RAD Data comm ASM-20 operation manual Loop Tests Procedure, Bit Error Rate Tester Bert

Chapter 4. Troubleshooting and DiagnosticsASM-20Installation and Operation Manual

Table 4-1 Differences in Versions (Cont.)

ASM-20	ASM-20-2
Metal box	Plastic box
Terminal block with screws	Clip terminal block
Main chip RJ008 and external	Main chip RJ016 which includes
BERT chip	BERT chip
No CE mark	CE mark
No asynchronous transmission	Asynchronous transmission
	capability

The above versions are compatible with each other within similar synchronous rates.

Additionally, the ASM-20-2 has been improved in order to get a better line surge protection. In many cases line surges are caused by lightening strikes. The improved line protection of ASM-20-2 complies with the ITU-T/K.21 standard.

The line interface has been modified by adding two Gas surge protection diodes and another two Transorber surge protection diodes. The Gas diodes protect against line surges above 300V and the Transorber diodes protect against surges below 300V.

4.3 Loop Tests Procedure

The test switches and LED indicators built into ASM-20 allow rapid checking of the data terminals, ASM-20 and lines. Use the test procedures provided in this chapter to check normal system operation and isolate faulty equipment in the event of failure. Each test verifies the operational performance of a unit in the system or provides a positive indication of equipment failure.

Before testing operation of the data system equipment and line circuits, ensure that all units are turned on and correctly configured.

4.4 Bit Error Rate Tester (BERT)

The Bit Error Rate Tester (BERT) can be activated in any diagnostics test in which the test pattern transmitted is looped back to the BERT for comparison (see Figure 4-1).

4-2 Bit Error Rate Tester (BERT)