DS21352 datasheet(47/137 Pages) DALLAS

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DS21352/DS21552

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Table 7-2 ALARM CRITERIA

ALARM

SET CRITERIA

CLEAR CRITERIA

Blue Alarm (AIS) (see note 1

below)

when over a 3 ms window, 5 or

less zeros are received

when over a 3 ms window, 6 or more zeros are

received

Yellow Alarm (RAI)

1. D4 bit 2 mode(RCR2.2=0)

2. D4 12th F–bit mode

(RCR2.2=1; this mode is also

referred to as the “Japanese

Yellow Alarm”)

3. ESF mode

when bit 2 of 256 consecutive

channels is set to zero for at least

254 occurrences

when the 12th framing bit is set

to one for two consecutive

occurrences

when 16 consecutive patterns of

00FF appear in the FDL

when bit 2 of 256 consecutive channels is set to

zero for less than 254 occurrences

when the 12th framing bit is set to zero for two

consecutive occurrences

when 14 or less patterns of 00FF hex out of 16

possible appear in the FDL

Red Alarm (LRCL) (this alarm

is also referred to as Loss Of

Signal)

when 192 consecutive zeros are

received

when 14 or more ones out of 112 possible bit

positions are received starting with the first one

received

NOTES:

1. The definition of Blue Alarm (or Alarm Indication Signal) is an unframed all ones signal. Blue alarm detectors should be

able to operate properly in the presence of a 10E–3 error rate and they should not falsely trigger on a framed all ones signal.

The blue alarm criteria in the DS21352/552 has been set to achieve this performance. It is recommended that the RBL bit be

qualified with the RLOS bit.

2. ANSI specifications use a different nomenclature than the DS21352/552 does; the following terms are equivalent:

RBL = AIS

RCL = LOS

RLOS = LOF

RYEL = RAI

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