STANDARD PRODUCT
PM4328 TECT3
DATASHEET
PMC-2011596
ISSUE 1
HIGH DENSITY T1/E1 FRAMER
AND M13 MULTIPLEXER
therefore the TNEG/TMFP signal is suppressed during loopback so that transmit
MFP indications will not be seen nor accumulated as input LCVs. If the UNI bit is
clear, then the interface is configured for bipolar signals RPOS and RNEG,
therefore the TNEG is fed directly to the RNEG input. This diagnostic loopback
can be used when configured as a multiplexer or as a framer only. The DS3
loopback mode is shown diagrammatically in Figure 38.
Figure 38: DS3 Diagnostic Loopback Diagram
F
MX12 #7
MX12 #6
RCLK
R
M
RPOS/
RDAT
RNEG/
RLCV
DS3
F
FRMR
R
F
MX12 #5
R
M
R
R
F
MX12 #4
M
R
R
MX12 #3
MX23
F
M
R
R
F
MX12 #2
MX12 #1
UNI
M
R
TCLK
TPOS/
TDAT
TNEG/
TMFP
F
R
M
DS3
R
R
TRAN
M
R
Optional
AIS
Insertion
DS3 Line Loopback
DS3 Line Loopbacks allow the received DS3 streams to be looped back into the
transmit DS3 paths, overriding the DS3 streams created internally by the
multiplexing of the lower speed tributaries. The transmit signals on TPOS/TDAT
and TNEG/TMFP are substituted with the receive signals on RPOS/RDAT and
RNEG/RLCV. The TCLK signal is also substituted with the receive DS3 clock,
RCLK. While this mode is active, AIS may be substituted for the DS3 payload
being transmitted on the TPOS/TDAT and TNEG/TMFP outputs. Note that the
transmit interface must be configured to be the same as the DS3 FRMR receive
interface for this mode to work properly. The DS3 line loopback mode is shown
diagrammatically in Figure 39. There is a second form of line loopback which
only loops back the DS3 payload. In this mode the DS3 framing overhead is
regenerated for the received DS3 stream and then retransmitted. Line loopback
is selected with the LLOOP bit in the DS3 Master Data source register and
payload loopback is selected by the PLOOP bit in the same register.
PROPRIETARY AND CONFIDENTIAL
155
PMC [ PMC-SIERRA, INC ]
