PEB2080 SIEMENS [Siemens Semiconductor Group], PEB2080 Datasheet - Page 34

• Manufacturer Part Number: PEB2080
• Description: S/T Bus Interface Circuit(SBC)
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Functional Description
2.5
Additional Functions
Test Functions
Test loops
Two kinds of test loops may be closed in the SBC, which depend on the selected mode of operation.
In both test loops, all three channels (B1, B2 and D) are looped back. In a “transparent loop” the
data are also sent forward (in addition to being looped back), whereas in a “non-transparent loop”
the forward data path is blocked (CCITT I.430). These test loops are shown in figure 17.
Figure 17
Test Loops of SBC
Test loop 3 is activated with the C/l channel command Activate Request Loop (ARL). An S interface
is not required since INFO3 is looped back to the receiver. When the receiver has synchronized
itself to this signal, the message “Test Indication’’ (or “Awake Test Indication”) is delivered in the C/l
channel. No signal is transmitted over the S interface.
Test loop 2 is likewise activated over the IOM interface with Activate Request Loop (ARL). No S line
is required. INFO4 is looped back to the receiver and also sent to the S interface. When the receiver
is synchronized, the message “AIU” is sent in the C/l channel. In the test loop mode the S-interface
awake detector is disabled, and echo bits are set to logical “0”.
Semiconductor Group
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