emc unity 400 configure snapshot schedules every 48 hours

As Rainer says UEMCLI gives alot more config options for snaps than the GUI.  Try these as an example of creating a snap every 2 days at 8pm and keeping it for 7 days:

PS C:\Users\Administrator> uemcli -d 1.1.1.1 -u admin -p mypassword /sys/task/rule create -schedName 48hours -type daysinterval -every 2 -at 20:00 -keepFor 7d

Storage system address: 1.1.1.1

Storage system port: 443

HTTPS connection

ID = SchedRule_304

Schedule ID = snapSch_18

Operation completed successfully.

PS C:\Users\Administrator> uemcli -d 1.1.1.1 -u admin -p mypassword /sys/task/rule -id SchedRule_304 show

Storage system address: 1.1.1.1

Storage system port: 443

HTTPS connection

1:    ID                = SchedRule_304

      Type              = DaysInterval

      Frequency         = Every 2d at 20:00

      Keep for          = 7d

      Allow auto-delete = no

      Access            = Checkpoint