Nortel Enterprise 1000 Reference Manual page 108

Page 108 of 236
553-3023-211 Standard 1.00 June 2001
NT8D15 E&M Trunk Card
Signaling and control
The signaling and control portion of the E&M trunk card works with the
system CPU to operate the card hardware. The card receives messages from
the CPU over a signaling channel in the DS-30X loop and returns status
information to the CPU over the same channel. The signaling and control
portion of the card provides analog loop terminations that establish,
supervise, and take down call connections.
Configuration information for the E&M trunk card is downloaded from the
CPU at power-up and by command from maintenance programs.
Configuration messages are sent. One message is sent to configure trunk and
signaling type. The other messages are sent to each card to select the make/
break ratio and the A-Law and Mu-Law modes.
The signaling and control circuits on the card perform the following
functions:
• provide interface between the card and the system CPU
— transmit PCM signals from each of the four units to one DS-30X
timeslot in A10 format (ready to send/clear to send—flow control,
handshake format)
— transmit and receive signaling messages over a DS-30X signaling
channel in A10 format
• decode received messages to set configuration and activate/deactivate
interface relays for PCM loopback diagnostic purposes
• decode outpulsing messages (one per digit) from the CPU to drive
outpulsing relays at 20 pps, 10 pps1 (primary), or 10 pps2 (secondary)
• monitor signals from the trunk interface and generate a message when
required for each state change
• control disabling and enabling of unit or card
• control of A-Law and Mu-Law operation modes
• control of transmission pad settings