You have read correctly.  What real-world problem are you trying to solve that makes you think you need pointers?

hewking103

hi All

Bit shocked but i am learning - is pointer data type not supported in 1200s PLCs?

Regards

The SCL instructions PEEK and POKE can in many situations be used where we would use pointers like the ANY pointer. Below code idea scans through DB1 (not optimized) that has only BOOL tags. The function returns a TRUE when all bits are FALSE.

Code has been simulated in Step7 V17.0.0.6 for CPU1212 FW:V4.5.

Many ways to solve the problem of detecting ≥ 1 bit is true within a contiguous set of bits (bools).

If the bits are configured as an array of bool in 16 bit or 32 bit lengths, you can pass the array into an FB where you can overlay (using AT overlay method) the bits to a 16-bit WORD or 32-bit DWORD.

Then it's easy to detect a single bit = 1 (TRUE).

https://support.industry.siemens.com/cs/document/57132240 

Let's assume there are 16 or 32 input bits mapped (overlayed) to tag named "ALARMS" as Word or DWord.

To detect whether any alarm bits are set:

// 32-bit
        ALARMS
LAD:  ---[<>]---
     16#0000_0000

// 16-bit
        ALARMS
LAD:  ---[<>]---
       16#0000

SCL:
// Bool output returned to caller
AtLeastOneAlarmSet := (ALARMS <> 16#0000_0000); //32-bit
AtLeastOneAlarmSet := (ALARMS <> 16#0000);      //16-bit

hewking103

0_Einstein

You have read correctly.  What real-world problem are you trying to solve that makes you think you need pointers?

hewking103

hi All

Bit shocked but i am learning - is pointer data type not supported in 1200s PLCs?

Regards

Ihave DB with only boolean values which are alarms. I would like to check if any alarm is active in the big list of alarms. Is there a way compare actual data blocks with  alarms which can be active or not active with the copy of the datablock where all boolean variables are OFF and to check if they match? If they do not match this would indicate that at least one value must be active...

Do you know how to compare 2 datablocks?