Nortel Networks 553-3001-211 manual 628 of 894 NT8D15 E&M Trunk card

Page 628 of 894 NT8D15 E&M Trunk card

Signaling interface

All signaling messages for the trunk are three bytes long. The messages are transmitted in channel zero of the DS30X in A10 format.

Configuration information for the E & M trunk is downloaded from the CPU at power up and by command from maintenance programs. Seven configuration messages are sent. One message is sent to each unit (4) to configure trunk type, signaling type, balance impedance etc. Three messages are sent per card to configure the make/break ratio, A/µ-Law operation.

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 µ-Law modes.

The signaling and control circuits on the card perform the following functions:

•provide an 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)

553-3001-211 Standard 2.00 September 2004