Specifications

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CHAPTER 12: Testing and Troubleshooting
remote unit is error free. Run the test using all available test patterns.
NOTE
If an external BERT tester is available, these additional tests may be
performed:
• DTE & Loop Test
• DTE Only Test
• Loop Only Test
If the unit fails any of these tests or the problem has not been determined, contact
Black Box.
12.3 Local Unit Diagnostics
The local CSU/DSU MS DBU can perform six different tests; see Table 12-3.
Table 12-3. Test AT Commands
Front-Panel Display AT Command Description
DTE & Loop (LL) &T10 TD/RD and RX/TX Loopbacks
Loop Only (RT) &T11 RX/TX Loopback at Network Interface
DTE Only &T1 TX/RX Loopback at DTE Interface
DTE with TP &T8 TX/RX Loopback with Test Pattern
Test Pattern &T9 Transmit/Receive Test Pattern
Self Test Z Check Internal Components (Resets Unit)
Exit Test &T0 Stops test, returns to data mode
TD = Customer Transmit Data
RD = Customer Receive Data
TX = Network Transmit Data
RX = Network Receive Data
The test patterns shown in Table 12-4 are available for the DTE with Test Pattern
and Test Pattern tests.