modem. The trailing edge of a ring indicator generates an MSR interrupt, which in turn sets the EV_RINGTE event. Use this event to detect a ring.Additional query words: 3.10 Win16 no32bit COMM SetCommState event
Keywords : kb16bitonly KrCommapi |
Last Reviewed: November 4, 1999 © 2000 Microsoft Corporation. All rights reserved. Terms of Use. |