Telex Integrated Signal Processor ISP-100 - Manual (Page 21)

2-7
Setup & Installation
Figure 2-13 RFI choke data.
RFI choke such as Steward PN: 28B2025-0A0 should be used
at the ISP-100 end of the cable. See Figures 2-13 and 2-16, and
Table 2-1 for more information.
Rear Panel RS-232
Figure 2-14 RJ-45 to DB-25. Figure 2-15 RJ-45 to DB-9.
The serial port selector switch should be set in the up position. If
the PC’s COM port is a DB-25 connector, wire the cable
according to Figure 2-14. If the PC’s COM port is a DB-9
connector, wire the cable according to Figure 2-15. No RFI
choke is needed. See Figure 2-16 and Table 2-1 for more
information.
Connections Over 50 Feet
The EIA specifications for RS-232 communications allow for
connections up to 50 feet. For longer connections, the RS-232
signals must be converted to a standard, such as RS-485, that is
tolerant of long distances. The converter on the PC end of the
connection can be PC powered, but the converter at the ISP-100
end of the connection must have its own power supply. Before
buying converters please contact TELEX Communications, Inc.
for an application note on this topic.
Not using an RFI
choke while using the
front panel serial port
could cause increased
interference with other
devices and void the
FCC compliance.
RS-232 cable runs
over 50 feet could
cause unreliable
communications. It is
better to use RS-485
converters for
connections over 50
feet. Be sure to read
the application note on
this topic before
buying converters.