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PRACTICE 553-2201-193
1.05 Meridian SL-i Data Block. Each digital telephone and each
associated data terminal is assigned a separate Terminal Number (TN) in
the Meridian SL-1 data base.
Functions
Page l-2
1.06 Physical. ISDLC circuitry is contained on a 320 mm (12.5 in) by
254 mm
(10
in) printed circuit board. The faceplate of the pack is
equipped with a red LED which lights if the pack is disabled. The rear
of the pack is equipped with an IO-pin connector which provides access
to:
l digital telephones (and associated ASCII terminals or PCs if
equipped)
l
Peripheral Bus
l
power supply
1.07 Configuration. Up to six ISDLC circuit packs can be mounted in
one PE shelf if the remaining slots are used: up to eight ISDLC circuit
packs can be equipped if the remaining slots
are-
left unused. In
addition, up to 18 ISDLC packs can be supported by a single
QPC82
Power Converter. This assumes that no other packs exist that require
power from that converter. If ISDLC circuit packs co-exist with other
peripheral packs associated with the same power converter, the
total..
number of ISDLC circuit packs is calculated as follows:
D
=
3/4
(24
-
Xl
where
D, an integer, is the maximum number of ISDLC packs allowed
X is the number of other circuit packs (e.g., QPC451) associated with
the same power converter.
--
Note: When ISDLC circuit packs serve M3000 Touchphones, this
restriction does not appiy because Touchphones are locally
powered.
1.06 Power
SUDDIV
to Digital Telephones. The ISDLC provides
+30
VDC over each
loop
at
amaximum’current
of 60
mA.
The iine feed
interface can supply power to loops of up to 1067 m (3500
ftl
length
using 22 or 24 AWG gauge wire. 26 AWG guage vire is limited to 745
m (2450 ft). Typical cabling and cross-connections are shown in Fig.
l-l.
1.09 The ISDLC handles messages sent to and from Meridian SL-1 and
digital telephones. Because the message formats and clocking used by
Meridian SL-1 and the digital telephones are different, the ISDLC must
be able to correctly format and synchronize all messages going to and
from these devices. The ISDLC performs the following major tasks:
(a)
Provides 8 bidirectional BPRZ-AM1 coded TCM lines at 512 kbps
to interface up to 8 digital telephones and their associated Data
Options.
._
. . .
9.:;.
.‘.l$
(bl
Multiplexes and demultiplexes 8 integrated voice and data lines and
a 2.56 Mbps DS3OX data stream (used internally by ISDLC)