Black Box ME445C-35, ME444AE-R3, ME445C-X.21, ME444A-R3, ME445C-530 manual Remote Digital Loopback

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CHAPTER 6: Troubleshooting

6.5 Remote Digital Loopback

Activate the remote digital loopback test by pressing the REM button or by raising the level of the remote loopback signal received by the line driver’s V.35 connector (Pin HH). This test involves creating an outbound loopback at the remote line driver (see Figure 6-5 on the next page). The test checks the performance of the local and remote units and the line between them:

1.Press REM or raise remote loopback; the local line driver will signal the remote unit to start remote digital loopback. The TEST LED should light on both units. The remote line driver’s receive input should be connected to its own transmitter.

2.Perform a Bit Error Rate Test (BERT). Either:

Hook up an external Bit Error Rate Test (BERT) unit in place of the local DTE; or

Use the local line driver’s internal BERT. Press the PATT button. The ERR LED should light briefly just to confirm that the LED is working, and then the test will proceed. If errors are detected, the ERR LED will be continuously lit (if the errors are continuous) or will blink (for intermittent errors).

3.If the BERT test indicates a fault, but both line drivers pass their modem self- tests, there is a problem somewhere in the communication line between the units.

4.After the test is complete or the fault has been corrected, restore the REM button to its normal position. Proceed with local digital loopback.

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Contents Kbps Line Driver FCC and IC RFI Statements Safety Warnings Declaration of Conformity Kbps Line Driver V.35, RS-530, or NOM Statement Trademarks Used in this Manual Contents Specifications Flow Control NoneSpecifications Introduction Physical DescriptionLine driver block diagram Functional DescriptionModulation Timing Applications Point-to-point applicationTail-circuit application Installing the Card Version in the RackNest 2/14 ConfigurationPlacement of the Standalone Version Description of the Racknest 2/14’S Power Supply Configuring the Standalone or Card Version User-configurable optionsUser-configurable options Layout of the 256-kbps Line Driver circuit board Kbps Line Driver V.35, RS-530, or Installation Installing the Standalone Version in 19-Inch RacksInstalling a single unit in a 19-inch rack Installing two units in a 19-inch rack Installing the 256-kbps Line Driver Rackmount Card Version Installing a card in the RackNest 2/14RackNest 2/14 illustrated Function Installation Kbps Line Driver V.35, RS-530, or Signal ITU-TSS Lead Name Abbrev Circuit Type Rack Norm Nest PIN Pinout of the V.35 standalone’s M/34 connector DB25 DA15 Connecting Data Cables Line Connection Installation Controls and Indicators OperationOperation Operating Procedure IndicatorsLoop Tests TroubleshootingBit-Error-Rate Tester Bert Bert using loops Modem Self-Test Local Analog LoopbackLocal analog loopback Remote Digital Loopback Local Digital Loopback Remote digital loopbackCalling Black Box Local digital loopbackShipping and Packaging Appendix Maximum Distances 19-AWG 22-AWG 24-AWG 26-AWG Kbps MilesCopyright 2004. Black Box Corporation. All rights reserved