Toshiba Strara CTX Series, Руководство по установке и обслуживанию, Страница: 158 / 290

ISDN Interfaces
5-10
Strata CTX I&M September 2002
When multiple TE-1 and TA devices are installed on a single RBSU/RBSS BRI circuit, the devices
must share, or contend for, that circuit’s two B-channels. That is to say, a maximum of two
simultaneous voice and/or data calls are allowed between both devices connected to the same BRI
circuit. The contention rule for the two BRI B-channels is first come, first serve.
Figure 5-7 RBSU/RBSS Interfaces between the S/T Reference Points
Capacity and Cabinet Slot Information
The RBSU/RBSS can be installed in any slot except in a slot that has been left vacant to provide
capacity for RPTU2 or RPTU. Each RBSU and/or RBSS contains two circuits and each circuit reduces
the system capacity by two station ports
and two Exchange lines (one port/line per B-channel).
Therefore, if the RBSU PCB is installed, the station port and Exchange line count will increment by
four ports and four lines at the RBSU cabinet slot.
If the RBSU/RBSS is installed, the station port and Exchange line count will increment by eight
station ports and eight lines at the RBSU/RBSS cabinet slot. RBSU and RBSS PCBs can be installed
in any combination so long as the number of RBSU PCBs is the same or greater than the number of
RBSS PCBs. See
“ISDN BRI Digital Station PCBs” on Page 1-25 for the maximum BRI circuits
allowed.
PS-1 Backup Power Option
The RBSU provides an optional backup power supply, R40S, that will supply backup power to TE
devices in the event of an AC power loss. This power backup option only applies to RBSU or RBSS
circuits that are configured in the NT mode. See
Figure 5-11 to install the R40S.
Also the Strata CTX system must have battery backup to allow the R40S power backup function to
operate. The R40S power supply is an ISDN, PS-1 type power unit which means it supplies power to
TE devices on the RBSU/RBSS transmit and receive wire pairs as shown in
Figure 5-8 . This power
arrangement is also known as phantom power.
Each of the four circuits on RBSU/RBSS can be connected to share the R40S using option switches on
the PCBs (see
Table 5-3 ). Before using the R40S as a backup power source, make sure the TE devices
do not require more power than the R40S can supply and the TE is compatible with the ISDN PS-1
power arrangement.
RX
TX
RBSU/RBSS
NT1
RX
TX
PSTN
RX/TX
U T S
BRI
(2-wire)
BRI-TE
(4-wire)
BRI-NT
(4-wire)
3336
S, T, and U are ISDN reference points.
TE = S-type Terminal Equipment
TA = S-type Terminal Adaptor
TE-1
or
TA
1
2
. .
.
TE-1
or
TA