GE D25 User Manual page 76

D25
User's Manual
Communications Ports,
The 580-0933 type of serial XCOM is available only through special order.
!
It provides power for external communication devices, such as modems, from
the D25 internal power supply. This violates the isolation specifications of
Caution
the card, and can lead to two problems, if not accounted for:
580-0933
• an external surge of voltage, such as a lightning strike, can be passed from a
Special Order
modem into the D25 internal circuitry where damage may occur
Only
• inadvertent connection of power to the card's external 3-pin terminal block may
cause damage to the D25 power system
Difference The XCOM ports provide the same functionality as the IED Ports, with this
Between IED
difference:
and Serial
• XCOM ports run at a lower priority than the IED ports. It is therefore most
XCOM Ports
efficient to put the heaviest communication on the XCOM ports.
Note If you place the heaviest traffic on the IED ports, the higher priority IED ports
will often delay servicing of the XCOM ports.
Constant high-volume traffic on the IED ports can cause the XCOM ports to
lose data. By placing the lower traffic connections on the IED ports, you
ensure that XCOM ports always get serviced in a timely manner. Heavier
traffic on the XCOM ports will be interrupted only momentarily (and within
the buffering ability of the XCOM card) by small bursts on the higher priority
IED ports.
Connecting Three variations of Ethernet / 802.3 XCOM cards are available:
Ethernet
• 10BASE2 (obsolete and available as Special Order – see Product Bulletin
XCOM
PRBT-0252)
Interfaces
• 10BASE-FL
• 100FX and 10/100TX XCOM Card, two multimode ST fiber optic ports and
two RJ45 ports. See page 127 for details.
All have dual interfaces, labeled XCOM1 and XCOM2.
• Cable: "Thin" Coax RG-58
10BASE2 Card
Connections &
• Connection is BNC-type.
Indicators
• First and last units on coaxial cable need 50Ω termination
Note:
76
Continued
The 10BASE2 XCOM card has no LED indicators on its back panel.
This option is obsolete and available as Special Order – see Product
Bulletin PRBT-0252)
994-0081-3.00-21
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