Campbell Scientific CR5000 Measurement and Control Module - Manual (Page 100)

Section 6. Data Table Declarations and Output Processing Instructions
6-6
WorstCase (TableName, NumCases, MaxMin, Change, RankVar)
Allows saving the most significant or “ worst-case” events in separate data
tables.
A data table is created that is sized to hold one event. This table acts as the
event buffer. Each event that occurs is stored to this table. This table may use
the DataEvent instruction or some other condition to determine when an event
is stored. The significance of an event is determined by an algorithm in the
program and a numerical ranking of the event is stored in a variable.
WorstCase creates as many clones of the specified table as the number of cases
for which to keep data. When WorstCase is executed, it checks the ranking
variable; if the value of the variable is a new worst case, the data in the event
table replace the data in the cloned table that holds the least significant event
currently stored.
An additional data table, nameWC (e.g., EvntWC) is created that holds the
values of the rank variables for each of the worst case tables and the time that
that table was stored.
WorstCase must be used with data tables sent to the CPU. It will not work if
the event table is sent to the PC card.
While WorstCase acts as Trigger Modifier and a data table declaration
(creating the cloned data tables), it is entered within the program to call the
worst case tables (see example).
Parameter
& Data Type Enter
TableName
name The name of the data table to clone. The length of this name should be 4 characters or
less so the complete names of the worst case tables are retained when collected (see
NumCases).
NumCases The number of “ worst” cases to store. This is the number of clones of the data table to
create. The cloned tables use the name of the table being cloned (up to the first 6
characters) plus a 2 digit number (e.g., Evnt01, Evnt02, Evnt03, …). The numbers give
the tables unique names, they have no relationship to the ranking of the events. PC9000
uses this same name modification when creating a new data file for a table. To avoid
confusion and ambiguous names when collecting data with PC9000, keep the base name
four characters or less (4character base name + 2 digit case identifier + 2 digit collection
identifier = 8 character maximum length).
MaxMin A code specifying whether the maximum or minimum events should be saved.
Constant Value Result
0 Min, save the events associated with the minimum ranking; i.e.,
Keep track of the RankVar associated with each event stored.
If a new RankVar is less than previous maximum, copy the
event over the event with previous maximum)
1 Max, save the events associated with the maximum ranking;
i.e., copy if RankVar is greater than previous lowest (over event
with previous minimum)
Change
Constant
The minimum change that must occur in the RankVariable before a new worst case is
stored.
RankVar
Variable
The Variable to rank the events by.