I'm having problems with using the "AppStoreRetainsInFile" function. specificity using the function in a program with multiple applications. when I use it on the main application it works and returns 0 in the result tag. but when I use it on one of the child application it doesn't seem to work and return 2. What does the return code mean? does it correspond to the table in the "CmpErrors2 interfaces" library? then it means "Invalid parameter for this operation" but I can't figure out what I am doing wrong.

here is the test version of the code I'm trying to run. it is based on the application manager program example found on CoDeSys forge.

VAR
    fbDelete            : FILE.Delete; (* Function block to delete the file *)
    (* The retain file <application-name>.ret is placed in the directory of the bootproject *)
    sFileName           : STRING := 'Mod3.ret';
    pApp                : POINTER TO APPLICATION;
    Result              : RTS_IEC_RESULT; (* Result code *)
    Result2             : RTS_IEC_RESULT; (* Result code *)
    Result3             : RTS_IEC_RESULT; (* Result code *)
    Result4             : RTS_IEC_RESULT; (* Result code *)
    xInit               : BOOL;
    test1               : BOOL;
    test2               : BOOL;
    test3               : BOOL;
    test4               : BOOL;
    teststring          : string;
END_VAR

(* The retain variables are stores in a file and get retrieved afterwards. *)
IF NOT xInit AND test1 THEN

    (* First delete the retain file.
       This is necessary, because the function AppStoreRetainsInFile appends the data at the end of the file. *)
    fbDelete(xExecute:=TRUE, sFileName:=sFileName);
    IF fbDelete.xDone OR (fbDelete.xError AND fbDelete.eError = FILE.ERROR.NOT_EXIST) THEN
        (* Attention: It takes at least one cycle until xDone is TRUE *)
        fbDelete(xExecute:=FALSE);
        xInit := TRUE;
        (* Now, it's the time to save the retains. *)
        pApp := AppFindApplicationByName('Mod2', ADR(Result));
        IF pApp <> 0 THEN
            (* Store the variables in a file*)
            Result2 := AppStoreRetainsInFile(pApp,sFileName);
        END_IF
    END_IF
END_IF

(* Restore the Retain Variables from the file.
   For storing and restoring, the same pointer to application (pApp) must be used.*)
IF test2 THEN   
    Result3 := AppRestoreRetainsFromFile(pApp, sFileName);
    test2 := FALSE;
END_IF;

If I change the string in the "AppFindApplicationByName" function to 'Site' and change the sFileName to 'Site.ret' it works and the "AppStoreRetainsInFile" returns 0. this is my main application. in that application I have 4 child applications. Mod2, Mod3, Mod4 and Mod5. if I do the same with them the "AppStoreRetainsInFile" function returns 2. It should not a problem with the "AppFindApplicationByName" function because it successfully finds the pointer to the application.

is there any documentation about the CmpApp library? What does the 2 mean? thanks in advance!

Hi Patrik,

Did you get everything working?
I have been trying to get it to work but doesn't seem to be working correctly for me.
It returns 0 saying everything was fine and no errors but does not seem to save the retain value when I restart the CodeSys runtime or with power loss the retain value is not restored and the old value from a correct shutdown is returned.

Thanks,
Matthew

Hello!
sorry about the late answer.

I have not gotten it to work yet. however it sounds like it is working for you. if the function returns 0 then it should mean that it works. To get the saved values back you have to use the "AppRestoreRetainsFromFile" function as far as I know. Try using that.

Hi Matthew!

If I interpret the code right. The example from the ApplicationManager program saves the persistant to a file when it detects "firstscan". This is not what I want of the program and I think it's not the function you are looking for either. I wan't it to run the restore from file when it detects that persistant vars has been lost. I've made it so my program tries to save to file each 10 sec or so. that way the data should be quite fresh when I want to restore from file. If this is a good way to do it or even the right way, I don't know.

Hi,
I try to explain, the persistence/retain feature:
Usually if you do nothing in your application and you shutdown your plc graceful( not just poweroff), this means Linux shutdown or - you have for example a UPS connected, Application.ret will be written by tthe runtime, no need to call anything.
on next restart the Application.ret will be loaded with the bootproject on startup.
This is how retains in generell work.

Now if you trigger this 'save retains' from the application to application.ret it might that these interact with the in background working feature.
Try to save the retains with another name.ret, and recover them on startup of your application.

Altough the proper solution is to have a UPS and a graceful shutdown. Then no need to do anything with this function and additional you protect your OS against damage on the SD card/flash, makes it more robust against the ' I could not start my OS because filesystem is corrupt' problem.

Have problem with AppStoreRetainsInFile, AppRestoreRetainsFromFile function. All time return
ERR_OPERATION_DENIED.
Maybe need add something in Codesys Config file (/etc/CODESYSControl_User.cfg) to make it accessible ? Using ARM SL 4.7.0.0 Runtime.

I think you need use file placeholders ($$PlcLogic$$/Application/...) instead of direct filepath.

yes thanks this is help.