Profibus DP between two S7-1200

[mikla90]

So it's either two masters with the DP/DP in the middle or master slave. But what do you mean with "i/o communication"? Don't both PLCs have the same addresses for i/o?

 

[sigmadelta]

I/O means exchanging data via I and Q addresses (Q to I and I to Q) You set this up in the CP1243-2.

 

[mikla90]

Oh, ok, I got to that point. So it wasn't my fault, it's just a wrong configuration. Thanks guys, I was getting mad!

 

[sigmadelta]

Just to clarify, you can use PUT/GET with two CP1243-5's (Profibus Master)

 

[mikla90]

Ok, I'll keep this in mind! Now, all I have to do is set up the addresses in the iSlave configuration and then I'm good to go! Right?

 

[sigmadelta]

Yes, just use the appropriate I and Q addresses in your programs. (Ix.x for bit, IBx for byte, IWx for word and IDx for double-word, same for Q)

 

[mikla90]

re Wonderful! Easier than I thought! Thanks!

Edit: One more thing. How do I use the new variables? I set them up in iSlave communication, but can't find them anywhere in the program. For example, I set up a variable called Bit1 at Q2 in the master. Now where can I find it and how do I implement it in the MainOB?

 

[sigmadelta]

You have to create the tags yourself with the appropriate I and Q addresses in the tag table.

 

[sigmadelta]

Use the tag on a bit instruction such as a NO contact or coil.

 

[mikla90]

You mean the tag table in device configuration? Or which one? And I have to link all the single adresses like I4.0 to Q4.0, 4.1 to 4.1 and so on?

 

[sigmadelta]

From the project tree, go to PLC Tags -> Default tag table

Yes all Q addresses from the master transfer to the I addresses in the slave automatically, same with the I addresses in the master from the Q addresses in the slave (Q4.0 master to I4.0 slave, I2.0 master from Q2.0 slave, for example).

You just reference the addresses, you don't have to transfer anything, it is automatic.

 

[mikla90]

Oh, ok, so if I lets say I do something on I4.0 in the slave, it will automatically reflect in the master on !4.0, am I correct? It's like the same variable with two names. Right?

 

[sigmadelta]

I4.0 in the slave reflects Q4.0 in the master, correct.

And yes it's like the same variable with two names, if you want to think of it that way. They don't have to be the same name, it's up to you.

 

[mikla90]

Ok, I got the point of the whole thing. It's much easier than I tought, at least on words. Just, can you explain to me what it means that they don't have to be the same name? I can name them differently as long as they have the correct adress? Is it really this "forgiving" the TIA Portal??

P.S. Sir, I'll never come to Canada probably, but if I ever will you have a truck of beers paid!

 

[sigmadelta]

They are 2 separate PLCs with separate tag tables, you have to create the input and output tags on each PLC separately... so they can have the same name or different name. As long as you line up your addresses properly with your code, you're ok.

I'm actually in Bulgaria (read my location a bit closer )