Protocol analysis
R&S
®
RTO6
561
User Manual 1801.6687.02 ─ 05
"[
] (array)"
The
array
operator (represented by the "[" and "]" bracket signs)
defines the number of permissible repetitions of the cell.
Example: Fixed-Length Array: [n]
The length parameter "n" is a decimal number >
0, which determines
that the cell is repeated n times within the frame. If, for example, the
is 8, then the array operator identifies n cells of 8-bit length, and
present them in the results table and honeycomb display with the
specified name and color.
A fixed-length array is treated the same as other cells, except the real
length of such an array is n
·
bit
count.
Example: Variable Length Array: []
This array operator with empty "[" and "]" bracket signs does not
determine a fixed size array. The cell could be repeated any number
of times, including 0 times. As a result, the cell and the frame are of
unspecified length (a situation that covers typical use cases).
The length of the frame is then determined by the end of frame condi-
tion, which can be an operator or a gap.
For processing reasons, only one (1) variable length array is suppor-
ted in a frame, and a delimiter must follow immediately in the next cell
after it. This is required to enable the software to correctly terminate
the array. Otherwise the bits could not be assigned correctly, and it
would not be possible to determine where a repletion starts and
where it ends. With an end of frame condition, the software can cal-
culate the length of one single array within a frame. But if there were
more arrays, it would be impossible to know which array was how
long.
The variable length array can also be the last cell of a frame. In this
case, no delimiter is required. If decoded successfully, the detailed
view in the results table shows the elements of the array. If the cell
name of the array is "Data", then the detail view of result table dis-
plays the elements with an array index as "Data:
1", "Data:
2" ... etc.
If the variable length array cell is selected, it is shown as array [n],
where n is the actual size detected in the waveform.
As an exception to the rule, it is permissible to assign the variable
length array to consecutive fields. In this case, the fields are treated
as a structure which is repeated. For example, if two consecutive
fields are defined as A[] and B[], the decoder creates a sequence of
ABABAB until the end condition has been detected.
Note:
It is possible to combine check functions in a dynamic array. In
the example above, if B[] is extended by odd(1), with "1" being the
index of A[], then B checks the parity for each index of A.
Custom: Manchester / NRZ (option R&S
RTO6-K510)
