Hello,

i am looking for information about persistent variables. I made a program which declare some persistent variables. Everything work fine and when the device shutdown and restart, the variable are indeed persistent in the right way. When i change the program (not the PersistentVars) and upload the new program to the device, the persistent variables are not restored as expected : not always, depending on the modification i made to the programe.
I had try a lot a things but do not understand why when i made a change to the program, sometime the persistent variables restart from 0 (persistent lost) and sometime the persistent variables keep its latest value. When exporting in OpenXML, i saw that sometimes tags "Checksum_Type" and "checksumnoinit_override" are added.

Does someone can help me understand if this behaviour is correct or not ? Does someone know the meaning of the tag "Checksum_Type" and "checksumnoinit_override" ?

      <globalVars name="PersistentVars" retain="true" persistent="true">
        <variable name="_A">
          <type>
            <DINT />
          </type>
          <initialValue>
            <simpleValue value="0" />
          </initialValue>
          <addData>
            <data name="http://www.3s-software.com/plcopenxml/attributes" handleUnknown="implementation">
              <Attributes>

<attribute name="Checksum_Type" value="3401061445"></attribute>




<adddata>
<data handleunknown="implementation" name="http://www.3s-software.com/plcopenxml/attributes">
<attributes>
<attribute name="checksum_override" value="2196742183"></attribute>
<attribute name="authentification" value="d433c4d1-208a-4b7a-b4ba-e3c77e67e46b">
<attribute name="vfinitonly" value="">
<attribute name="dummy" value="0">
<attribute name="checksumnoinit_override" value="2363421397"></attribute>
</attribute></attribute></attribute></attributes>
</data>
</adddata>