SA0103: Concurrent access on not atomic data

Detects whether or not non-atomic variables (for example, with data type ‎STRING‎, ‎WSTRING‎, ‎ARRAY‎, ‎STRUCT‎, FB instances, 64-bit data types) are used in more than one task

Justification: When there is no synchronization during access, inconsistent values can be read when reading in one task and writing in another task at the same time.

Importance: Medium

For some data types, especially 64-bit integers, it depends on the platform whether or not access is atomic. Static analysis reports a problem only when the controller does not support atomic access to 64-bit integer data types.

This rule does not apply in the following cases:

If the target system has a floating point unit (FPU), then access of multiple tasks to ‎LREAL‎ variables is not detected
If the target system is a 64-bit processor or the corresponding target setting is set for the target device, then the rule does not apply to 64-bit data types

Example

The project contains both programs, ‎PRG1‎ and ‎PRG2‎: The program ‎PRG1‎ is called by the task ‎MainTask_1‎. The program ‎PRG2‎ is called by the task ‎MainTask_2‎.

GVL
VAR_GLOBAL	
	lrTest : LREAL;   // Since the target system has an FPU, SA0103 does apply.
	lint1 : LINT;
	sTest : STRING;   // SA0103
	wsTest : WSTRING; // SA0103
END_VAR

PROGRAM PRG1
GVL.lrTest := 5.0;
GVL.sTest := 'welt';
GVL.wsTest := "welt";
GVL.lint1 := 99;

PROGRAM PRG2
GVL.lrTest := 5.0;
GVL.sTest := 'hallo';
GVL.wsTest := "hallo";
GVL.lint1 := 88;

--> SA0103: Concurrent access on not atomic data 'sTest'
--> SA0103: Concurrent access on not atomic data 'wsTest'