Profibus DP between two S7-1200

[mikla90]

Hi everyone. So, as I told first time I got here I'm a newbie in PLC programming so please be patient.
Here's the thing. For testing a device we make, I have to connect two identical S7-1200 CPUs via Profibus DP. Now, setting up the project was easy, just add the devices, the communication modules master and slave and then link the slave to the master.
The problem is when I go in the MainOB of the master and create a GET instruction in the properties section I can select the master, but not the slave! Or at least not via Profibus, only Profinet. Before getting on with memory and all the rest, why can't I see the slave even if it's connected and has a adress?
Attached a pic of the GET properties section.

Thank you!

 

[spaderkung]

Can not see the pics.

 

[sigmadelta]

You do not use PUT/GET for Master/Slave communication. You use just use I/O to communicate.

 

[sigmadelta]

PS: Why not Profinet?

 

[sigmadelta]

This may help you too:

https://support.industry.siemens.co...-1243-5-operating-instructions?dti=0&lc=en-WW

 

[mikla90]

My boss wants this, no chance of changing. When you say "just use the i/o" what do you mean? The master can read directly the i/o of the slave in its main OB?

 

[sigmadelta]

Ah ha! Sorry, I was too quick to answer... S7 communication is possible (PUT/GET).

Is PLC_2 connected to the same Profibus network as PLC_1 in the Devices and Networks?

 

[sigmadelta]

Your boss likes to spend extra money and time! Well there might be a reason, such as the Profibus cable already existing, or replacing an S7-200 system, or something like that.

 

[sigmadelta]

You can set the S7-1200 slave to be a slave of the S7-1200 Master.

 

[mikla90]

Yes, both connected to the same subnetwork Profibus_1, with adresses 2 and 3. I even set up a couple of iSlave adresses to see if that changes something. But still nothing.

Edit: if you want some screenshot, just ask. It's easier if you ask what you want to see than me screeshotting every single thing...

 

[sigmadelta]

Try right-clicking on each PLC -> Compile - Hardware (rebuild all) and then Software (rebuild all blocks)

 

[mikla90]

Ok, when I try to compile the hardware I get an error on PLC1. Translated in english is something like "link partially specified. Partner interface missing."
Clealry, I missed a spot. So, this is what I did.

Create a new project, adding both PLCs and both interfaces, linking the slave to the master, checking network parameters (speed and so on), added a GET instruction in the master and got the error above. Then, when I try to compile I get that error. What did I do wrong?

 

[sigmadelta]

Do both plcs have CP1243-5s? I did the same thing and have no errors.

 

[mikla90]

No, one has a slave unit, the 1242-5.

 

[sigmadelta]

Then you have to use I/O communication and not put/get