Equinox Systems MEGAPORT Hardware Reference Manual page 46

To assist in the wiring of the MEGAPORT board, Equinox sells a
complete set of cabling accessories. See an Equinox Ordering Guide
for more information.
As shown in Figure 4-1, standard RS-232 devices may be connected to
LD ports and operate reliably at 38.4 Kbps over standard two-twisted-
pair cable at distances up to 1000 feet without requiring a line driver
on the terminal end.
If an Equinox LDA-232 terminal powered line driver is used at the
terminal end the distance is increased to 3000 feet. The LDA-232 also
provides surge suppression on the terminal end.
Even greater distances can be achieved at lower bit rates. At 19.2
Kbps both distances double and at 9600 bps they double again.
However, special care must be taken in connecting devices to LD
ports to obtain these distances.
Complete details about LD ports may be found in Equinox Technical
Note #1, Equinox part number 302024, a copy of which is enclosed
with all MEGAPORT LD boards.
40
1000 feet at 38.4 Kbps
without line driver
3000 feet at 38.4 Kbps
with LDA-232 at terminal end
Figure 4-1. LD Port application.
Equinox MEGAPORT Hardware Reference Manual