Nortel Networks Circuit Card - Manual (Page 857)

QPC513 Enhanced Serial Data Interface card Page 857 of 906
Circuit Card Description and Installation
Fault detection
Firmware on the ESDI card detects hardware faults on the card and link level
LAPB protocol faults. It reports the faults to the CPU when predetermined
thresholds (downloaded at initialization) have been exceeded.
Fault isolation
The ESDI/Command and Status Link (CSL) maintenance software takes the
ESDI card out of service when the out-of-service thresholds are exceeded for
the following:
• LAPB error conditions (for example, retransmission, Cyclic Redundancy
Check (CRC) errors, overrun/underrun errors)
• Physical or link errors
• Detected hardware errors
Connection characteristics
The two DB-25 connectors on the front panel of the ESDI card provide
connections to each of the two I/O ports. The electrical interface of these
connectors is a modified version of the RS-422-A standard designed to drive
high-speed data over long cable lengths (up to 100 ft). Table 267 shows the
interconnection specifications for these ports.
Table 267
QPC513 interconnection specifications
Distance Interconnection
<15.24 m (<50 ft) Regular 25-conductor cable
>15.24 m and <30.48 m
(>50 ft and <100 ft)
Twisted pair for balanced circuits
>30.48 m (>100 ft) Network interface devices such as stand-alone
modems or DS-1 facilities using
Asynchronous/Synchronous Interface Module
(ASIM) and Data Line card (DLC)