Common Systems Connection Standards AT&T Services, Inc
Date: August 31, 2007 ATT-TP-76450, Issue 9
Copyright ©2004 – 2006, AT&T Knowledge Ventures
All rights reserved
Page 15
(TBOS/TABS)
E2A Discrete Least Preferred
Footnote: A discrete telemetry interface may be provided, on an optional basis, in addition to
higher level interfaces, to provide a summary of alarm and status information for remote
surveillance.
4.6 Alarm Interconnection:
Each NE in a bay shall produce its own unique set of alarm outputs. Pre-designed “busing” of
alarms or alarm leads within a bay is at the discretion of AT&T and shall not be mandated by
the equipment design.
• The interface for TL1 interconnection may be Ethernet RJ45, DB25 or RS422/449 (37 Pin).
• The interface for E2A Serial or Discrete interconnections may be wire-wrap pins or other
non-proprietary connector.
Discrete Alarm Conditions:
4.7 Discrete Alarm Rating
Minimum current carrying capacity - steady state: 0.9 amps at 60 volts for -48 volt applications.
Minimum current (20 msec. duration) during initial contact closure: 0.9 amps at 60 volts for -48
volt applications.
4.8 Open discrete alarm outputs
All discrete alarm outputs shall be designed to provide both
normally open (closed when
corresponding
failures are declared by the system) and
normally closed (opened when corresponding failures
are declared by the system) alarm outputs. The use of Form-C relays may be used to provide
this capability.
4.9 Discrete alarm paired leads
All discrete alarm outputs shall be paired leads (tip and ring) with no common or shared return
leads.
4.10 Discrete alarm dry contacts
All discrete alarm outputs shall be electro-mechanical (non-solid state) dry relay contacts
without any type of constant voltage source or current flow present in a normal or failed state.
