It sets the maximum number of Link-Check “probes” retransmission.

If this counter runs over, it means “N2” Link-Check “probes” have been sent without receiving any acknowledge, the P-Link or S-Link channel are declared out of service.

In the case it occurs on the P-Link channel, the communication will be activated on the S-Link channel, providing that it's properly configured.

In the case it occurs with the S-Link channel, the connection is closed with the code 80 90 80 8B; if it happens three times consecutively the port will be placed in the “STOPPED2” state, without being able to receive or make further calls.

To recover from the error it's necessary to execute the init res: command. If alarm detection was enabled, i.e. if LOG is set with the “A” option, it's also possible to recover from the error with the alarm reset command or using the analogous menu available on the LCD display of the front panel. If the communication cannot go on any longer either on P-Link or S-Link, the upper level driver will be advised on the error and point out a “Level 1 Down”.