See the documentation at:
DTC3231 Library Documentation
Where there is the section on alarm bits and setting alarms:
// Alarm functions
void getA1Time(byte& A1Day, byte& A1Hour, byte& A1Minute, byte& A1Second, byte& AlarmBits, bool& A1Dy, bool& A1h12, bool& A1PM);
/* Retrieves everything you could want to know about alarm
* one.
* A1Dy true makes the alarm go on A1Day = Day of Week,
* A1Dy false makes the alarm go on A1Day = Date of month.
*
* byte AlarmBits sets the behavior of the alarms:
* Dy A1M4 A1M3 A1M2 A1M1 Rate
* X 1 1 1 1 Once per second
* X 1 1 1 0 Alarm when seconds match
* X 1 1 0 0 Alarm when min, sec match
* X 1 0 0 0 Alarm when hour, min, sec match
* 0 0 0 0 0 Alarm when date, h, m, s match
* 1 0 0 0 0 Alarm when DoW, h, m, s match
*
* Dy A2M4 A2M3 A2M2 Rate
* X 1 1 1 Once per minute (at seconds = 00)
* X 1 1 0 Alarm when minutes match
* X 1 0 0 Alarm when hours and minutes match
* 0 0 0 0 Alarm when date, hour, min match
* 1 0 0 0 Alarm when DoW, hour, min match
*/
void getA2Time(byte& A2Day, byte& A2Hour, byte& A2Minute, byte& AlarmBits, bool& A2Dy, bool& A2h12, bool& A2PM);
// Same as getA1Time();, but A2 only goes on seconds == 00.
void setA1Time(byte A1Day, byte A1Hour, byte A1Minute, byte A1Second, byte AlarmBits, bool A1Dy, bool A1h12, bool A1PM);
// Set the details for Alarm 1
void setA2Time(byte A2Day, byte A2Hour, byte A2Minute, byte AlarmBits, bool A2Dy, bool A2h12, bool A2PM);
// Set the details for Alarm 2
void turnOnAlarm(byte Alarm);
// Enables alarm 1 or 2 and the external interrupt pin.
// If Alarm != 1, it assumes Alarm == 2.
void turnOffAlarm(byte Alarm);
// Disables alarm 1 or 2 (default is 2 if Alarm != 1);
// and leaves the interrupt pin alone.
bool checkAlarmEnabled(byte Alarm);
// Returns T/F to indicate whether the requested alarm is
// enabled. Defaults to 2 if Alarm != 1.
bool checkIfAlarm(byte Alarm);
// Checks whether the indicated alarm (1 or 2, 2 default);
// has been activated.
