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Everything you Need to Know About 429 Scheduler

When scheduling ARINC 429 traffic, having fine control of sending the messages greatly simplifies your application.

For instance, having the ability to send one or more messages using a FIFO based scheduler greatly simplifies your application.

But, when you need a more complex pattern of commands, you need a very capable scheduler. You should have one that gives you fine grain control for system level communications.

There are multiple ways to define a label schedule. A simple yet powerful approach is to treat the label scheduler as one big label table, augmented with control flags:

Dependent Entries - Have Entries that are dependent on a Master Entry.

Time Delay - A countdown of how many scheduler iterations to wait till this command is sent.

Recycle Flag – This flag tells the scheduler to only run this entry once or repeat it every cycle.

Finished Flag – tells the application that this entry was sent. Now is the time to replace or update this particular command.

Time Bases - Have different time bases so that entries can be sent at different frequencies.

For instance, you should be able to set up a scheduler to…

  • Send a Master Entry once and only once.
  • Send a Master Entry without dependent entries at 10kHz
  • Send a Master Entry without dependent entries at 5kHz
  • Send a Master Entry without dependent entries at 2kHz
  • Send a Master Entry with Dependent Entries where 1 of the 3 Dependent Entries is only transmitted the third time the Master Entry is transmitted.
  • Notify you when an entry is transmitted.

Learn more about ARINC 429 in this tutorial page.