Appendix E. Dsu To Dsu Tail Circuit - ADTRAN DSU III AR User Manual

DSU to DSU Tail Circuit
Appendix E
MODEM TAIL CIRCUIT APPLICATION
A DDS Tail Circuit is a serial connection of two DDS circuits as
shown in Figure E-1 on page E-2. The two circuits are joined at the
DTE port interface of each DSU unit. A special tail circuit crossover
cable is required so that transmit line connects to the receive line on
the other DSU as well as the DTR, CTS, RTS, and CD signal lines
get matched appropriately. Figure E-2 on page E-3 details the
crossover cable wiring.
ADTRAN DSU/CSU units will operate in this configuration.
ADTRAN does not recommend the tail circuit mode due to the potential
for clock slippage and data loss when using this configuration. Moreover,
further problems can occur when each DDS circuit is using a different
master clock source and will require additional hardware called a tail cir-
cuit buffer to reduce the risk of data overruns and clock slips.
61202011L1-1 DSU III AR User Manual E-1