Toshiba Strata Dk14, Dk40i, Dk424 Installation And Maintenance Manual

							DK424 T1
Applications
Strata DK I&M    5/996-11
DK424 T1
 Applications
Each RDTU T1 PCB requires the following connecting equipment and cables to provide service  
(see the following sections and Figure 6-4).
RDTU to Network
If the RDTU must interface to a public telephone network or common carrier T1 circuit, the 
RDTU must be connected to a CSU. Use the NDTU cable (30 ft. cable supplied with RDTU) to 
connect the RDTU to the CSU. The function of the CSU is to provide the required interface 
between the RDTU PCB and the Public Telephone or Carrier Network. The interface created by 
the CSU normally provides protection and capabilities for loop back testing both the Network 
equipment and the RDTU PCB.
Connecting the CSU to the Network Interface Unit (NIU) is specified by the CSU manufacturer—
see CSU installation documentation. Toshiba does not supply the cables and connectors required 
to connect the CSU to the NIU (see “RDTU Cable Installation”).
RDTU to PBX T1 (Separated More Than 655 ft.)
If the RDTU must interface to a customer’s premises T1 circuit (PBX, key/hybrid, or another 
DK424) to provide Tie line service, the RDTU must be connected to a CSU (with Toshiba NDTU 
cable) if the other customer premise T1 equipment is more than 655 ft. from the RDTU. The T1 
span on the other end must also connect to a CSU.
Figure 6-4 RDTU Connection to Digital Network or OCC
The RDTU equalization switch (SW1) must be set for “SHORT” cable length because RDTU will 
be connected to the CSU with the 30 ft. NDTU cable (see Table 6-2).
Connecting CSU to CSU and CSU to the far-end PBX T1 is specified by the CSU manufacturer—
see the CSU installation documentation. Toshiba does not supply cables or connectors to connect 
CSU to CSU (Cable A) or CSU to the far end PBX (Cable B).
Strata DK
RDTUCSUDS-1 TOSHIBA
NDTU 30 ft CableTelco Digital Network or
Common Carrier 
(AT&T, MCI, etc.)
Network 
Interface 
Unit
1665 
						

							DK424 T1
Applications
6-12Strata DK I&M    5/99
RDTU to PBX T1 (Separated Less Than 655 ft.)
If the RDTU is within 655 ft. of the far-end PBX T1 circuit, a CSU is not required. However, 
connecting a RDTU T1 span to another PBX or Key/Hybrid T1, in a Tie line configuration at a 
distance less than 655 ft. (without a CSU) will require a customer provided special cable. The 
transmit and receive pair of this span cable must be separated by at least five cable pairs and the 
wires must be 24 AWG, twisted pair, otherwise 22 AWG, ABAM type cable must be used.  See 
“RDTU Cable Installation” on Page 6-14.
CSUs are not required if the RDTU is less than 655 ft. from the channel bank (see Figure 6-5).
Two CSUs (customer provided) are required if the RDTU is more than 655 ft. from the customer 
premise channel bank (see Figure 6-6). 
In Figures 6-5 and 6-6, special cable and connectors are customer-provided.
Figure 6-5 Required Cables/Connectors for RDTU Connection at Distances of Less than 655 (200 Meters)
Figure 6-6 RDTU Connection via CSU and Channel Bank
R (1)
T (26)
R1 (2)
T1 (27)(2) Rr
(27) Rt
(1) Tr
(26) Tt
(Maximum 655 ft.) Strata DK424
PBX or other CPE
PBX/Key 
System
or...
Channel
Bank
RDTU Amphenol 
Connector
(Pin No.) RDTU
T1Customer-provided Special 
Cable/Connectors
RDTU
Transmit
RDTU
Receive
PBX Amphenol 
Connector
1667
E&M 
Tie LinesAnalog PBX
or...
Key System
RDTU Strata DK424
More than 655 ft.Channel
Bank CSU CSU TOSHIBA
NDTU Cable
30 ft. max.
 Analog 
Tie Line Cable B
Cable A
1668 
						

							DK424 T1
Hardware and Cabling
Strata DK I&M    5/996-13
DK424 T1
Hardware and Cabling
RDTU Cable Length Switch
The distance between the DK424, RDTU and CSU or RDTU to other Customer Premise 
Equipment (CPE) T1 may vary (0~655 ft.) as shown. (See Figures 6-4, 6-5, and 6-6.) The RDTU 
interface transmitter must be equalized and its impedance must be matched to the cable length 
connecting the RDTU to the CSU or other CPE, T1. 
RDTU transmit equalization/ impedance matching is accomplished by setting RDTU SW1 for the 
proper cable length (see Figure 6-5 for SW1 location and “SW1 Equalizer Switch and Loop Back 
Jumpers (Internal Option)” on Page 6-2 for SW1 setting instruction).
RDTU Loop Back Jumper Plugs
The RDTU PCB provides jumper plugs for loop back testing. Loop back tests are described in   
“Loop Back Testing” on Page 6-16.
RDTU Front Panel Indicators
The RDTU PCB provides seven LED indicators to show the status of RDTU: Busy or Idle 
condition, Alarm status, and Synchronization status. See Table 6-2 for the function of each status 
LED. Figure 6-2 shows the LED locations.Busy LED (BSY)—Turns on when one or more RDTU 
channels (lines) are in use. Also, when the RDTU does not receive the far end 1.544 mbs carrier 
signal, the RDTU will cause the BSY to be on steady.
Alarms are used to indicate potentially serious telephone network problems. Example: when 
monitoring a T1 network, if a Blue or Yellow alarm is indicated, it can be concluded that there is a 
cable fault or some other serious transmission impairment.
©Frame Alarm (FALM)—This LED turns ON steady if the RDTU has not achieved 
synchronization or when the span cable is not connected.
©Multi-Frame Alarm (MFALM)—LEDs turn ON steady if the RDTU receives the 1.554 mbs 
T1 carrier from the far end, but has not achieved Frame synchronization or when the span 
cable is not connected. Also, if the RDTU is set for SF and the far end is sending ESF (or vice 
versa), the MFALM LED will be ON steady.
©Red Alarm (FALM and MFALM)—When FALM and MFALM are both ON steady, a Red 
alarm condition exists. This indicates that the RDTU does not detect a proper carrier signal 
(1.544 mbs T1) on its receive pair and the RDTU is not synchronized. When the Red alarm 
condition exists, the RDTU should turn the BSY LED ON steady and attempt to send a Yellow 
alarm signal (RDTU YALM LED flashes) to the far end T1 circuit.
©Yellow Alarm (YALM)—When the far end network or CPE T1 does not detect the RDTU 
transmitted 1.544 mbs T1 carrier signal on its receive pair the far end T1 sends a Yellow alarm 
signal pattern to the RDTU—the RDTU should turn on the YALM LED (the YALM repeats 
the signal it receives from the far end—flashing or steady). If the RDTU does not receive the 
far end carrier signal, the RDTU sends the Yellow alarm signal to the far end and causes the 
BSY and YALM LEDs to flash.
©Blue Alarm (BALM)—The Blue alarm, also known as the Alarm Indication Signal (AIS), is 
detected by the RDTU. This signal is sent by the Far End Network equipment to RDTU when 
it loses the carrier from a Network T1 circuit (other than RDTU). This signal assures that the 
RDTU maintains synchronization when there is a problem between two Network Nodes. The 
RDTU BALM also lights if the far end sends a Blue alarm signal during loop back. The RDTU 
sends a Blue alarm signal when loop-back test is being performed. 
						

							DK424 T1
Hardware and Cabling
6-14Strata DK I&M    5/99
Synchronization LEDs
©Primary Synchronization (PSYNC) LED (see Figure 6-1 on Page 6-6) – If one RDTU PCB is 
assigned as the Primary Timing T1 PCB in Program *42, the PSYNC LED of this RDTU PCB 
flashes when it is synchronized with the far end T1 span line clock provider. If the Primary 
RDTU is not synchronized with the clock provider, the PSYNC LED will be ON steady. The 
SSYNC LED of the Primary sync RDTU PCB should always be OFF. The Primary sync 
RDTU PCB synchronizes the RTCU (time-switch) to the clock signal it receives from the T1 
span circuit to which it is connected. The RTCU then synchronizes the DK424 PCM talk path 
(time-switch) to the far end PCM talk path.
©Secondary Synchronization (SSYNC) LED – If an RDTU PCB is assigned as the Secondary 
time T1 PCB in Program *42, its SSYNC LED will be ON steady (standby mode) when the 
DK424 is synchronized to the Primary T1 clock provider. In the event of a loss of Primary 
synchronization (when 4 out of 12 consecutive frame timing bits are in error) the DK424 
switches from synchronizing to the Primary RDTU span line clock to the span line clock 
connected RDTU designated as the Secondary Timing Reference. When the DK424 is 
synchronized to the Secondary Reference RDTU, the PSYNC LED on the Primary Reference 
RDTU turns on steady and the SSYNC LED on the Secondary Reference RDTU will flash.
©Run Free (PSYNC/SSYNC) – If the RDTU PCB is the clock provider to the Far-end T1 span 
circuit both the PSYNC and SSYNC LEDs are always OFF.
RDTU Cable Installation
The RDTU PCB is shipped with a Toshiba NDTU cable for connecting the RDTU PCB to a CSU. 
The NDTU is a 30 ft. cable and is specially made to conform with EIA specifications (see Figure 
6-7). 
All other cables required to connect the T1 span line to the RDTU PCB are customer-supplied and 
must conform with EIA specification, see the Notes of Figure 6-7. Almost all CSU manufacturers 
supply cables that comply with T1 span specifications for connecting the CSU to customer 
premise equipment (like DK424, RDTU) to the Network Interface equipment. 
						

							DK424 T1
Hardware and Cabling
Strata DK I&M    5/996-15
DK424 T1
1670
RDTU PCB (26)
(1)
(27)
(2) T
R
T1
R1 Black 
Red
White
Green Customer-supplied Cable (See Notes) RDTU To Customer Premise Equipment (CPE) T1
RDTU Amphenol CPE T1 (PBX 
or Key 
System) or 
Channel Bank
655 Feet MaximumTransmit
Receive (4)  T
(5)  R
(1)  T1
(2)  R1 Network
Interface Unit
USOC-RJ48C
or RJ48X
8-Pin Modular
(RJ45 Type Jack)NDTU DB-15
Connector (Male)
DB-15
Connector (Female) Customer Supplied
Cable (See Notes)RDTU To Network or Long Distance T1 Provider
NDTU
Amphenol
Connector (Male) (1)
(9)
(3)
(11)Customer-
supplied
CSURDTU PCB (26)
(1)
(27)
(2) T
R
T1
R1 Black
Red
White
Green (1)
(9)
(3)
(11)NDTU Cable (30 ft. Maximum)
Transmit
Receive
Figure 6-7 RDTU Cable Connections
Notes
lPins 2 and 4 of the DB-15 connector in most CSUs are frame ground. No connection is 
required.
lNDTU cable is supplied with RDTU PCB (30 ft. maximum).
lSet RDTU SW1 switch for proper loop length per DK14.
lCustomer-supplied span cables must be 22 AWG, ABAM cable or, if using standard 24 AWG 
twisted pair, the transmit pair must be separated from the receive pair by at least 5-cable pairs. 
Most CSU manufacturers supply cables to connect the CSU to the Network Interface Unit or 
other CPE equipment. 
						

							DK424 T1
Loop Back Testing
6-16Strata DK I&M    5/99
Loop Back Testing
The RDTU provides three loop back test configurations. These loop back tests should be 
performed as required in conjunction with CSU loop back tests (see CSU loop back test 
documentation).
RDTU Self Test
This test should be performed upon initial installation of a RDTU PCB. Program the RDTU per 
“System Programming for T1” on Page 6-3; then perform the RDTU loop back test, per the 
instructions in Figure 6-8, before connecting the far end (CSU, Network, or CPE) T1 span line.
Network/CSU T1 Span Test
This test will verify that the far end (CSU, Network, or CPE) T1 equipment and span cabling is 
functioning properly. This test checks all T1 span cabling including the RDTU Amphenol cable 
and connector. Guidelines for this test are provided in Figure 6-9.
RDTU Self Check
MITEL ChipP1Network
Interface
Unit CSU Remove NDTU Cable
P2 MM8976B
Network
1671
Figure 6-8 RDTU Self Test
Notes
lP1 and P2 to ON position (see Figure 6-2).
lRemove NDTU cable from RDTU amphenol connector.
lAfter about 12 seconds, all RDTU LEDs (except PRI/SEC SYNC) turn OFF.
lAppropriate primary or secondary sync. LED flashes if RDTU is Primary or 
Secondary reference.
lIf RDTU is not a primary or secondary reference, then the Primary and Secondary 
sync LEDs should turn OFF. 
						

							DK424 T1
Loop Back Testing
Strata DK I&M    5/996-17
DK424 T1
Network/CSU/RDTU Span Test
This test checks all equipment that is checked with the test in the above paragraph, but this test 
also checks that the RDTU Mitel LSI chip is functioning. Guidelines for this test are described in 
Figures 6-8~6-10.
NoteLoop back tests with CSU and Network equipment can also be performed when 
connecting the RDTU PCB directly to a customer premise (PBX, Key Hybrid, Channel 
bank) T1 circuit.
The RDTU Self Test is an active test of the RDTU circuit.
The Network/CSU Test checks all cables, the Network and CSU equipment (RDTU is not active).
The Remote Loop Back (RLB) Test is an Active test of RDTU (LSI MM8976B), CSU, Network 
equipment and all cables.
Refer to Figure 6-3 and the CSU manufacturer’s Installation and Maintenance manual for 
information on CSU Local/Network Loopback Tests.
Network/CSU Check
Loop
Back
P1Network
Interface
Unit CSU NDTU Cable
P2
On
OnP26, TT
P1, TR
P27, RT
P2, RRNetwork
1672
Figure 6-9 Network/CSU T1 Span Test
Notes
lP1 and P2 to ON position (see Figure 6-2).
lUnplug RDTU from DK424 back plane.
lCSU or Network T1 equipment should receive its own transmitted signal.
lIndications and results depend on CSU and/or Network equipment. 
						

							DK424 T1
Performance Monitoring
6-18Strata DK I&M    5/99
Performance Monitoring
The performance of the RDTU can be monitored using the Data Dump Mode. This requires an 
RSIU, RSIS, PIOU or PIOUS PCB, an ASCII terminal (or PC) and, if monitoring RDTU 
performance from a remote location, an IMDU or RMDS modem or Hayes compatible modem is 
required.
The RDTU monitoring feature provides a printout (or CRT display) of RDTU detected T1 errors 
as shown in Figure 6-10. 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 6-2 on Page 6-21).
RDTU
RDTU TX Open
MITEL Chip
P4
MM8976BP1/P26 Transmit
P2/P27 ReceiveNDTU Cable RDTU Amphenol Pin Nos.
Network CSUNetwork
Interface
Unit (NIU) 
2581
Top LED
Bottom LEDT = About 1/2 SecondContinue to Cycle when 
P4 is in ON Position 0
0
0
0
0ON Steady
ON
OFF
OFF
OFFOFF
ON
OFF
OFFOFF
OFF
ON
OFFOFF
OFF
OFF
ONON
OFF
OFF
OFF Busy
FALM
FMALM
YALM
BALM
T1 T2 T3 T4 T5 
0
0ON or OFF, Steady
ON or OFF, Steady Primary SYNC
Secondary SYNCLEDS ON RDTU PCB
T6
1673 
						

							DK424 T1
Performance Monitoring
Strata DK I&M    5/996-19
DK424 T1
Figure 6-10 RDTU Performance Monitor Printout
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 6.55 x 104 
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.
T1 ERROR DISPLAY
T1ERR
DTU NO = 1
SYNCHRO BIT ERROR = XXXX TIMES (1 TIME = 1024 ERRORS)
BIPOLAR VIOLATION ERROR = XXXX TIMES (1 TIME = 256 X 256 ERRORS)
SLIP ERROR = XXXX TIMES (1 TIME = 256 ERRORS)
CRC ERROR = XXXX TIMES (1 TIME = 256 ERRORS)
DTU NO = 2
SYNCHRO BIT ERROR = XXXX TIMES (XXXX = 0~9999)
BIPOLAR VIOLATION ERROR = XXXX TIMES
SLIP ERROR = XXXX TIMES
CRC ERROR = XXXX TIMES
DTU NO = 3 = XXXX TIMES
SYNCHRO BIT ERROR = XXXX TIMES
BIPOLAR VIOLATION ERROR = XXXX TIMES
SLIP ERROR = XXXX TIMES
CRC ERROR = XXXX TIMES
DTU NO = 4
SYNCHRO BIT ERROR = XXXX TIMES
BIPOLAR VIOLATION ERROR = XXXX TIMES
SLIP ERROR = XXXX TIMES
CRC ERROR = XXXX TIMES
DTU NO = 5
SYNCHRO BIT ERROR = XXXX TIMES
BIPOLAR VIOLATION ERROR = XXXX TIMES
SLIP ERROR = XXXX TIMES
CRC ERROR = XXXX TIMES
DTU NO = 6
SYNCHRO BIT ERROR = XXXX TIMES
BIPOLAR VIOLATION ERROR = XXXX TIMES
SLIP ERROR = XXXX TIMES
CRC ERROR = XXXX TIMES 
						

							DK424 T1
T1 Fault Isolation
6-20Strata DK I&M    5/99
ä
To receive the “T1 ERROR DISPLAY” from a terminal (local or remote)
1. Establish communication with the terminal or PC using a communication software (e.g., 
Procomm®).
2. Enter the security code, and press Enter
 (or Return
).
3. At the >MODE
 prompt, type DUMP
 (must be all caps), press Enter
 (or Return)
. The >D
 
prompt displays on your screen.
4. At the >D
 prompt, type T1ERR
 and press Enter
 (or Return
). The display (see Figure 6-10) 
shows all RDTU PCBs (DTUNO=1~DTUNO=8) even if the associated RDTU (1~8) is not 
installed. The ERROR counter can only be reset by turning the DK424 OFF and ON.
Use Table 6-2 for recording customer’s problems.
ä
To exit the dump mode
äAt the >D prompt, type QUIT, press Enter (or Return); the >MODE prompt displays.
T1 Fault Isolation
T1 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 T1 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 T1 test equipment to help find the 
cause of a failure, or at least determine if system hardware is functioning properly.
The DK424 also provides T1 “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 T1 performance without the expense of test equipment or 
without taking the T1 circuit out of service. The T1 error check is particularly useful for 
monitoring the T1 circuit for intermittent problems that may become more serious as time 
progresses (see “RDTU Performance Monitor Printout” on Page 6-19).
If experiencing problems with an RDTU span circuit, refer to Flowcharts 6-1~6-3 to isolate the 
fault. The flowcharts in this section use the same logic symbols as those used in DK. Document 
error information in Table 6-2, “RDTU T1 Error Record” on Page 6-21.