There are two object of User variables type, and the script S1 sets their values:

  • U.Int - integer value
  • U.Text - text representation of the value of U.Int

INT _i
_i := 1
FillNext:
   U.Int := _i
   WAIT
   U.Text := %IToStr(_i)
   WAIT
   _i := _i + 1
 GOTO FillNext
 END
 

The script S2 checks whether the value U.Int is correctly text-represented in the user variable U.Text.


INT _i
TestNext:
   _i := %StrToI(U.Text)
   IF _i # U.Int THEN
     MESSAGE "Not equal" ON WS_BC.HIP
   ENDIF
   GOTO TestNext
 END
 

This arrangement causes the often occurrence of errors. The operation to assign new values to the variables U.Int a U.Text is interrupted by the script S2 which finds incorrect values in them.

The described problem should be solved using the actions GETACCESS a RELEASEACCESS as follows:

Script S1


INT _i
 BOOL _ok
 TEXT _regString = "Access to U.Int"
 _i := 1
 FillNext:
   _ok := GETACCESS _regString ; provide the access
   IF _ok THEN
     U.Int := _i
     WAIT
     U.Text := %IToStr(_i)
     WAIT
     RELEASEACCESS _regString ; release the access      
     _i := _i + 1
   ENDIF
   GOTO FillNext
 END
 

Script S2


 INT _i
 BOOL _ok
 TEXT _regString = "Access to U.Int" 
TestNext:
   _ok := GETACCESS _regString ; provide the access
   IF _ok THEN
     _i := %StrToI(U.Text)
     IF _i # U.Int THEN
       MESSAGE "Not equal" ON WS_BC.HIP
     ENDIF
     RELEASEACCESS _regString ; release the access
 ELSE
   DELAY 100[ms]
  ENDIF
  GOTO TestNext
 END

In such an arrangement, the script S2 accesses to values of the objects U.Int a U.Text only in case its successful text registration by the action GETACCESS. Successful registration means, that the script S1 doesn't modified values of these objects. It is a competitive access of two parallel running events to the same objects.

Related pages:

Script actions

 

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