Half Duplex
The schematic below is used to make a half duplex RS232 monitoring cable.
This cable is used for monitoring 2 devices communicating in half duplex
fashion, that is, one device would send data and the other device would
receive data. Both devices cannot transmit at the same time with half
duplex, if that happened the data would be unusable.
Advanced Serial Port Monitor can be used to
receive either ASCII or Hex half duplex data. Also Advanced
Serial Port Monitor can monitor 2 sets of half duplex communicating devices
(1 set in each window).
Full Duplex
The next cable is used for monitoring full duplex RS232 communication.
For devices that may transmit data at the same time, this cable is the one
to use. Advanced Serial Port Monitor can display
both sides of full duplex RS232 communication.