Patton electronic 2500 Series LAL Test Procedure, Remote Digital Loopback RDL, RDL Test Procedure

LAL Test Procedure

Once LAL is activated, the Model 2500 Series transmit output is connected to its own receiver. The “Test” LED should be lit. Follow these steps to complete the test:

1)Verify that the data terminal equipment is operating properly and can be used for a test. If a fault is indicated, call a technician or replace the unit.

2)Perform a BER (bit error rate) test on each unit using a separate BER tester (The Model 2500 Series has a built-in BER tester–see Section 5.4). If the BER test equipment indicates no faults but the data terminal indicates a fault, follow the manufacturer's checkout procedures for the data terminal. Also, check the interface cable between the terminal and the Model 2500 Series.

5.3.2REMOTE DIGITAL LOOPBACK (RDL)

The Remote Digital Loopback (RDL) test checks the performance of both the local and remote Model 2500 Series',and the communication link between them. Any characters sent to the remote Model 2500 Series in this test mode will be returned back to the originating device. For example, characters typed on the keyboard of the local terminal will appear on the local terminal screen after having been passed to the remote Model 2500 Series and looped back (see Figure 7, below).

Figure 7. Remote digital loop

RDL Test Activation

The RDL test may be activated in one of three ways:

1)Toggle the front panel “Local/Normal/Remote” switch DOWN to the “Remote” position.

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2)Activate the RL lead from the DTE (Note: in order to use this option, the DTE Loop Control option must be enabled–see Section 4.1.2). If you are not sure which pin is the RL lead, please

refer to the pinout diagrams in Appendix D.

3)From a terminal, first go to the Main Menu and select item 3 to display the Software Switch Menu (Section 4.2) In the Software Switch Menu, select item “d” to go to the Set Remote Digital Loop Menu (see below). To activate RDL, select item 1.

RDL Test Procedure

Once LAL is activated, the “Test” LED should be lit. Perform a BER (bit error rate) test on the system, using BER testers on both ends. If the BER test equipment indicates a fault and the Local Analog Loopback test was successful for both Model 2500 Series units, you may have a problem with the line between the CSU/DSUs. You should inspect the line for proper connections.

5.3.3 TELCO TESTING

The digital service provider’s central office can perform CSU Loop and DSU Loop diagnostic testing. These diagnostics allow the central office to evaluate circuit operation without making visits to a customer’s premises.

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