ADTRAN TRDDS-R Latching Loopback Sequences, Number of, Function, Byte Code, Received Bytes

Table 5. Latching Loopback Sequences

		Number of
Function	Byte Code	Received
		Bytes
Clear existing	Transition in	Minimum of
loopbacks	progress (TIP)	35 TIP bytes
	*0111010
Identify device	Loopback select	Minimum of
to be looped	code (LSC)	35 LSC bytes
	*1010101 - OCU
	*0110001 - CSU
	*1000001 - NIE
Prepare to loop;	Loopback enabled	Minimum of
send MAP code	(LBE)	100 LBE
after 30 bytes	*1010110	bytes
Activate	Far-End voice	Minimum of
loopback	(FEV)	32 FEV
	*1011010	bytes

Minimum of 35 TIP bytes required to disable established latching loopback.

*Don't Care bit

Initiating OCU Latching Loopback to Loop the TRDDS-R (US West Only)

¥SW1-6 on the TRDDS-DP must be ON to enable latching loopback response.

¥From a test system or set, send an OCU latching loopback sequence.

¥Send a selected test pattern and test for error-free operation.

¥Upon completion of this test, advance to Terminating OCU, CSU or NIE Latching Loopback for latching loopback termination.

Initiating CSU Latching Loopback to Loop a DSU/CSU (US West Only)

¥SW1-6 on the TRDDS-DP must be ON to enable latching loopback response.

¥From a test system or set, send a CSU latching loopback sequence. This instructs the TRDDS- DP to notify the TRDDS-R of a CSU loopback request. The TRDDS-R will reverse sealing current to the DSU/CSU. The DSU/CSU should loop when reversed sealing current is detected.

¥Send a selected test pattern and test for error-free operation.

¥Upon completion of this test, advance to Terminating OCU, CSU or NIE Latching Loopback for latching loopback termination.

Table 6. Alternating Loopback Sequences

Function	Received Bytes
Active loopback	Four consecutive bytes of
	specified loopback code
	*0101010	- OCU
	*0101000	- CSU
	*0101100	- DSU
Maintain loopback and	Data byte alternating with
test for bit errors	loopback code
	example:
	*DDDDDD1/*0101010
Clear loopback	Four consecutive data
	bytes without a specified
	loopback code
*Don't care bit

Network Interface Equipment Latching Loopback

The NIE latching loopback method can be used to loop the TRDDS-R at all rates. This loopback test may require programming of the loopback select code or the complete sequence into the test system.

Terminating OCU, CSU or NIE Latching Loopback

¥From a test system or set, send a Latching Loopback Disable command (35 TIP bytes).

Total Reach Dataport Bidirectional Loopback Support

The Total Reach dataport will execute a bidirectional loopback when performing a loopback at the dataport. The Total Reach dataport responds to either the OCU or DS0 loopback command, whichever loopback is applicable to the dataport version. Refer to Table 7 for Total Reach dataport loopback support.

61291021L5-5A Section 61291021L5-5A, Issue 1 Page 5