Nortel Networks 553-3001-211 manual Dchi special applications connection

NTAK79 2.0 Mb PRI card Page 745 of 894

•receive clock output

•transmit clock output

The receive and transmit clocks have slightly different bit rates from each other, as determined by the transmit and receive carrier clocks.

The NTAK79 has an onboard D-Channel Handler Interface (DCHI). It is the equivalent to a single port of an NTAK02 SDI/DCH pack. This enables for a completely operational ISDN PRA link with clock synchronization and D-channel on a single circuit card.

The onboard D-channel has one status LED on the NTAK79 faceplate to indicate enabled/disabled states. See Table 234 on page 734.

The on-board DCHI can be operated in two separate modes as defined by an on-board dip switch. It can operate in a standard DCHI mode common to most ISDN standard countries. The U.K. specific mode that uses the DPNSS format is not supported at this time.

Table 242

Settings for the DCHI dip switch (SW1)

Switch	Function	On	Off
S1-1	En/Dis	Enabled	Disabled
S1-2	F/W Mode	DPNSS (not	DCHI
		supported at
		this time)

DCHI special applications connection

The connection between the PRI2 and the on-board D-channel Handler Interface card is also available at the MDF connector. Connections are made to these pins for normal on-board DCHI operation. They can also be used for future or special applications.

The signals conform to the EIA RS-422 standard.

Circuit Card Description and Installation