Patton electronic 1094A user manual Loops and Patterns, Local Loop, with 511/511E

5.3.2 Loops and Patterns

The following section describes the Test Modes used in the Model 1094A. At the bottom of each Test Mode, a figure is included to show the data path.

Local Loop There are two different modes of operation for a

Framer	Pattern	Loop
	Gen/Det	Control
	Processor

Line

Loop Pattern

Control Gen/Det

Processor

Framer

Local Loop depending on the status of the units

at the time that the Local Loop is initiated. If the

Figure 7. Block Diagram Local Loop Mode 1

units are not in linked (NS LED on) and the

Local Loop is initiated, either by the front panel

switch or the DTE interface, the unit will enter

mode 1. If the units are linked, NS LED off, then

the unit will enter a mode 2 Local Loop.

A Mode 1 Local Loop is shown in Figure 7.

When the Local Loop is initiated, either by the

Framer

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

front panel switch or the DTE interface, the loop

will be activated within the local Processor. The

data present at the local DTE interface will be

looped back to the local DTE by the Loop

Control block within the Processor. Any data

present on the line or at the far end DTE inter-

face is invalid. The remote unit will remain in the

StartUP mode, NS LED on, CTS LED yellow,

and CD LED yellow, 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 8.

When the Local Loop is initiated, either by the

front panel switch or the DTE interface, two sep-

arate 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.

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	Figure 8. Block Diagram Local Loop Mode 2
Local Loop	When the unit is placed into a Mode 1. Local
with 511/511E	Loop and the 511/511E pattern generator is acti-
	vated, the local pattern generator begins send-
	ing 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 discon-
	nection (this would cause the units' Restart pro-
	cedure to start). What we have done to allow
	this mode to work is to add time outs for the pat-
	tern generators. When the 511/511E is initiated,
	the line restart procedure is changed to one
	minute. The 511/511E pattern will timeout after
	45 seconds. So if the 511/511E is turned on dur-
	ing a local loop, the restart procedure is set to
	one minute, but the 511/511E pattern will time
	out after 45 seconds, allowing the framer to
	begin seeing framed packets (and not restart
	the box).
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