Toshiba Strata DK 280 Installation Manual page 637

11.7 DK280 RDTU (Tl) Performance
Monitoring
The performance of the RDTU can be monitored using
the Data Dump Mode (see Chapter 13-Remote
Maintenance). This requires a PIOU or PIOUS PCB,
an ASCII terminal (or PC) and, if monitoring RDTU
performance from a remote location, an IMDU modem
or Hayes compatible modem is required.
The RDTU monitoring feature provides a printout (or
CRT display) of RDTU detected Tl errors as shown in
Figure 1 l-1 1. There are no time parameters given with
this error report so the time between error count
increments must be monitored manually. Basically the
error count of any error category should not increase
within 24 hour periods (see Table 1 l-5).
The error categories are as follows:
Synchro Bit Error-This counter increments each
time the RDTU detects 1024 synchronization bit
errors.
Bipolar Violation Error-This counter increments
each time the RDTU detects 655x104 bipolar
violations.
Slip error: This counter increments each time the
RDTU detect 256 slips.
CRC Errors: Cyclical Redundancy Check counter
increments each time the RDTU detects 256
CRC-6 errors. This is only available when the
RDTU is in the Extended Super Frame mode.
To receive the '71 ERROR DISPLAY" from a terminal
(local or remote), place the DK280 in the Data Dump
Mode of Chapter 13 and enter "Ti ERR" and press the
RETURN or ENTER key. The display shows all RDTU
PCBs (DTUNO=l
- DTUNO=6) even if the associated
RDTU (l-6) is not installed. The ERROR counter can
only be reset by turning the DK280 OFF and ON.
11.8 Tl Fault Isolation
Tl fault troubleshooting can be complex and may
require expensive test equipment to perform the
necessary fault isolation. Because of the high cost,
many dealers have not purchased Tl test equipment.
As a result, on a cutover when an RDTU does not
synchronize or CO lines simply do not function, the
site technician can only check wiring and cabling.
Without proper test equipment, there is very little that
can be tested. This section provides some procedures
that can be done without Tl test equipment to help
find the cause of a failure, or at least determine if
system hardware is functioning properly.
The DK280 also provides Tl "in-service" monitoring
which allows maintenance personnel to detect line
errors without introducing any disturbances on the
line. This method of testing permits maintenance
personnel to monitor Tl performance without the
expense of test equipment or without taking the Tl
circuit out of service. The Tl error check is particularly
useful for monitoring the Tl circuit for intermittent
problems that may become more serious as time
progresses (see Section 11.7 for more information
regarding Tl performance monitoring).
If experiencing problems with an RDTU span circuit,
start with Flowchart 1 l-l to isolate the fault. The
flowcharts in this section use the same logic symbols
as those used in the Chapter 12.
DK280 RDTU
csu NIU
TRANSMIT
L RECEIVE
r
r
TRANSMIT
LOCAL LOOP BACK NETWORK LOOP BACK
DK0519
General Notes:
l
Notify T7 provider before performing CSU loop back tests.
l
Local loop back and network loop back test cannot be peformed simultaneously.
l
CSU Local/Network Loop back is a function of the CSU, not all CSUs provide this function 7 see CSU /&M
documentation for CSU loop back test procedures.
Figure 11-l 0
CSU local and Network Loop Back Tests
January
1996 11-13