Nortel NT1R20 Description page 108

Page 84 of 290 NT5D11 Line-side T1 Interface Card
553-3001-105 Standard 5.00 June 1999
Sanity timer
The line-side T1 card also contains a sanity timer that resets the
microcontroller in the event of a loss of program control. If the timer is not
properly serviced by the microcontroller, it times out and causes the
microcontroller to be hardware reset. If the microcontroller loses control and
fails to service the sanity timer at least once per second, the sanity timer will
automatically reset the microcontroller, restoring program control.
Man-Machine Interface (MMI)
The line-side T1 card provides an optional man-machine interface that is
primarily used for T1 link performance monitoring and problem diagnosis.
The MMI provides alarm notification, T1 link performance reporting and
fault isolation testing. The interface is accessed through connections from the
I/O panel to a terminal or modem. Multiple cards (up to 64) can be served
through one MMI terminal or modem by cabling the cards together.
The MMI is an optional feature since all T1 configuration settings are
performed through dip switch settings or preconfigured factory default
settings. The man-machine interface is discussed fully in "Man-Machine T1
maintenance interface software" on page 109.