Nortel DMS-500 - OAS Version 1; Data Loop System

6-14 OAS alarm and Control Circuits
297–1001–122 Standard 06.01 August 1999
OAS Version 1
In the Version 1 OAS, line 1 connects through the DF and the alarm
crosspoint field to a transformer in the office alarm circuit #3 (NT2X43)
card of the OAU. This transformer divides the line into a transmit and a
receive path. From the transformer, the line connects back to the alarm
crosspoint field. At the alarm crosspoint field, the line is multipled to all
odd aisles in the office. At each odd aisle, line 1 is multipled, from frame to
frame, to the A and B talk line jacks. These jacks are on every FSP. A
telephone headset plugged into the talk line jacks of any FSP completes the
speech path.
Line 2 is multipled to all FSP in the even aisles, in the same way. One
difference is that the transformer for line 2 is in the office alarm circuit #3
(NT2X43) card in the standby MTM or ISM. This location ensures that one
talk line is available if a failure occurs in the standby MTM or the OAU.
OAS Version 2
The local talk line circuit is also available in the Version 2 OAS if OAU
dead system cards with unique audibles (NT2X82AA AC, AE, AF, AH or
AK) are in the OAU and standby MTM or ISM. These cards contain the
transformers and related circuits for the local talk lines. The Version 2 talk
line circuit provides the functions described in the previous section.
Data loop system
The office data loop system provides a 4-wire facility for the transmission of
data between the DMS switch and terminal devices. An example of a
terminal device is a mobile switch maintenance VDU. These devices are the
terminal devices on an equipment aisle in the office or at the DF. The
system also provides a facility for point-to-point data transmission between
test equipment at different locations in the office.
The data loop system contains the following hardware:
• three data loop control switches on the ACD
• data link control cards (NT0X89) in the alarm crosspoint field shelf (See
the section on alarm crosspoint field shelf [version 1 OAS] or AXU
[Version 2 OAS]
• a maximum of two data communication ports that originate at terminal
controller cards in the input/output controller (IOC)
• data loop transmit and receive jacks on each FSP or MSP in the office
• data loop jacks mounted on the DF