STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
PROPRIETARY AND CONFIDENTIAL
87
Register 005H: Transmit Framing and Bypass Options
Bit
Type
Function
Default
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
PATHCRC
G706ANNBRAI
SIGAEN
OOCMFE0
FDIS
FBITBYP
CRCBYP
FDLBYP
0
0
0
0
0
0
0
0
This register allows software to configure the bypass and framing options of the
transmitter, the use of the Signaling Alignment block, and controls the global
transmit framing disable.
PATHCRC:
This bit only has effect in E1 mode.
When in E1 mode, the PATHCRC bit allows upstream block errors to be
preserved in the transmit CRC bits. If PATHCRC is a logic 1, the CRC-4 bits
are modified to reflect any bit values in BTPCM which have changed prior to
transmission. When PATHCRC is set to logic 0, a new CRC-4 value
overwrites the incoming CRC-4 word. For the PATHCRC bit to be effective,
the FPTYP bit of the Transmit Backplane Frame Pulse Configuration register
must be a logic 1; otherwise, the identification of the incoming CRC-4 bits
would be impossible. The PATHCRC bit only takes effect if the GENCRC bit
of the E1-TRAN Configuration register is a logic 1 and either the INDIS or
FDIS bit in the same register are set to logic 1.
G706ANNBRAI:
When in E1 mode, the G.706 Annex B RAI bit, G706ANNBRAI, selects
between two modes of operation concerning the transmission of RAI when
the COMET is out of CRC-4 multiframe. When G706ANNBRAI is logic 1, the
behaviour of RAI follows Annex B of G.706, i.e., RAI is transmitted only when
out of basic frame, not when CRC-4-to-non-CRC-4 interworking is declared,
nor when the offline framer is out of frame. When G706ANNBRAI is logic 0,
the behaviour of RAI follows ETSI standards, i.e., RAI is transmitted when out