FIFO in s7-1200

Hi, I would like to use a FIFO with 20 items max. On the HMI i would like to display the next 5 items in the FIFO. This was easy in s7-200 as once a data item was taken from the FIFO, all of the data was moved by 1 position. This meant it was easy to use  tags for QueuePosition1, QueuePosition2, QueuePosition3 etc as they are in a fixed position.

I've tried to use the LGF FIFO function but this uses a pointer which moves around. How can i display the next 5 items in this case?

Alternatively, has anybody got code for FIFO that works exactly the same as S7-200

Many thanks

Mark

 Hello markgregory,

Would it be helpfull code in s7-300 in STL using Pointers or in TIA portal for s7-1500?

That would mean that you would have to convert code using Pointers in STL with  POOKE and PEEK functions into code usable to the S7-1200

markgregory

Hi, I would like to use a FIFO with 20 items max. On the HMI i would like to display the next 5 items in the FIFO. This was easy in s7-200 as once a data item was taken from the FIFO, all of the data was moved by 1 position. This meant it was easy to use  tags for QueuePosition1, QueuePosition2, QueuePosition3 etc as they are in a fixed position.

I've tried to use the LGF FIFO function but this uses a pointer which moves around. How can i display the next 5 items in this case?

Alternatively, has anybody got code for FIFO that works exactly the same as S7-200

Many thanks

Mark

Best regards Soble

markgregory

I've tried to use the LGF FIFO function but this uses a pointer which moves around. How can i display the next 5 items in this case?

Calculate their indices and copy them out of the FIFO array to place of your choice. 

Hi, thanks for quick reply- I'm not very experienced at s71200 . How would you go about calculating the indices?

Thanks

markgregory

Hi, thanks for quick reply- I want to use it on S7-1200 in tia portal. I'm not very experienced at s71200 (s7200 seemed to be so much easier). Any code examples would be greatly appreciated. Thanks

 Hello markgregory,

Here - FIFO [store Data DB into Buffer DB] is an example suitable for s7300/400 and S7-1500.

Instead of blockmove you can use BLOCK_MOVE_VARIANT, and instead of POINTERS use PEEK and POOK functions. Should be more easier than this example.

Best Regards Soble