RAD Data comm ASM-20 operation manual Communication Link Tests, Remote Digital Loopback

ASM-20Installation and Operation Manual Chapter 4. Troubleshooting and Diagnostics

Remote Digital Loopback

To check the performance of the local modem and the local data terminal:

1.Press the ANA (Analog Loopback) push button on the front panel (see Figure 3-1). This test can also be activated via the pin on the DTE interface. See Table 2-2for more information. The TEST LED should turn on. ASM-20 transmit output is now connected to its own receiver (see Figure 4-3).

2.Check that the DTE is operating properly and can be used for a test. If a fault is indicated, call a technician or replace the unit.

3.Execute the test using one of the methods described below:

∙Use the DTE and check the echoed data stream

∙Use an external Bit Error Rate Tester (BERT) unit

∙Use the internal Bit Error Rate Tester (BERT). Press the PATT push button. The ERR LED will light up briefly to indicate that the LED is functioning. If any bit error is encountered, the LED will blink or remain ON.

4.Perform Step 3 at both ends. If the BERT test equipment does not indicate a fault, but the data terminal does, follow the manufacturer’s test procedures for the data terminal and check that the cable connecting the terminal and ASM-20 is working. After completion of the test (or when the fault has been corrected), restore the ANA push button to the OFF position by pressing the ANA push button again. Proceed to Communication Link Tests below.

4.7 Communication Link Tests

This test determines the performance of the local and remote ASM-20, and the lines connecting them.

To check the performance of the local and remote ASM-20:

1.Press the REM (Remote Loopback) push button, providing a loopback at the remote ASM-20 (see Figure 4-4). (This test can also be activated via the pin on the DTE interface.) The TEST LED should light up at both the local and remote units.

2.Perform the BERT test using one of the methods described below:

∙Use the DTE and check the echoed data stream

∙Use an external Bit Error Rate Tester (BERT) unit

∙Use the internal Bit Error Rate Tester (BERT). Press the PATT push button. The ERR LED will light up briefly to indicate that the LED is functioning. If any bit error is encountered the LED will blink or remain ON.

Communication Link Tests 4-5