DT Etherlink IV User Manual- 26 - CONTRA (contradirectional): Transmit clock and transmit data have opposite directions, i.e.transmit clock is an output from the modem at signal number 114 and transmit data is an inputto the modem at signal number 103.In combination with the command SETCLOCK (units with Nx64 interface have the possibility to setthe clock source to the SHDSL line side as Nx64 clock (parameter “V35” of SETCLOCKcommand)), it is possible to realise different clock schemes. The following table shows differentvalid combinations of clock modes for the Master modem:Command: EXTCLOCK SETCLOCKArgument: SRC DIRModes: DTEClock ModeDCEClock ModeDCEClock DirectionxDSLClock ModeDSLpayload Nx64 only,Nx64 * & WANSlave internal don’t care internalMaster external codirectional Nx64E1 & Nx64E1 & Nx64 & WAN Slave DSL don’t care E1The following table shows different valid combinations of clock modes for Slave modem:Command: EXTCLOCK SETCLOCKArgument: SRC DIRModes: DTEClock ModeDCEClock ModeDCEClock DirectionxDSLClock ModeDSLpayload Nx64 only,Nx64 * & WAN Slave DSL don’t care Nx64E1 & Nx64E1 & Nx64 & WAN Slave DSL don’t care E1Interface V35-1:V35Extrate : 128Autoloop : ONExtclock : TTC/COInterface V35-1:V35Extrate : 128Autoloop : OFFExtclock : NORMAL/CONTRAFigure 3.13. Application Example V.35 with external clock master104115113103105108106107109codirectional contradirectional103114115104105108106107109DTE SHDSL MODEMNx64Nx64DCE DCEClock External Clock RemoteMASTER SLAVESHDSL MODEM DTE
