Introduction1-73610-A2-GB91-90 July 1999The asynchronous word size supported with theSingle-Port Async/Sync feature is 6 to 10 bits, excludingstop and start bits, for a maximum allowable charactersize of 12 bits. In addition, the DSU is V.14 compatible sothe DSU port can run overspeed or underspeed by thepercentage specified by the V.14 requirements. Table 1-3provides these percentages. For example, if the charactersize is 10, the maximum overspeed allowed for thetransmitter is 1.023 times ( x) the asynchronous rate.Multipoint ConfigurationWhen operating with the Async→Sync configurationoption enabled, a single-port multipoint circuit canoperate using nondisruptive diagnostics, similar to asingle-port point-to-point configuration. Figure 1-2illustrates this configuration. Note that both the controland tributary DSUs have single-port async/sync capabilityand are configured the same, with the same rate set forboth the DSU and DTE ports. Refer to Table 1-2 todetermine the maximum diagnostic rate that can be runfor various single-port async/sync configurations, andTable 1-3 to determine the overspeed or underspeedpercentage at which the DSU port can operate.Table 1-3V.14 DTE Overspeed/Underspeed PercentagesCharacter Size % Over/Underspeed8 3.18 –2.59 2.79 –2.510 2.310 –2.511 2.111 –2.512 2.012 –2.5Figure 1-2. Single-Port Multipoint Circuit with Nondisruptive Diagnostics
