Siemens S7-300

BNA · Nov 10, 2004

Hi' All

For a project i need to keep count of how many pieces the machine makes, is it in any way possible to store a value from a counter even if the Plc is powerless for 3 months or more, or do i have to purchase a mecanical counter for this ?

Regards

Brian

rgua · Nov 10, 2004

Data blocks, in new S7-300 CPUs, are stored in the flash card MMC. For ever.

BNA · Nov 10, 2004

I know how put put the counter value into a datablock but this will by set to initial value if you repower the Cpu.

How do you STORE the values in a datablock on the memorycard ?????

rgua · Nov 10, 2004

CPU 300-C
SIMATIC Manager / Station simatic 300 / Hardware / Open CPU --> Retentive memory and select "Number of S7 Counter Statrting with C0:

memory areas will be retentive even without a battery backup (in the backup memory of the CPU).

RMA · Nov 10, 2004

You don't need to, the current S7 300 CPUs do it for you, although be aware that in some of the CPUs (for example the 317) you can define some DBs to be non retentive. By default, DBs are always retentive (as are all other memory areas, Merker, Timer, Counter, etc., although you can usually define that only a certain part of the memory is retentive, or in the case of the smaller CPUs, this is predefined).

Edit: I see I overlapped with rgua, but in essence we're saying the same thing. The question is, do you really need to save your counter value in a DB, or will it suffice to make the counter itself retentive as described by rgua?

RRobbins · Nov 11, 2004

Just remember, the counters only go up to 9999. If you want to go higher and retain the count (counters are non-retentive) use a DINT (Double integer) in a DB. You can go up over 4 billion. Use the Integer function from the menu and you will see ADD_DI. If you want to be creative, you could create a DB, fill it with DINTs and store 4 billion counts for each day for a few years. It would only take a few lines of code.

RMA · Nov 12, 2004

The S7 Counters are (for a definable number) retentive in current 300-Series CPUs, but as RRobbins says, they only count to 9999.

The IEC- Counters count over the signed integer range of ~-32k - +32k, but are NOT retentive.

If you need large counts AND retentive, the DINT / DB solution is the way to go.

PLucas · Nov 12, 2004

RRobbins said:
Just remember, the counters only go up to 9999.

Shouldn't that be 999 for simatic counters and +32767 to -32768 for IEC counters.

Paul

RMA · Nov 12, 2004

Shouldn't that be 999

Oops, just copied that without thinking, maybe I need another coffee!

+32767 to -32768 for IEC counters

That was just me being lazy - I did say "over the signed integer range " and "approx." (~)!

PLucas · Nov 12, 2004

Roy,

I didn't notice that you had posted a minute before I did, so the IEC ranges were not aimed at your laziness

Paul

RMA · Nov 12, 2004

Paul,

hadn't noticed the times or I might have realised that!,

Cheers
Roy

About time I went and did some work, it can get addictive here!

BNA · Nov 12, 2004

Thanks

The solution whit the DINT is what i need, this machine is running aprox. 60 strokes/min for 8 to 10 hours a day, and the counts will only be reset ones or twice a year.

So i think that the retentive DB whit DINT is what i need.

SaenenDirk · Nov 19, 2004

better not to use a standaard s5-counter.

built your own counter with a DBx.DBDxx
(a double word in a datablock)

retentive, and counts up to 2.000.000.000.....

Siemens S7-300

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