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4.5 Error Detection

4.5.1 Block Basis Error Reporting

For S-LINKs which use cyclic redundancy checking for error detection, errors can only be reported after a block has been transmitted. Errors are therefore only reported with control words. If a block of data is transmitted and an error is detected by the S-LINK, it will set LDERR# low during the cycle containing the next control word. In addition, LD[1] is set low and LD[0] is set high for that word. The data error LED is illuminated and held.

An example of a data stream emerging from an S-LINK which uses block basis error reporting is shown in Table 5. In this example, the block length is four words. In the first block, there is no error. In the second block, an error occurs on the second data word. In the third block, an error occurs on the control word and in the fourth block an error occurs in both the second data word and in the control word.

TABLE 5. Block Basis Error Reporting (in this example the block length is 4 words).
LD[31..4]LD[3..2]LD[1]LD[0]LCTRL#LDERR#
Data Word 111
Data Word 211
Data Word 311
Data Word 411
Control Word (EOB)reserved0001
Data Word 111
Data Word 2 - with error11
Data Word 311
Data Word 411
Control Word (EOB)reserved0100
Data Word 111
Data Word 211
Data Word 311
Data Word 411
Control Word (EOB) - with errorreserved1000
Data Word 111
Data Word 2 - with error11
Data Word 311
Data Word 411
Control Word (EOB) - with errorreserved1100

The S-LINK Interface Specification - 27 MARCH 1997
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