PEB2080 SIEMENS [Siemens Semiconductor Group], PEB2080 Datasheet - Page 35

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

Functional Description
Test Signals
Two kinds of test signals may be sent by the SBC: single pulses and continuous pulses.
The single pulses are of alternating polarity, one S-interface bit period wide, 0.25 ms apart, with a
repetition frequency 2 kHz. Single pulses can be sent in all applications. The corresponding C/l
command in TE, LT-S and LT-T applications is SSZ (Send single zeros). Alternatively, this test
mode can be effected by pulling pin SSZ (pin X2, NT mode only) to logical “0”.
Continuous pulses are likewise of alternating polarity, one S-interface bit period wide, but they are
sent continuously. The repetition frequency is 96 kHz. Continuous pulses may be transmitted in all
applications. This test mode is entered in LT- S, LT-T and TE applications with the C/l command
SCZ. Alternatively, pin SCZ (pin CP, NT mode only) can be pulled to logical “0”.
Special Applications
The mode specific pins X0-3 allow for special applications to be implemented, some of which are
mentioned in the following.
Star Configuration
In NT mode, the SBC transmits the D-bit state over pin X0 (DE). A star configuration may be
implemented by connecting pins X0 of several SBC’s together (open drain with integrated pull up).
With X1 (DEX, D-E-External mirrowing) tied to logical “1”, the SBC transmits the resulting DE (wired
AND for all SBC’s) as the S-interface echo bit. See figure 18.
Figure 18
Star Configuration in NT
Semiconductor Group
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