Protocol analysis
R&S
®
RTO6
560
User Manual 1801.6687.02 ─ 05
"= (equal)"
The
equal
operator (represented by the "=" sign) defines a pattern for
the field to match. Valid condition entries are characters that match
the cell's defined "Format", "Bit order", and "Bits". In binary format, for
example, valid characters are "1", "0", "H" (high), and "L" (low).
Three cases
have to be distinguished (cases A, B1, and B2),
depending on the presence of a
frame description:
●
Case A
: If there is
no
"Variable Length Array" field, then each
field marked with the equal operator acts as a key to identify a
frame type. Only if all these fields match up with the expected
value, the frame type is identified.
●
Cases B1 and B2
: If there
is
a "Variable Length Array" cell, then
the equal operator has two different functionalities, depending on
the position of the equal-operator cell within the frame description:
–
B1
: If the cell is located
anywhere before
the "Variable Length
Array" cell, the condition acts as a key to identify a frame type
(as in case A).
–
B2
: If the cell is located
immediately after
the "Variable Length
Array" cell, the condition acts as an array delimiter.
(Note: If the cell, which is marked with the equal operator, is
located after the "Variable Length Array" cell, but
not
immedi-
ately after it, the decode result is unpredictable.)
Typically, Manchester protocols use code violations for synchroniza-
tion. The states "H" and "L", supported by the equal operator in binary
, mark that a transition is expected at this bit, but only a high
or low signal is found.
Examples for the MVB protocol:
Master - Delimiter: "
=1LH0LH000
"
Slave - Delimiter: "
=0000LH0LH
"
For more details on the violation symbols "H" and "L", see
ter 13.6.1.1, "Special features of Manchester coding"
Also, the length of the pattern must correspond to the bit field length
(or the results are unpredictable).
Custom: Manchester / NRZ (option R&S
RTO6-K510)
