Rockwell Automation FactoryTalk Scheduler Users Guide - Manual (Page 36)

F ACTORY T ALK S CHEDULER U SER ’ S G UIDE
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all operations with lower root numbers and a fewer number of suffixes must
precede that operation, as long as the remaining suffixes match,
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all operations with lower root numbers and the same suffixes, but with additional
appended suffixes must precede that operation, and
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the converse defines the operations that succeed that operation.
The immediate successor operation(s) scheme
The operation number in the immediate successor operation scheme does not include any
sequence information. The sequence of operations is determined by specifying an
additional operation field, called the immediate successor operation attribute. The rules
for this scheme are:
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each operation in a routing must have a unique job step number,
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the operation numbers cannot include suffixes,
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the immediate successor operation attribute field defines the immediate successor
operation job step number,
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if an operation has no successor, the immediate successor operation attribute field is
left blank, and
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if an operation has multiple successors, the job step numbers are separated by the “&”
character.
Sequencing constraint examples
A set of examples will best explain these rules and illustrate the differences between the
two schemes. In the following examples, we include both a routing diagram to illustrate
the operation sequence numbering scheme and a successor table to illustrate the
immediate successor operation scheme. In most of the examples, the operation numbers
will be different. In those examples, both operation numbers will be displayed in the
routing diagrams, with the immediate successor operation numbers in parentheses “( )”.
Both operation numbers will also be included in the successor table. The operation
sequence numbering scheme operation numbers will be labeled as OSN scheme operation
number, and the immediate successor operation scheme operation numbers will be labeled
as ISO scheme operation numbers.
If you have simple straight-line routings with no assembly or disassembly, then you only
need to use root operation numbers. You can also describe one operation assembly or
disassembly routing using only root operation numbers. Our first example shows two
parallel operations, labeled 10, which can be performed independently, but both need to
be completed before the last operation, labeled 20, can be started.