Optimizing Performance

  • Logix controllers are optimized for the DINT and REAL data types. Use these data types to avoid conversion overhead and optimize performance.
  • You can optimize the communication performance of acquiring data from Logix controllers by consolidating multiple data values into a User-Defined Type (UDT) or array.
  • Indexed references to array elements add additional scan time overhead to the application. Use single dimension arrays whenever possible.
  • Reserve 20% or more of the controller's memory to accommodate communications and changes in future Logix controller firmware releases.
  • Use rack optimized communication formats for digital I/O modules to minimize amount of controller memory and communications overhead associated with these modules.
  • Use the CPS instruction to provide buffering of communications and I/O data to minimize impact of asynchronous data arrival.
  • If the memory estimation button is disabled, it means that your estimation is up to date. This happens after an estimate, but it also happens when you go offline with the controller because the offline memory numbers reflect actual use.
  • The order of members within a User-Defined Type (UDT) affect the memory size of the data type. Within the UDT, keep members of the same data type together.

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