Toshiba STRATA DK14 Installation And Maintenance Manual page 673

BRI Wire Type Recommendations
CAT3 or CAT5 wire is recommended for ISDN BRI customer-premises wiring. While the ISDN
BRI signal works for some distance over almost any wire that is suitable for analog voice service,
better wire enables longer runs. CAT5 provides better 100-ohm impedance matching (at little extra
cost) between the TBSU or RBSU/RBSS circuit and the station Terminal Equipment (TE-1).
Normally the CAT3 or CAT5 wiring does not have to be shielded when used for ISDN BRI
premises wiring. However, the RJ45 jacks on the TBSU and RBSU/RBSS BRI circuits are
shielded and provide a ground shield in the event that shielded modular plugs and cable are used.
If using shielded cable and plugs, cable runs should only be grounded at the DK TBSU
Note
and RBSU/RBSS, RJ45 jacks. To prevent ground loops, do not ground both ends of
shielded cable runs.
Figure 16-13 RBSU/RBSS Location of LEDs and Connector Locations
TBSU and RBSU/RBSS BRI Cable Jacks and Connectors
In the U.S., the standard connector for ISDN equipment is the eight-pin RJ jack. Patch cables have
eight-pole plugs at both ends. The same pinout applies to both ends of an ISDN cable, which is the
practice of the data world. This means that a flat untwisted cable with an RJ modular plug at both
ends will have the locking tab of the plug on one end, "up;" and on the other end, "down," as
shown in Figure 16-14.
This is the opposite of telephony "silver satin" cables which have locking tabs on both
Note
ends facing the same direction. Telephony cables cause the pins at either end to crossover
while data cables provide a straight through pin-to-pin connection between modular jacks.
Strata DK I&M 6/00
RBSU
BSY
TS
CKT2
LOS
FS
BSY
CKT1
TS
LOS
FS
RJ-45 8-pin (shielded)
Modular Connector
TB3 (FG)
Reset Switch
(resets RBSU Firmware)
RS-232C Connector
for Call-Data Monitor
2795
RBSU/RBSS and TBSU Interface Units
RBSS
BSY
CKT4
TS
LOS
FS
BSY
TS
CKT3
LOS
FS
4th Circuit
2nd Circuit
3rd Circuit
1st Circuit
TB1 and TB2 (PFT)
ISDN Interfaces
16-23