2.5 Persistent memory

REX Control System supports permanent storage of function block parameters and some specified function block internal states. Persistent memory performance is target platform specific. If the target platform does not have any supported persistent memory available, the permanent parameters will be stored to the permem.dat file by default (to the same directory as exec.rex is stored - \rex\rexcore on Linux machines or C:\ProgramData\REXControls\REX_<_version>_\RexCore\).

Persistent memory is internally limited by maximum 2048 bytes per function block (possible problems can come in using long strings).

In order to store the function block parameters, the checkbox Permanent in block properties must be checked - see Fig. 2.2. All function block parameters and some internally selected block states will be stored (excluding arrays). Internally selected block states list:

Default save period is 300 s or the period is inherited from the first hard drive archive if present.

The persistent memory can be reseted or cleaned up using Download Dialog - see Fig. 3.1. Switch Download option in Download Dialog to Expert mode and choose between Reset persistent memory or Cleanup persistent memory. Reset persistent memory will replace entire persistent memory however Cleanup persistent memory will erase just the parameters which are not used any more.

Be aware that the block parameters will be overwritten with the ones stored in persistent memory immediately after swapping executives if the Permanent option is enabled for the function block.