XRT83SL314 datasheet(27/83 Pages) EXAR

27 / 83 page

XRT83SL314

14-CHANNEL T1/E1/J1 SHORT-HAUL LINE INTERFACE UNIT

REV. 1.0.1

2.6.3.4

NLCD (Network Loop Code Detection)

The Network Loop Code Detection can be programmed to detect a Loop-Up, Loop-Down, or Automatic Loop

Code.

If the network loop code detection is programmed for Loop-Up, the NLCD will be set "High" if a

repeating pattern of "00001" occurs for more than 5 seconds.

If the network loop code detection is

programmed for Loop-Down, the NLCD will be set "High" if a repeating pattern of "001" occurs for more than 5

seconds. If the network loop code detection is programmed for automatic loop code, the LIU is configured to

detect a Loop-Up code.

If a Loop-Up code is detected for more than 5 seconds, the XRT83SL314 will

automatically program the channel into a remote loopback mode. The LIU will remain in remote loopback even

if the Loop-Up code disappears. The channel will continue in remote loop back until a Loop-Down code is

detected for more than 5 seconds (or, if the automatic loop code is disabled) and then automatically return to

normal operation with no loop back. The process of the automatic loop code detection is shown in Figure 15.

FIGURE 15. PROCESS BLOCK FOR AUTOMATIC LOOP CODE DETECTION

Automatic Remote

Loopback

Loop-Up

Code for

5 sec?

Yes

Loop-Down

Code for

5 sec?

Yes

Disable Remote

Loopback

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