Hello  everybody!

In recentlly i have a problem about AR2 register

ok!  for example : code as follow:

this is a FB block

/// parameter

INPUT

InEnable BOOL;

InPA6  UDT90;

*******

OUTPUT

OnDone BOOL;

OnBusy BOOL;

******

/// STL code

NETWORK1

TAR1  pAddrReg1   // save AR1

TAR2  pAddrReg2   //  save AR2

NETWORK2

A                InEnable   /// here if "InEnable" is "1"

=                OnDone    ///  then here output is TRUE,result has been correct

*************

NETWORK3

L                 P ## InPA6

LAR2

A                 InEnable     ///  Notice :  problem has occured.   In here. "InEnable" is "0"

                                      /// i don`t know why? will be that result.......

=                 OnBusy      // LRO = "0"

/////////////////////////////////////////////////////////

thanks for everybody to view it

Hi miy_si

you should use AR2 with caution, because the OS use AR2 on occasion. AR2 is used for the DB offset in multiple instances and you have to use AR2 when programming multiple instance capable blocks. You also have to be careful when using complex data type as AR2 might be changed. All that being said I would suggest that in your case the problem is that you are pointing AR2 at a pointer (UDT90) not the value of InPA6. I would suggest to write InPA6 to a static area and then point AR2 (or if possible AR1) at the new value and then scan. Why do you not use PLCSIM to test your code?

Hi miy,

do you have TIA or Step7 classic?

bit7

Hi miy_si

you should use AR2 with caution, because the OS use AR2 on occasion. AR2 is used for the DB offset in multiple instances and you have to use AR2 when programming multiple instance capable blocks. You also have to be careful when using complex data type as AR2 might be changed. All that being said I would suggest that in your case the problem is that you are pointing AR2 at a pointer (UDT90) not the value of InPA6. I would suggest to write InPA6 to a static area and then point AR2 (or if possible AR1) at the new value and then scan. Why do you not use PLCSIM to test your code?

 Thank you for reply me!

before I have to test in the PLCSIM.  test result are the same with S7-300 PLC

thanks for everybody again!