XRT86VL32IB datasheet(32/153 Pages) EXAR

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XRT86VL3X

T1/E1/J1 FRAMER/LIU COMBO - ARCHITECTURE DESCRIPTION

REV. 1.2.2

3.6

DS1/E1 Datalink Transmission Using the HDLC Controllers

The transmit framer block can insert data link information to outbound DS1/E1 frames. The data link

information can be inserted from the following sources.

• Transmit Overhead Input Interface (TxOH)

• Transmit HDLC1 Controller

• Transmit Serial Input Interface (TxSER)

NOTE: HDLC1 is the dedicated controller for transmission of LAPD messages through the datalink bits. If the datalink bits

are not used for LAPD messages, then HDLC1 can be used through the D/E time slots as with HDLC2 and HDLC3.

The Transmit Data Link Source Select bits within the Transmit Data Link Select Register (TSDLSR) determine

the source for the data link bits in ESF, SLC®96, or T1DM for DS1 and CRC multi frame for E1. Each Transmit

HDLC Controller contains four major functional modules.

• Bit-Oriented Signaling Processor

• LAPD Controller

• SLC®96 Data Link Controller

• Automatic Performance Report (APR) Generation

3.7

Transmit BOS (Bit Oriented Signaling) Processor

The Transmit BOS Processor handles transmission of BOS messages through the data link channel. The

processor can be set for a specific amount of repetitions a certain BOS message will be transmitted, or it may

be placed in an infinite loop. The processor can also insert a BOS IDLE flag sequence and/or an ABORT

sequence to be transmitted on the data link channel.

3.7.1

Description of BOS

Bit-Oriented Signaling messages are a 16-bit pattern of which a 6-bit message is embedded as shown in the

following table.

Where D5 is the MSB and D0 is the LSB. The rightmost "1" is transmitted first. BOS is classified into the

following two groups.

• Priority Codeword Message

• Command and Response Information

3.7.2

Priority Codeword Message

A Priority Codeword Message is preemptive and has the highest priority among all data link information. A

Priority Codeword indicates a condition that is affecting the quality of service and thus shall be transmitted until

the condition no longer exists. The duration of transmission should not be less than one second. A priority

codeword may be interrupted by software for 100 milliseconds to send maintenance commands with a

minimum interval of one second between interruptions. Yellow alarm (00000000 11111111) is the only priority

message defined in industry standards.

3.7.3

Command and Response Information

Command and Response Information is transmitted to perform various functions. The BOS Processor can

send a command and response by transmitting a minimum of 10 repetitions of the appropriate codeword

pattern. A Command and response data transmission initiates action at the remote end, while the remote end

will respond by sending Bit-Oriented response message to acknowledge the received commands.

The

activation and deactivation of line remote loop-back and local payload loop-back functions are of this type.

BOS MESSAGE FORMAT

XRT86VL32IB Datasheet(PDF) 32 Page - Exar Corporation

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