Nortel Networks Circuit Card User Manual

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 NT5D60/80 CLASS Modem card (XCMC)
The CLASS modem card circuitry is mounted on a 31.75 cm by 25.40 cm 
(12.5 in. by 10 in.) double-sided printed circuit board. The card connects to 
the backplane through a 160-pin edge connector. 
The faceplate of the CLASS modem card is equipped with a red LED that 
lights when the card is disabled. When the card is installed, the LED remains 
lit for two to five seconds as a self-test runs. If the self-test completes 
successfully, the LED flashes three times and remains lit until the card is 
configured and enabled in software, then the LED goes out. If the LED 
continually flashes or remains weakly lit, replace the card.
Functional description
The CLASS Modem card is designed to plug into any one of the peripheral 
card slots of the IPE module. The CLASS modem card supports up to 32 
transmit-only modem resources, using a DS30X interface. Up to 255 modems 
can be configured per system.
The CND transmission process begins with the CS 1000 Release 4.5 software 
sending an initiating message to the CLASS Modem card indicating the 
length of the CND information and the type of the CND information flow to 
be transmitted. In response, the CLASS Modem card assigns a message 
buffer to capture the CND information from the CS 1000 Release 4.5 
software.
System software then sends the CND information to the CLASS Modem 
card, one byte at a time, where it is stored in the message buffer. If the CLASS 
Modem card receives more bytes than were specified in the initiating 
message, then the additional bytes will be discarded and will not be included 
in the CND memory buffer.
Once all of the CND information has been stored in the memory buffer, the 
CLASS Modem card begins transmission when requested by the system 
software. Data is sent one ASCII character at a time. The CLASS Modem 
card inserts a start and stop bit to each ASCII character sent. 
The transmission of the calling party name/number to the terminating 
telephone is accomplished through asynchronous FSK simplex-mode 
transmission at 1200 bits/second over a 2-wire loop, in accordance with the