CPU Memory

3 types of memories are available in a BMEP58•••• CPU:

  • non-persistent application RAM: run the application program and store temporary data

  • flash memory: back up the application program and a copy of %MW values

  • optional SD memory card: store application and data in parallel to the CPU flash memory, allowing a fast CPU hardware replacement

Application Download to the CPU Memory

CPU memory involved during an application download from a programming terminal:

  • Application is transferred into the non-persistent application RAM.

  • If a memory card is inserted, working and not write protected, then an internal backup is performed in the memory card.

  • The application backup is performed in the the flash memory.

NOTE: A write protected memory card inserted disables the application download.

Application Upload from the CPU Memory

The application upload reads and copies non-persistent application content from RAM to your selected location.

Application Online Modification Backup

An application program modification is performed in the CPU non-persistent memory with an automatic backup performed as follows:

  • If a memory card is inserted, working and not write protected, then the backup is performed in the memory card.

  • The application backup is performed in the flash memory.

NOTE: The online modification is disabled when a write protected memory card is inserted.

Application Memory Self Modification

The user code may modify the application content (for example to save I/O parameters or replace variables initial value by the current value).

In such a case, only the non-persistent application RAM content is modified.

To back up the application in the memory card and to the flash memory, use the system bit %S66.