ER | glows red to indicate the likelihood of a Bit Error |
| in the received signal. During the 511 or 511/E |
| test, ER flashes to indicate that the Test Pattern |
| Detector has detected a bit error. |
TM | glows yellow to indicate that the Model 1092ARC |
| has been placed in Test Mode. The unit can be |
| placed in test mode by the local user or by the |
| remote user. |
NS | (No Signal) glows red to indicate that the local |
| Model 1092ARC has not yet connected with the |
| remote Model 1092ARC. |
5.2 TEST MODES
The Model 1092ARC offers two proprietary loopback test modes, plus a
5.2.1 Local Line Loopback (LLB)
The Local Line Loopback (LLB) test checks the operation of the local Model 1092ARC, and is performed separately on each unit. Any data sent to the local Model 1092ARC in this test mode will be echoed (returned) back to the user device (see Figure 12, below). For example, characters typed on the keyboard of a terminal will appear on the terminal screen.
LLB initiated
Figure 12. Local Line Loopback
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To perform an LLB test, follow these steps:
1.Activate LLB. This may be done in one of three ways:
-Move the front panel toggle switch to the right to “Local”.
-Raise the LLB signal on the interface (see Appendix B).
-Set Local Loop from the VT100 screen.
Once LLB is activated, the Model 1092ARC transmitter output is connected to its own receiver. Data is also looped back to the line. The “TM” LED should be lit.
2.Verify that the data terminal equipment is operating properly and can be used for a test.
3.Perform a V.52 BER (bit error rate) test as described in Section 5.2.3. 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 1092ARC.
5.2.2Remote Digital Loopback (RDL)
The Remote Digital Loopback (RDL) test checks the performance of both the local and remote Model 1092ARCs, and the communication link between them. Any characters sent to the remote Model 1092ARC in this test mode will be returned back to the originating device (see Figure 13, below). 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 1092ARC and looped back.
Local 1092ARC |
| Remote 1092ARC |
|
|
|
|
|
|
RDL initiated
Figure 13. Remote Digital Loop
Important! Do not send a 511 test pattern from the test equipment when you connect external test equipment to the 1092ARC .
To perform an RDL test, follow these steps:
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