Rainbow Electronics DS26519 - Manual (Page 68)

DS26519 16-Port T1/E1/J1 Transceiver
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9.9.4.4 Receive SLC-96 Operation (T1 Mode Only)
In an SLC-96-based transmission scheme, the standard Fs-bit pattern is robbed to make room for a set of
message fields. The SLC-96 multiframe is made up of six D4 superframes, hence it is 72 frames long. In the 72-
frame SLC-96 multiframe, 36 of the framing bits are the normal Ft pattern and the other 36-bits are divided into
alarm, maintenance, spoiler, and concentrator bits as well as 12-bits of the normal Fs pattern. Additional SLC-96
information can be found in BellCore document TR-TSY-000008.
To enable the DS26519 to synchronize onto a SLC-96 pattern, the following configuration should be used:
•
RCR1 .5 (RFM) = 1 Set to D4 framing mode.
•
RCR1 .3 (SYNCC) = 1 Set to cross-couple Ft and Fs bits.
•
T1RCR2 .4 (RSLC96) = 1 Enable SLC-96 synchronizer.
•
RCR1 .7 (SYNCT) = 0 Set to minimum sync time.
The SLC-96 message bits can be extracted via the T1RSLC1 –3 registers. The status bit RSLC96 located at
RLS7 .3 is useful for retrieving SLC-96 message data. The RSLC96 bit will indicate when the framer has updated
the data link registers T1RSLC1 –3 with the latest message data from the incoming data stream. Once the RSLC96
bit is set, the user will have 9ms (or until the next RSLC96 interrupt) to retrieve the most recent message data from
the
T1RSLC1 –3 registers. Note that RSLC96 will not set if the DS26519 is unable to detect the 12-bit SLC-96
alignment pattern.