General; B. Description Of Circuit Cards; Memory Module; Trunk Module - Mitel SX-5 Manual

SECTION MITL9103-098-180-NA
when reading the descriptive material. The
ab-
breviations used in the description are detailed as
follows
PROM
-
Programmable Read Only Memory
RAM
-
Random Access Memory
C O
-
Central Office
-*
a
DP
-
Dial Pulse Signalling
DTMF
-
Dual Tone Multi-Frequency signal-
ling
GSILS
-
Refers to trunk circuits having
"Ground Start" (GS) or "Loop S W (LS)
facility.
OP-AMP
-
Operational Amplifier
LED
-
Light Emitting Diode
IC
-
Integrated Circuit
RMDP
-
Remote Display Power
General
9.02 The SX-5 is a processor-controlled com-
munications system which employs solid-
state space division switching techniques The
processor, which has overall control of the
system, is a MC6809.
9.03 System control programs are held PROM
and non-volatile (i.e. battery protected)
RAM The working data of the system
(ii
data
which reflects the cwrencstate of the system) is
held in volatile RAM. The processor constantly
receives information over the data lines indicating
the state of all call-processing cwwitry,
ag
line
cwcuits, trunks, receivers, etc Any change in
state causes decisions to be made, and instruc-
tions to be issued by the processor based on
programmed
d a t a
Instructions are implemented
by transferring information along the Address
and Data lines to modify logic states in the
system and the contents of various registers
B. Description of Circuit Cards
Memory Module (Fig. 9-2)
9.05 The Memory Module contains the following
circuit divisions
40 k bytes of PROM, used to store the
system control programs These programs
are loaded at the factory and cannot be
altered by site programming
2 k byte of RAM (volatile) used by the
processor as a fast readlwrite store. At
any given instant it contains information
representing the busy/free states of the
system components
1 k byte of RAM (non-volatile). The content
of this memory is programmed on-site
with data such as system options, class of
service, etc In the event of power failure
the data is maintained for up to 600 hours
A Write Enable Circuit This cirucit inhibits
the writing of data into the non-volatile
RAM when the +5 V supply drops below a
threshoid value
Trunk Module (Fig, 9-3)
9.06 The Trunk Module provides two C O trunk
circuits, an example of which is shown in
Fig
9-3.
Trunks may be set for "loop stad or
"ground start" working by means of a switch
mounted on the trunk module (preset at the fac-
tory to "loop s w 1 .
9.07 Each trunk circuit contains the following
circuit divisions
Swge protection
-
used to protect the
trunk circuit from line transients
Polarity guard
-
used to ensure the correct
direction of current flow through the ac-
tive network of the trunk circuit even if Tip
and Ring are reversed
Current controller
-
limits the swing of
Tip/Ring current within the active ne&ork
of the trunk circuit
9.04 The system logic contains a continuously Incoming/Outgoing differential amplifiers
-
running diagnostic program This program used to couple incoming and outgoing
detects errors in the system memories and audio in order to mute echo paths
causes the ALARM
LED
on the Main Card to flash Outgoing audio pansformer
-
transfers
when such an error is found
outgoing audio to TipIRing current
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