TOTAL ACCESS 1500 REM TERM SYS CONTROL UNIT The ADTRAN Total Access 1500 System Controller Unit (SCU) is a common module plug-in unit that provides all control functions for the Total Access 1500 common units and all individual access modules. It is the logical and physical interface to the Total Access 1500 and is responsible for managing the craft interface port for provisioning of channel units. The SCU manages all network related functions and communicates externally through RS-232, RS-485, and Ethernet interfaces. The SCU monitors the T1 alarm information received from the LIU along with the status of the PSU/RG, and then determines the alarm state of the bank.