Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
2.2.9.2 DS0 GROOMING
The configuration for DS0 grooming is contained in the active map. There are eight maps, one for no
network path failure, and seven alternate maps. The transmitted DS0 data is mapped to the received
DS0 data. Each transmitted DS0 has a coded index in the map referred to as the DS0 time slot. The
content of the DS0 time slot is the address of the received DS0 data. Figure 2-9 shows a typical DACS
module routing and its active map. This map is described in detail in paragraph 2.2.9.5.
2.2.9.3 ERROR DETECTION AND SWITCHING
The DACS module constantly monitors its network paths for the following errors: bit error rate
exceeded, all ones signal, loss of data and loss of frame and fast loss of frame. Any one of these errors
can cause an alarm condition, but only if the enable for each has been selected via programming. In
addition, any combination of the four paths can go unused. If unused, a failure in a path will not cause
an alarm or a change in operation. Before switching, the DACS module will wait a selected time delay.
If the error is removed during this period, the DACS module will not switch.
The bit error rate is determined by periodically sampling the CRC failures and comparing them against
a programmed value. The other error conditions are read directly from the internal circuitry of the
Dallas transceiver chip. The loss of frame error is either the severely erred framing event (SEFE) or the
loss of sync (RLOS) signal. The loss of data signal is receive carrier loss (RCL). The all ones signal is
the blue alarm (RBL). The fast loss of frame error is the loss of the fast reframe pattern.
2.2.9.4 ERROR RECOVERY
Although a DACS module has switched, it will still transmit DSOs along the failed network path as
directed by the new map. Any transceiver affected by an error will undergo recovery, even if it has not
caused a switch.
Since a transceiver can only monitor receive errors, it insures that its fellow transceiver gets an error
by sending an all ones signal for 10 ms. After this, the transceiver waits until all errors are cleared. It
allows an extra 50 ms period after errors are cleared to allow the fellow transceiver to fully reframe.
Then it waits an extra recovery time before going fully on line.
M-DACS-T1 RFL Electronics Inc.
October 16, 2012 2-11 (973) 334-3100
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