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Index Registers Section 6-2
Table Processing (Range Instructions)
The range instructions act on a range of words, which can be considered a
table of one-word records. These instructions perform basic operations such
as finding the maximum value or minimum value in the range, search for a
particular value in the range, or calculating the sum or FCS.
The PLC memory address of the result word (word containing the max. value,
min. value, search data, etc.) is automatically stored in IR0. The Index Regis-
ter (IR0) can be used as an operand in later instructions such as MOV(021) to
read the contents of the word or perform other processing.
The following table lists the range instructions and their functions.
The Index Registers can be combined with other instructions (such as com-
parison instructions) in FOR–NEXT loops to perform more complicated opera-
tions on ranges of words.
Table Processing (Record-table Instructions)
The record-table instructions act on specially defined data tables made up of
equal-length records. The records can be accessed by record number for
easy processing.
Note Record numbers and word addresses are related through the Index Regis-
ters. Specify a record number in SETR(635) to store the PLC memory
address of the beginning of that record in an Index Register. When data is
required from the record, add the required offset to that Index Register to
access any word in the record.
Use the record-table instructions with Index Registers to perform the following
kinds of operations: reading/writing record data, searching records, sorting
Range speci-
fied in the
instruction
Max. value
Min. value
SUM calculation
FCS calculation
Search
Data
Instruction Function Description
SRCH(181) Finds search data. Finds the search data in the specified range
and outputs the PLC memory address of the
word containing that value to IR0.
MAX(182) Finds max. value. Finds the maximum value in the specified
range and outputs the PLC memory address
of the word containing that value to IR0.
MIN(183) Finds min. value. Finds the minimum value in the specified
range and outputs the PLC memory address
of the word containing that value to IR0.
SUM(184) Calculates sum. Calculates the sum of the data in the specified
range.
FCS(180) Calculates checksum. Calculates the frame checksum of the data in
the specified range.
Instruction Function Description
DIM(631) Defines a record table. Declares the length of each record and the
number of records.
SETR(635) Sets record location. Writes the location of the specified record (the
PLC memory address of the beginning of the
record) in the specified Index Register.
GETR(636) Gets record location. Returns the record number of the record that
contains the PLC memory address in the
specified Index Register.
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