Patton electronic 1088/K Local Loop with 511/511E, Block Diagram Local Loop Mode 1 with 511/511E

the line or at the far end DTE interface is invalid. The remote unit will remain in the StartUP mode, NS LED on, DSL Link LED stays off, until the local unit is taken out of the Local Loop mode. After the Local Loop is deselected, the units will both be in StartUP mode and the link will be established.

A mode 2 Local Loop is shown in Figure 13. When the Local Loop is initiated, either by the front panel switch or the DTE interface, two separate loop paths will be started. In the first path, data presented to the local DTE interface will be looped back to the local DTE within the framer. In the second path, data presented at the far end DTE will be transmitted to the local DTE and then looped back within the local DTE Loop Control block with the Processor. After the Local Loop is deselected, the units will be placed back into DataMode and the normal data paths will be re-established.

Framer	Pattern	Loop
	Gen/Det	Control
	Processor

Line

Loop Pattern

Control Gen/Det

Processor

Framer

Figure 14. Block Diagram Local Loop Mode 1 with 511/511E

Framer

Pattern	Loop Control	Line	Loop Control	Pattern	Framer
Gen/Det				Gen/Det
	Processor		Processor

Figure 15. Block Diagram Local Loop Mode 2 with 511/511E

Local Loop with 511/511E

When the unit is placed into a Mode 1. Local Loop and the 511/ 511E pattern generator is activated, the local pattern generator begins sending out a 511/511E pattern to the Loop Control block. The Loop Control block will loop this data back to the 511/511E pattern detector block, which will evaluate the data for errors. Because the 511/511E pattern generator is contained within the Processor the data is unframed so the framer will begin seeing unframed packets. The framer receives this unframed data and can not distinguish this information from a line disconnection (this would cause the units' Restart procedure to start). What we have done to allow this mode to work is to add time outs for the pattern generators. When the 511/511E is initiated, the line restart proce-

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