S7 - Timer with variable times

[RMA]

One disadvantage I've realised (oh, great, says Roy, now he tell's me!) is that the two tables have to be of the same datatype. You may have to do a little additional conversion coding to get your times in a suitable fashion. Using a catch-all of WORD for both the energy and the timer duration may be the KISSest answer.

That's no problem in itself, I had to create a new DB pair for the Time duration anyway, since I've decided to go the Down-counter route, that was automatically in INT anyway. Since I'm displaying the Total Energy on the HMI, I had to cahnge it to INT as well for ProTool, so it was already available.

The main problems are that I'm not quite sure what you meant by having to declare the parameters as ANYs - which parameters, where?

The other major problem is the peculiar disappearing - and apparently resetting - Pointer entry.

 

[USDutchman]

Dumb thought?

RMA,

Just a thought,

I am using a function (FB) for a while now, that is doing pretty much what you want. Unfortunately, it is written in the spaghetti style you didn't want (If I have some time I may recode it using STL code and a loop someday). However, since it is inside an FB, who cares?? (Hint, you can always turn on Know how protect, and only explain the outer workings of the Function )

The little advantage I put in my FB is the following:

The DB associated with the FB is setting up a table (Array of input (real) and Output (real) size 24).

The routine scans through the input table, until it finds a value bigger then the input given. Then it uses an interpolation algortihm (using an FC) to find the output value.

Using this method it usually takes much less data points to describe the curve.

I laso have a stupid question: Where do you find the manuals of these library functions?

 

[Ken M]

Hi USDutchman

There are two volumes of pdf manuals I'm aware of that Siemens publish which cover all the standard library functions and function blocks. Try these links -

http://support.automation.siemens.com/WW/news/en/1214574

and

http://support.automation.siemens.com/WW/news/en/1214904

Roy,

I must get myself in front of a PC with STEP7 at some point and try this for myself.

Regards

Ken.

 

[RMA]

Hi Ken,

if you can, I'd be interested. I'm back home for the weekend, so can't try anything out till Monday. I'd like to get this working, because it's a reasonable compromise between something that you can see at a glance what's going on, even with 21 copies of the same program (since the program for each module fits on the screen), OK, it demands a good description in the comment field, but I can live with that.

USDutchman,

if we can't get this working, I'll come back on your offer. It's no problem if it's commented in Dutch, between German and Scots, I find I can read Dutch quite well although I can't cope with spoken Dutch (I did a couple of sewage treatment plants for a Dutch company), with Swedish it's the other way round, I can understand it when it's spoken, but I can't read it!

 

[USDutchman]

Dutch/English

This particular function is documented in English.

I wrote it years ago for a job in Italy.

Since I can only order food and drinks in Italian, everything was documented in English.

Attached some cutouts of the project documentation