ADTRAN NT1 T400 - Manual (Page 20)

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61212016L1-1 NT1 T400 User Manual 11
APPENDIX B
S/T BUS CONFIGURATIONS
SHORT PASSIVE BUS
The short passive bus configuration allows the connection of up to eight TEs at any
point on the bus. The bus length is limited to 600 feet, as illustrated in Figure B-1.
To select this bus configuration, set switch 1-2 to the Short position. The bus ter-
mination resistors (TRs) can be placed at any point along the bus. If the TEs have
internal TRs that can be optioned, only one TE's TRs should be enabled. The TRs
in the NT1 Type 400 are enabled by setting switches 1-3 and 1-4 to the ON posi-
tion, and switches 1-5 and 1-6 to the OFF position. If the unterminated TEs are
placed within 20 feet of the NT1, set switches 1-3 and 1-4 to the OFF position, and
switches 1-5 and 1-6 to the ON position. The switch settings should always be
maintained, unless an external 100 ¾ resistor is being used. If an external TR is
used, set switches 1-3 through 1-6 to the OFF position.
Figure B-1: Short Passive Bus Configuration
EXTENDED PASSIVE BUS
This bus configuration allows the connection of up to eight TEs at ranges up to
3000 feet from the NT1 Type 400, as illustrated in Figure B-2.
To select this mode, set switch 1-2 to the Long position. A TR must be centrally
located to the TEs. The TRs in the NT1 Type 400 are enabled by setting switches
1-3 and 1-4 to the ON position, and switches 1-5 and 1-6 to the OFF position.
These switch settings should always be maintained, unless an external 100 ¾ re-
sistor is being used. If an external TR is used, set switches 1-3 through 1-6 to the
OFF position.
Figure B-2: Extended Passive Bus Configuration
TR TR* NT1
TE TE TE
* Is not needed if NT1Õs
TR
is used
600
FEET
TR TR* NT1
TE TE
* Is not needed if NT1Õs
TR
is used
3000
FEET
160
FEET