Rockwell-automation FactoryTalk Scheduler Users Guide Manual do Utilizador descarregar pdf (Página 50)

FACTORYTALK SCHEDULER USER’S GUIDE

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as an available ranking order property. FactoryTalk Scheduler will automatically list

all specified order properties.

 Priority: Ranking based on the smallest numeric priority. If you use this rule, a

priority field must be included in the order database.

 Process Time: Ranking based on the sum of the job’s operation times, the smallest

sum being ranked first.

 Release Date: Ranking based on the earliest job release (or early start) date first.

 Reverse Priority: Ranking based on the largest numeric priority. If you use this rule, a

priority field must be included in the order database.

 Slack Time: Ranking based on the smallest total job slack time.

 User Rule: Ranking based on a custom-written user rule. Multiple user rules can be

added with the name of each display on a secondary selection list.

Simulation-based sequencing

Simulation-based sequencing provides an attractive alternative to algorithmic

sequencing by providing a simple, yet very flexible method for constructing a schedule. In

general, any schedule that is produced by an algorithmic sequencer can also be produced

by a simulation-based sequencer. A simulation-based sequencer, however, can also

consider many schedules that cannot be considered by an algorithmic sequencer.

In contrast to the algorithmic sequencer, the simulation-based sequencer selects and loads

an operation-at-a-time. By loading individual operations rather than entire jobs, the

simulation-based sequencer has finer control over the way the operations are loaded onto

the planning board. This operation-at-a-time loading is the key to the added flexibility in

schedule generation using the simulation-based sequencer.

A second fundamental difference between the algorithmic and simulation-based

sequencer is that the simulation-based sequencer constructs the schedule in a single time

pass by moving forward from one event time to the next. The simulation-based sequencer

begins at the current time and loads all operations that can start now. Note that these

operations do not come from a single job as in the case of the job-at-a-time sequencer, but

can be taken from the entire set of jobs. Once all operations are loaded that can start at this

event time, the simulation-based sequencer advances time to the next event—e.g., the first

completion time for any operation on the planning board. In this case, a busy resource has

just changed to idle; hence, the simulation-based sequencer attempts to load additional

operations at this new event time. The simulation-based sequencer continues in this

fashion, advancing time forward to the next event time and loading additional operations

as resources become idle, until all operations have been loaded.

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Rockwell-automation FactoryTalk Scheduler Users Guide Manual do Utilizador Página 50