
Appendix A Serial Port Information
PCI Serial for Windows Me/9x A-4 ni.com
Figure A-1.  Typical Full-Duplex System
Half DuplexA typical half-duplex multidrop bus architecture also involves a 
master-slave protocol. However, in a half-duplex system, all transmitters 
and receivers are connected to the same transmission line. A half-duplex 
system is often referred to as a two-wire system. FigureA-2 shows a typical 
half-duplex system.
Figure A-2.  Typical Half-Duplex System
MASTER
Slave 1 Slave 2 Slave n
Tx
Tx Rx Tx Rx Tx Rx
Rx
MASTER
Slave 1 Slave 2 Slave n
Tx
Tx Rx Rx
Tx Rx
Tx
Rx