OpenVox B100E on DAHDI User Manual page 30

 Extended Passive Bus Mode allows connection to 8 terminals at
distances of up to 500 meters from the NT-1.
 Star Bus Mode allows interconnection of up to 8 terminals to a central
NT-1. Each terminal can be up to 1 KM from the NT-1.
 The NT-1 unit has configurable jumpers to apply a 100-ohm
termination to the S-Interface signal pairs. Usually, these jumpers
will be in. Rules of termination is similar to that of the SCSI-bus:
the NT-1 will have 100-ohm terminators applied, and the farthest
TE1/TA device will have 100-ohm terminators.
 Optional power to the NT-1 can be applied from pins 7 and 8 of
the S-Interface RJ-45 jack. This is usually not used.
 Many NT-1 units provide "phantom-power" (sealing current)
between the transmit (4,5) and receive (3,6) leads. In these cases,
the Transmit (4,5) leads will be negative with respect to the
Receive (3,6) leads. This is often selectable in the NT-1.
Whenever possible, it is recommended that this option be disabled.
As a general rule-of-thumb, most PC cards, routers, and other data
communications equipment do not require power from the S/T
interface. ISDN telephones usually require power from the S/T
interface.
 Most NT-1 units will ship with a wall-mount transformer power
supply for the NT-1.
OpenVox Communication Co. LTD.
VoIPon www.voipon.co.uk sales@voipon.co.uk Tel: +44 (0)1245 808195 Fax: +44 (0)1245 808299
B100E on DAHDI User Manual
URL: www.openvox.cn
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