siemens outputs

Hi guys I have 10 inputs but need to fire one output with any two or less on. i.e if three come on it turns output off?
without using lines and lines of AND or OR gates?

I'm not familiar with the blocks of siemens S7

thanks Jimmy

Hi people may help with homework if you show your ideas so far

Math

I'm throwing an idea out there. I don't know if it will work but you could try using math to solve this.

1.Converting each input bool value to an integer of 1.
2.Use an adding function like a+b+c+d+e+f+g+h=x.
3.Use a compare function like, if x <= 2 then output=HIGH.

I've included a little, big drawing. Maybe adding pulse contacts to the inputs so that the MOVE and ADDING rate is slower than the scans. Not to sure how the MOVE function will behave if it is continously enabled.

Maybe some more experienced people here have more insight as to how you can develope this ladder.

http://i63.tinypic.com/sos6mo.jpg

.

For speed, have a lookup table of 1024 boolean values (32 DWORDs), and use your ten inputs as the index.

My understanding is you need to use STL for indexed addressing.

You will have to figure out indirect addressing yourself, but if the 1024 boolean values are stored from %MD0, And your index at %MW100

Here's one implemenation which uses a counter to count the bits.

Easy.
Map in inputs to a dword, any dword.
Use FC99 to count the number of bits that are true.
If <3 then turn output on.

FC99 can be found in the Standard library > TI-S7 converting blocks > FC99 BITSUM


Harder.
Map inputs to a (d)word, any (d)word.
Reset counter to 0.
If bit (d)word.0 is true, add 1 to counter.
Use SLW/SLD to shift (d)word right.
Loop back to "If bit is true" 15/31 times.
Once loop is done, if counter < 3, set output.