Hardwired Connections; Point-To-Point Decision Tree - HP 262SA Reference Manual

Data Communications
Having selected point-to-point you must now make the series of decisions illustrated in figure
7-2. As indicated in the figure, point-to-point configurations always operate in asynchronous
mode.
Point-to-Point
(Asynchronous)
Hardwired
(Full Duplex)
Modem
(Full Duplex)
Figure 7-2. Point-to-Point Decision Tree
For each desired point-to-point data link you must decide whether you want a hardwired or
modem connection.
A hardwired connection, where feasible, is the cheaper alternative because it eliminates the
use of modems and common carrier (telephone company) lines.
A major consideration in selecting which type of connection to use is the anticipated distance
between the terminal and the computer. If the terminal will be located in the vicinity of the
computer system you may use a hardwired connection. RS-232-C specifications limit cable
lengths to a maximum of 50 feet (15 meters); RS-422 specifies cable lengths from 200 to 4,000
feet (60 to 1,220 meters).
Another consideration is the desired availability of the particular computer port. If you wish to
have it available (at different times) to terminals in diverse and/or varying locations, then you
should choose a modem connection with dial-up capability.
Hardwired Connections
Ifyou have chosen a point-to-point hardwired connection, all that remains is to select the cable.
The available cables are covered later.
7-5