Dedicated EIA RS-232 Networks 2-5
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SWITCH (OR CUSTOMER) REQUIREMENTS FOR
DEDICATED RS-232
If the distance between systems is greater than 10 feet (3.05 meters), an M25A RS-232 extender cable
(male-female) is required in addition to the H600-331, Group 2 cable and H600-330, Group 1 null-modems
at each AUDIX system. Only one null-modem is required in each link. The extender cable is inserted on
one side of the null-modem. See Figure 2-5, Dedicated RS-232 Extended Connections. This cable comes
in lengths up to 50 feet (15.24 meters).
If the distance between AUDIX systems is greater than 50 feet, you can do one of two things:
• In addition to the H600-331, Group 2 cable at each AUDIX system, a pair of data sets must be inserted
in place of the null-modem (see Figure 2-5). The data sets must be Z3A Asynchronous Data Units
(ADU). The following equipment is required (see Figure 8-3). Two Z3A Asynchronous Data Units
(ADU), two D8W-87 modular cords, two 103A adapters, one D8AM-87 crossover cord, external power
on one end (400B adapter, D6AP-87 modular cord, 248B adapter, and a Model 2012D transformer),
and building wire (4-wire).
Check the document(s) shipped with the data sets for the maximum distances allowed.
• The dedicated connection can be recabled as a switched connection. See Chapter 3, Switched EIA
RS-232 Networks.
DATA RATES FOR DEDICATED RS-232
Data rate limitations are imposed on the RS-232 interface when certain distances are exceeded:
• At 20 feet (6.1 meters) or less, the data rate can be as high as 64 Kbps.
• At 20 to 50 feet (6.1 to 15.25 meters), the maximum data rate is 19.2 Kbps unless limited-distance
modems are used. Check with the documentation shipped with the limited-distance modems.
• At more than 50 feet (15.25 meters), limited-distance modems must be used. Check with the
documentation shipped with the limited-distance modems.
NOTE
Configurations with limited-distance modems are supported only as custom work.
