AT&T 518-600-016 manual Theory of Operation

If you use a 008 module in this slot, you must provide for outside lines using another module.

The 408 module has a port processor to handle real- time intensive tasks such as ATL line protocol and central office rotary outpulsing. The port processor receives instructions from the main processor over the I/O bus. The instructions are stored in the dual port RAM. Buffer circuitry interfaces the I/O bus to the port processor.

The 408 module converts analog signals to digitaI for switching. Analog signals come into the 408 module through the outside lines and are converted to digital levels by coder-decodes (codecs). Voice and data signals going to the station jacks are converted to analog signals by codecs. Interface circuitry couples the analog output to the station jack. The DSE interfaces voice and data with the TDM bus. The main processor (through the 1/0 bus) directs the DSE to place or remove samples from the TDM bus in specific time slots.

●008D Module. The 008D Digital Module provides a digital interface to the system for PCs and other data devices. This module does not require codecs because no analog to digital conversion is required. Data flow through the module is controlled by the port processor, which receives its instructions from the I/O bus. Dual Line Interface (DLI) circuitry assures proper clocking and synchronization during all transfer cycles.

●012 Module. The 012 Module interfaces basic telephones to the MERLIN II system. It provides the -48 VDC tip/ring voltage and monitors the circuit for tip/ring conditions. The 012 module converts analog signals into digital levels for interface to the TDM bus and provides -24 VDC for the Ring relay. When a basic telephone goes off-hook and dials a number, ring control circuitry closes the ring voltage relay. At this point, ring control circuitry outputs signals to the port

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