C0244: warning when using persistent variables in FB

2020-02-27T14:21:46.103000Z

MaraP hat geschrieben:
Also I don't how VAR PERSISTENT RETAIN works. Usually I declare them as VAR RETAIN or as VAR PERSISTENT

In Codesys V2.3 VAR RETAIN PERSISTENT kept the variable in more scenarios than just persistent or just retain.
In Codesys V3, VAR PERSISTENT is treated the same as VAR PERSISTENT RETAIN.

Codesys V2.3 Remanent variables:
x = value will be retained - = value gets reinitialized

+--------------------+---+----------+--------------+---------------------+
|after Online command|VAR|VAR RETAIN|VAR PERSISTENT|VAR RETAIN PERSISTENT|
|                    |   |          |              |VAR PERSISTENT RETAIN|
+--------------------+---+----------+--------------+---------------------+
|Reset               | - | x        | -            | x                   |
+--------------------+---+----------+--------------+---------------------+
|Reset cold          | - | -        | -            | -                   |
+--------------------+---+----------+--------------+---------------------+
|Reset origin        | - | -        | -            | -                   |
+--------------------+---+----------+--------------+---------------------+
|Download            | - | -        | x            | x                   |
+--------------------+---+----------+--------------+---------------------+
|Online Change       | x | x        | x            | x                   |
+--------------------+---+----------+--------------+---------------------+

Codesys V3.x Remanent variables:
x = value will be retained - = value gets reinitialized

+--------------------+---+----------+--------------+---------------------+
|after Online command|VAR|VAR RETAIN|VAR PERSISTENT|VAR RETAIN PERSISTENT|
|                    |   |          |              |VAR PERSISTENT RETAIN|
+--------------------+---+----------+--------------+---------------------+
|Reset warm          | - | x        | x            | x                   |
+--------------------+---+----------+--------------+---------------------+
|Reset cold          | - | -        | x            | x                   |
+--------------------+---+----------+--------------+---------------------+
|Reset origin        | - | -        | -            | -                   |
+--------------------+---+----------+--------------+---------------------+
|Download            | - | -        | x            | x                   |
+--------------------+---+----------+--------------+---------------------+
|Online Change       | x | x        | x            | x                   |
+--------------------+---+----------+--------------+---------------------+

You will note also that V3 does not reset presistent variables on reset cold.

C0244: warning when using persistent variables in FB

2020-02-27T14:21:45.666000Z

I would declare persistent variable outside function block. You can declare your current variable as VAR_IN_OUT and then put your persistent variable to this input. Also I don't how VAR PERSISTENT RETAIN works. Usually I declare them as VAR RETAIN or as VAR PERSISTENT

C0244: warning when using persistent variables in FB

2020-02-27T14:21:45.159000Z

Hello,

I have a FB with PERSISTENT RETAIN variables.
I cannot seem to get the instances of this FB into the persistentVars list without C0244 warnings.

Has anyone solved this? Do you just live with the warnings?

Codesys V3.5 SP13 Patch 2 + (64-Bit)

Below is the code and a copy of the warning message

///Retentive Timer
///If you wish to retain the value after a reboot, 
///put the FB instance in a PERSISTENT VARIABLES LIST
FUNCTION_BLOCK RTO
VAR_INPUT
   In : BOOL;
   Reset : BOOL;
   PT : LTIME;
END_VAR
VAR
    FirstScan: BOOL := TRUE;
    Previous_Time: LTIME;
    Current_Time: LTIME;
END_VAR
VAR PERSISTENT RETAIN
   internalET : LTIME;
END_VAR
VAR_OUTPUT
   Q : BOOL;
   ET : LTIME;
END_VAR
Current_Time := LTIME();  //LTIME() Produces the current system time in ns
IF FirstScan THEN //If the controller has been reset
   Previous_Time := Current_Time;
   FirstScan := FALSE;
END_IF
IF Reset THEN
   internalET := LTIME#0NS;
ELSIF In AND NOT (ET >= PT) THEN
   internalET := internalET + Current_Time - Previous_Time;
END_IF
Q := (internalET >= PT);
ET := internalET;
Previous_Time := Current_Time;

PROGRAM Main
VAR PERSISTENT RETAIN
   me : RTO;
END_VAR

{attribute 'qualified_only'}
VAR_GLOBAL PERSISTENT RETAIN
   
   // Generated instance path of persistent variable
   Main.me.internalET: LTIME;
   // Generated instance path of persistent variable
   Main.me: RTO;
END_VAR

Zitat:
[WARNING] Untitled2: RTO CODESYS: PLC Logic: Application: C0244: No matching instance path in VAR_PERSISTENT-list found for variable PersistentVars.__m1.internalET. Use the command "Add all instance paths" to add all instance paths to the VAR_PERSISTENT-list. (see Online help for details).

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