Nortel Networks 553-3001-211 manual Card mix, Address decoding, Port specifications

Page 386 of 894 NT6D80 MSDL card

Card mix

A system that exclusively uses MSDL cards can support up to 16 such cards, providing 64 ports. These ports can be used to run various synchronous and asynchronous operations simultaneously.

The system will also support a mix of interface cards (MSDL, DCHI, and ESDI for example). However, using multiple card types will reduce the number of cards and ports available.

Address decoding

The MSDL card decodes the full address information received from the system. This provides 128 unique addresses. Since MSDL ports communicate with the CPU using a single card address, the system can support 16 MSDL cards providing 64 ports.

The MSDL card addresses are set using decimal switches located on the card. These switches can select 100 unique card addresses from 0 to 99.

An address conflict may occur between the MSDL and other cards because of truncated address decoding by the other cards. For example, if a DCHI port is set to address 5, its companion port will be set to address 4, which means that none of the MSDL cards can have hexadecimal address numbers 05H, 15H, …75H, nor addresses 04H, 14H, …74H. To avoid this conflicts system software limits the MSDL card addresses from 0 to 15.

Port specifications

The MSDL card provides four programmable serial ports configured with software as well as with switches for the following modes of operation:

Transmission mode Configure an MSDL port for synchronous or asynchronous data transmission using LD 17.

Synchronous transmission uses an external clock signal fed into the MSDL.

553-3001-211 Standard 2.00 September 2004