DS26401 datasheet(53/309 Pages) DALLAS

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DS26401 Octal T1/E1/J1 Framer

Table 8-1. T1 Alarm Criteria

ALARM

SET CRITERIA

CLEAR CRITERIA

AIS

(Blue Alarm) (Note 1)

When over a 3ms window, 5 or fewer

zeros are received

When over a 3ms window, 6 or more

zeros are received

RAI

(Yellow Alarm)

1) D4 Bit 2 Mode

(RCR2.0 = 0)

When bit 2 of 256 consecutive

channels is set to zero for at least

254 occurrences

When bit 2 of 256 consecutive channels

is set to zero for less than 254

occurrences

2) D4 12th F-Bit Mode

(RCR2.0 = 1; also referred to

as the Japanese Yellow

Alarm)

When the 12th framing bit is set to

one for two consecutive occurrences

When the 12th framing bit is set to zero

for two consecutive occurrences

3) ESF Mode

When 16 consecutive patterns of

00FF appear in the FDL

When 14 or less patterns of 00FF hex

out of 16 possible appear in the FDL

LOS

(also referred to as

Receive Carrier Loss (RCL))

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

Note 1: The definition of the Alarm Indication Signal (Blue Alarm) is an unframed all-ones signal. AIS 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 AIS alarm criteria in the

DS26401 has been set to achieve this performance. It is recommended that the RAIS bit be qualified with the RLOF bit.

Note 2: The following terms are equivalent:

RAIS = Blue Alarm

RLOS = RCL

RLOF = Loss of Frame

RRAI = Yellow Alarm

RRTS1

Receive Real-Time Status Register 1

0B0h + (200h x n) : where n = 0 to 7, for Ports 1 to 8

Bit #

Name

—

RRAI

RAIS

RLOS

RLOF

Default

All bits in this register are real-time (not latched).

Bit 0 / Receive Loss-of-Frame Condition (RLOF).

Set when the DS26401 is not synchronized to the received

data stream.

Bit 1 / Receive Loss-of-Signal Condition (RLOS).

Set when 192 consecutive zeros have been detected at RPOS

and RNEG.

Bit 2 / Receive Alarm Indication Signal Condition (RAIS).

Set when an unframed all-ones code is received at

RPOS and RNEG.

Bit 3 / Receive Remote Alarm Indication Condition (RRAI).

Set when a remote alarm is received at RPOS and

RNEG.

Bits 4 to 7 / Unused

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