7.19
Date Code 20120126 Instruction Manual SEL-2032 Communications Processor
Settings
Automatic Message (SET A) Settings
If an invalid character is read before any valid characters, then the parse rule
fails and the data element is reset.
If an invalid character is found after at least one valid character, the current
Decode Element is valid and evaluation of the next element starts.
If all the Decode Elements within a Decode Expression fail, or the message
collection times-out, then all the remaining data elements referenced in the
Decode Equation are reset to the values listed in Table 7.4.
Parsing Precedence
Parsing is evaluated from left to right according to the Decode Equation.
However, special rules apply to Search Strings using a preceding ampersand.
This type of Search String is referred to as an ampersand Search String in the
text below.
If a Search String is the first expression in the Decode Equation, then the
parser searches for the Search String in the message. Once the Search String is
found, evaluation of the Decode Equation proceeds.
The ampersand Search String has the highest precedence. If a Decode
Equation contains a Search String, and the Search String is found before the
completion of the previous Decode Expression, the Decode Expression has
failed and all remaining elements in the Decode Expression are reset (see the
reset values in Table 7.4).
If the incoming string contains data that is both valid for the specified data
type, and matches the ampersand Search String, the Search String has
precedence. If the incoming data only contains the Search String, then the
previous Decode Expression is reset.
The ampersand Search String is evaluated with the preceding Decode
Expression. A Search String with a preceding comma is evaluated in the order
it appears in the Decode Expression.
EXAMPLE 7.1 Parsing Precedence Examples
I, F, H& ‘str’ The parser watches for ‘str’ while evaluating for the H
element. If ‘str’ is found before the H element, then H is reset.
I, (F, H)& ‘str’ The parser watches for ‘str’ while evaluating for
both the F and H elements. If ‘str’ is found while evaluating F,
both F and H are reset.
2{I, (F, H)}& ‘str’ In this case, because the ‘str’ is outside the
brace, the ‘str’ is only searched for on the very last element of
the array. To evaluate ‘str’ for each row of the array, move ‘str’
inside the brace.
I, H, ‘str’, F The parser evaluates the incoming data for Integer
and Hex and then parses the data until ‘str’ is found. After ‘str’
is found, the parser evaluates the next floating point. If H is not
found and ‘str’ is found, processing continues for F.
Courtesy of NationalSwitchgear.com
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