Elseta WCC Lite, Руководство пользователя, Страница: 121 / 160

•
Usage of last value
. Decision if last value for a signal should be used if a new value of a signal
is not a number (NaN) or contains a non­topical (NT) flag;
•
Limiting of values
. If a value exceeds a lower or higher configured limit, value is approximated
not be lower (or higher) than the limit. An additional invalid (IV) or overflow (OV) flag is added
as frequently used in IEC­60870­5 protocols;
• Suppresion of values . As electrical circuits can be noisy, protocols may generate multiple values
in a short amount of time. What is more, some values are considered as intermediary and
ideally should not be sent to SCADA unless they stay in the same state for some amount of time.
suppression_values
and
suppression_time_ms
are used to configure this functionality;
•
Treshold checking
. If a new signal doesn’t cross a threshold target value, value is
supressed and not used in further stages.
absolute_threshold
,
integral_threshold
,
integral_threshold_interval
,
threshold_units
columns are used to configure this functionality.
Not all of the elements in this sequence have to configured, missing operation are skipped and
values are fed to a further stage of signal recalculation.
17.2.4 number_type field
This field is required for some protocols to determine a method to retrieve a signal value from
hexadecimal form. Available values:
• FLOAT ­ 32­bit single precision floating point value according to IEEE 754 standard
•
DOUBLE
­ 64­bit double precision floating point value according to IEEE 754 standard
•
DIGITAL
­ 1­bit boolean value
• UNSIGNED8 ­ 8­bit unsigned integer (0 ­ 255)
•
SIGNED8
­ 8­bit signed integer (­128 ­ 127)
•
UNSIGNED16
­ 16­bit unsigned integer (0 ­ 65535)
• SIGNED16 ­ 16­bit signed integer (­32768 ­ 32767)
•
UNSIGNED32
­ 32­bit unsigned integer (0 ­ 4294967295)
•
SIGNED32
­ 32­bit signed integer (­2147483648 ­ 2147483647)
• UNSIGNED64 ­ 64­bit unsigned integer (0 ­ 18446744073709551615)
•
SIGNED64
­ 64­bit signed integer (­9223372036854775808 ­ 9223372036854775807)
Number conversion uses
big endian
byte order by default. Converted data will be invalid if byte
order on connected device side is different. In such case byte swap operations can be used. Adding
swap prefixes to number type will set different a byte order while converting values. Following swap
operations are available:
•
SW8
­ Swap every pair of bytes (8 bits) (e.g.,
0xAABBCCDD
is translated to
0xBBAADDCC
)
• SW16 ­ Swap every pair of words (16 bits) (e.g., 0xAABBCCDD is translated to 0xCCDDAABB )
•
SW32
­ Swap every pair of two words (32 bits) (e.g.,
0x1122334455667788
is translated to
0x5566778811223344
)
120