Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
In a multipoint configuration including a primary modem and numerous secondary modems, the secondary modems cannot provide the key information that the line is open if the stations are not polled by the data link control of the primary modem. The solution is the use of an alarm tone sent by a beaconing modem. For this, the last modem on the line is set up to transmit a "bip" at regular time intervals, for instance, every 15 seconds. If no "bip" is detected while such a time interval has elapsed, the primary modem outputs an alarm status. Any modem can be selected as a beaconing modem, and in particular the modems corresponding to the inactive stations or the vital nodes.