S7 300 XOR flip flop

Guys,

Apologies as i know has being discussed many times but i can't seem to find the solution.

I have an s7 200 project that uses 4 box function to create a flip flop function for 32 buttons on a touch panel. The trouble i am having is getting the same code to work in an s7-300/400 project. I have attached the the s7 200 project and the block is HMI_CONTROL.

Any help on this will be greatly appreciated as in the s7-300 project there will be many more flip flops to be used.

P.S. Novice on s7-300. Little or no experience with stl but extremely willing to learn.

Regards,
Barry.

I dont have microwin at hand right now, so cant check it. But does your program use xor (I assume yes from title)?

S7-300/400 XOR behaves very stupidly, it actually checks if uneven amount of conditions is true. If uneven then result of XOR is true. If even then result is false.

This is just guess on what could be the problem. I really hate siemens xor.

TurpoUrpo said:

S7-300/400 XOR behaves very stupidly...

Click to expand...

How should it behave then ?

Well, it can be just me (and few others who actually did point out it for me) that it should be exclusive or as its name suggest. As in

x true
x true
x false
x true

would be false, as there is more than one condition true.

TurpoUrpo said:

Well, it can be just me (and few others who actually did point out it for me) that it should be exclusive or as its name suggest. As in

x true
x true
x false
x true

would be false, as there is more than one condition true.

Click to expand...

really?

i think simatic do it well

You have xored two variables, I was talking about case when there is more than two variables.

Technically XOR with more than two inputs is not defined. But most solutions XOR two bits then XOR the result of that with a third bit and so on until all have been included. Another name for what has been created,a s pointed out, is a parity generator. This one give a true output if an odd number of inputs are on.

But the original poster is trying to create 32 flip flop functions, presumably using word operations. If the S7 has 32 bit word operators then one way would be like this. I don't know the S7 instruction set so I'll describe it like this:

'Flip Flop' = 'Flip Flop' XOR ((Current PB Input XOR Previous PB Input) AND Current PB Input)

Previous PB Input - Current PB Input

I think he means processing all 32 bits in parallel like I do

LD dwInputs
ANDN dwLastInputs
XOR dwOutputs
ST dwOutputs
LD dwInputs
ST dwLastInputs

barryoc said:

Guys,

Apologies as i know has being discussed many times but i can't seem to find the solution.

I have an s7 200 project that uses 4 box function to create a flip flop function for 32 buttons on a touch panel. The trouble i am having is getting the same code to work in an s7-300/400 project. I have attached the the s7 200 project and the block is HMI_CONTROL.

Any help on this will be greatly appreciated as in the s7-300 project there will be many more flip flops to be used.

P.S. Novice on s7-300. Little or no experience with stl but extremely willing to learn.

Regards,
Barry.

Click to expand...

What is there in the S7-200 program can be converted to S7-300/400 without any problem.
The only difference is:

300/400 doesn't use byte based XOR, it uses word or doubles.
This means you'll have to expand the current byte structure to words.

A quick scan of the 200 program told me you can do the same there. You might wanna change the 200 program to word based as well, just for the sake of consistency.

Attached is a screenie of the XOR's. The rest can be adjusted to the new format quite easily.

Jeebs,

Tried your code and it works perfect.

Thanks,
Barry.