Chapter 1. Introduction61200.129L1-1 TSU 120 User Manual 1 5Normal (CSU) TimingThe typical timing option arrangement is shown inFigure 1-8. The PBX is looped timed sending data tothe TSU 120 which is actually synchronous to thereceived data. The Network Interface (NI) is theactual source of all timings. This timing option is thesame as that typically used for CSUs. This is thepreferred mode for use with a PBX application.This timing mode works equally well when the PBX isthe source of timing. In that configuration the net-work would not be providing timing.DTEOSCSecondaryInterface(SI)(OPTION)NetworkInterface(NI)T1 XMITT1 Receive( D S 1 )Nx56/64DTE CLOCKDSXPBX(IO PB)PBXFigure 1-8Normal (CSU)The network interface and secondary interface clockingoptions are set by using the Network (NI) Configurationmenu options.
