Pick a string from the global constants

ing.lukic

Hi!

I have S7-1200. I defined global constants Text_1 = 'fhhfjfhfa', Text_2 = 'gfhjj', Text_3 = 'gfuag'...

Now, I have to assign a value to some string parameter equal to some of those constants. Which of those constants depends of integer number "i".

Is there easier method of this:

CASE #i OF

1:

#Text := "Text_1";

2:

#Text := "Text_2";

3:

#Text := "Text_3";

...

END_CASE;

I can't define  texts like retentive strings in DB, becouse I have 1000 texts and there is not enough retentiv memory in PLC. Problem will be easy if I can define constants like array, but it is not possible...

Is there any idea?

Hello.

What you ask is possible (constant text per DB).

Open a DB. Declare an array of strings. Then populate the "start value" with what you want those to be.

Make sure you do not write to it. You do not even have to make the DB to retain. Each time the PLC restarts, the "start value" will be loaded.

If you do want to write to it for making changes, then have the elements "retain". Then after power outage the changed value will be there.

~

How about adding THIS attribute:

The other option:

But then you have to use:

Thank you for your advices,

But now I have a problem with work memory. With 1000 strings in DB it is 260% full. If I store it in load memory, I need to copy DB to the work memory if I mean to reach out some of this strings... 

ing.lukic

Thank you for your advices,

But now I have a problem with work memory. With 1000 strings in DB it is 260% full. If I store it in load memory, I need to copy DB to the work memory if I mean to reach out some of this strings... 

 -1-

-2-

Notice that   -2-    has a 10 character limit set.

ing.lukic

Thank you!

That was very helpful, but I need to cut off some texts. With strings long 60 characters I have 70% busy of working memory.

Is there some idea to solve the problem with solution with constants?

The S7-1200 does not like processing ASCII text. 60 characters x 1000 is very big amount of data. There might be other ideas. One would involve using an MMC card and using recipe control.

What do you need the string for? If it is something that needs to be displayed on a (Siemens) HMI, other solutions may be available.

#dP

What do you need the string for? If it is something that needs to be displayed on a (Siemens) HMI, other solutions may be available.

I need that for sending SMS. There will be predefined texts which will be sent to mobile phone(s). Which text - that will be sent from a WinCC Prof.

In fact - that will be alarms from the sistem which contains 60 PLC's. All alarms are olready collected in the WinCC. Each PLC sends alarms by 3-4 DW tags. Several alarms can occured in the same time. I am planing VB script to send ID number of the alarm text, based on tags analising. One PLC will take this number and place it in a FIFO memory (maybe no longer then 10 registers). On the other hand, PLC will be taking numbers from the FIFO and will be sending SMS to the phones. I was planing to avoid sending texts from the WinCC to the PLC. Money is limited and I was planing to by only CP 1242-7 V2.