Sanyo VDC-HD3100/HD3100P - Manual (Page 58)

The clock time will not be adjusted if the difference between the set time and the current time
exceeds the range of -29 to +30 minutes.
If you set [CLOCK ADJUST] to “ALARM IN1”, the ALARM IN1 terminal will serve dedicatedly as a
time adjustment terminal, so you can see only the item [POLARITY] in [ALARM IN1] on the ALARM
SETTINGS screen.
Working with Administrator Configuration Screens 10/50