Nortel NT1R20 Description page 183

NT5D33 and NTRB34 Line-side E1 Interface Cards Page 159 of 290
For 75 ohm coaxial installations, E1 signaling for all 30 channels is
transmitted over P2 connector pins 1, 3, 9, and 11 though an adapter and out
two coaxial connectors Tx (transmit) and Rx (receive). Tx is the LEI output,
and Rx is the LEI input from the E1 stream. E1 transmit and receive pairs
must be turned over between the LEI and the CPE equipment that is
hardwired without carrier facilities. If the LEI is connected via E1 carrier
facilities, the transmit and receive pairs must be wired straight through to the
RJ48 at the Telco demarc, the LTU, or other E1 carrier equipment. The E1
CPE equipment at the far end will likewise have Tx and Rx wired straight
from the RJ48 demarc at the far end of the carrier facility.
External Alarm Connections
P3 connector pins 1, 2 and 3 can be plugged into any external alarm-sensing
hardware. Plug the DB9 male connector labeled "P3" into an external alarm.
These connections are optional, and the functionality of the LEI is not
affected if they are not made.
The MMI monitors the E1 link for specified performance criteria and reports
on problems detected. One of the ways it can report information is through
this external alarm connection. If connected, the LEI's microprocessor will
activate the external alarm hardware if it detects certain E1 link problems it
has classified as alarm levels 1 or 2. See "Man-Machine E1 maintenance
interface software" on page 165, for a detailed description of alarm levels and
configuration. If an alarm level 1 or 2 is detected by the MMI, the LEI will
close the contact that is normally open, and will open the contact that is
normally closed. The MMI command "Clear Alarm" will return the alarm
contacts to their normal state.
MMI Connections
P5 connector pins 2, 3, 5, 7 and 9 are used to connect the LEI to the MMI
terminal, connecting LEIs in a daisy chain for access to a shared MMI
terminal. When you log into a LEI, "control 2" is asserted by that card, which
informs all of the other cards not to talk on the bus, but rather to pass the data
straight through. The pins labeled "control 1" are reserved for future use. As
with the external alarm connections, MMI connections are optional. You can
link up to 128 LEIs, located in up to 16 separate IPE shelves, to one MMI
terminal using the daisy chain approach.
Line cards Description