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Page 302 of 894 NT5D60/80 CLASS Modem card (XCMC)
553-3001-211 Standard 2.00 September 2004
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 4.0 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 4.0
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