Texas Instruments 990 User Manual page 23

Introduction
USER TASKIUTILITY LEVEL
DATA
MESSAGE
END-TO-END CONTROL LEVEL
I
OVERHEAD
I
PACKET LEVE L
PACKET
HEADER
LINE CONTROL LEVEL
FLAG
ADDRESS
COMMAND,
CRC
FLAG
RESPONSE
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!
.,
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"
! !
FLAG ADDRESS
COMMAND PACKET
OVER- DATA CRC
FLAG
RESPONSE'
HEADER HEADER
MESSAGE
TRANSMISSION FRAME (LINE LEVEL)
2280118
Figure 1-4
Informati on Format under the HDLC Canmunications Pac kage
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