S7-400 Send DB to S7-300 DB

[John Parker]

I have an S7-400 CPU connected to an hmi to enter setpoints. I need to send the setpoints to an S7-300 that is networked with the S7-400 but not with the HMI. Is there any way to copy a DB value from one processor to a DB in another processor? The data I need to send is an Integer. Thanks in advance.

 

[JesperMP]

Hi John.

There are many possible ways to do it.
But you have to tell us a lot more, in particular exactly what PLC types they are, and how they are connected with each other.

edit: The same goes for the panel. What type and how is it connected to the PLC(s).

 

[John Parker]

The 400 is a 416-2DP connected to the 300 315-2DP through Profibus DP. The 416-2DP is connected to the HMI through ethernet. The 416-2DP is preogrammed in CFC, SFC, with some STL. The 315-2DP is programmed in all ladder, with some STL.
Thanks for the speedy response.

 

[JesperMP]

And how are the DP ports setup on the two CPUs ? Master and slave, Slave and Master, Master-Master, or ?

And what about the panel ?

 

[John Parker]

They are Master-Master. Not real sure how to find out on the HMI. It is connected through ethernet to OS Server A and OS Server B using a CP1613. Where did the beer bump icon come from?

 

[JesperMP]

I think you must investigate a little bit more about the HMI.
The "OS Server A" and "OS Server B" sounds interesting. Is this maybe a WinCC installation with redundant connections ? It gets complicated.

Also, I have to ask, is the 315-2DP a backup for the 416-2DP by means of software redundancy ?
If that is the case, then we are talking about a completely different solution.

The reason that I ask about all the connection details is that the most elegant and simple solution is to setup routing so that the HMI acccesses both PLCs, even if not connected directly to one of them.

 

[John Parker]

Yes the OS Server's are redundant connections. The 315-2DP's (there are 4 of them) are running independent operations for automated strapping machines. The 416-2DP is controlling the cold finishing end of a steel mill. I have some timers on the strapping machines that were frequently changed by maintenance mechanics on the old AB system. They have no clue on the siemens system what to do so I am trying to get all the settings they used to change on a maint. screen on the hmi.

 

[JesperMP]

OK, I am getting the picture now.
We still need to know how everything is interconnected.
Now we have both Ethernet and Profibus. How is that connected to the 416-2DP ?

I am somewhat vary of changing the communication setup of the 416-2DP, as it has redundant connections. Is that made by you, or someone else ?

Anyway, I can foresee 2 solutions.

Setup an integrated STEP7 project with all stations. The HMI's can then access all PLCs memory via routing. It is the easiest and most flexible.

Setup S7 connections between the 416-2DP and the 315-2DP's. The 416-2DP can then send the DB to the 315-2DP's by means of PUT.
​

The bad news is that in both cases, you have to download an updated HW Configuration to at least the 416-2DP, but maybe also some of the other stations.
And since there are redundant connections setup, I think that is only possible by the person that has setup the system to begin with.

 

[John Parker]

It was originally installed by Siemens Energy and Automation Steel Mill Division. It is a multiproject with all of the PLC's and HMI's in there. The reason I am trying to do it this way is I made the db on the s7-300 and set the S7_m_c on the variable that I need a tag for. Compiled the OS and the tag is there for it. When I make the I/O field, download to the OS Server, refresh the screen on the client, the I/O field is there and can be changed but it has a crosshatch overlay which made me think something is not right. Pulled up the online Db and no values were being written to it. So i thought passing values through the 400 would be easier because I haven't had any trouble doing anything between the 400 and the hmi.

 

[JesperMP]

That all sounds as WinCC or PCS7 programming, and I do not have any experience with either.

The method you describe does sound as routing.

But I am farly certain, that if there was originally no data exchange configured between the HMI's and the 315'2DPs, then you need a HW Config dowload to the 416-2DP. The reason is that its routing tables has to be updated when you add data exchange with the 315-2DPs, and the 416-2DP shall act as the stepping stone.

I think that you should contact the original programmers that setup the systems, and ask for assistance. There are too many non-trivial techniques in action here.
Or, you should have a training in setup of a PCS7 project.

 

[John Parker]

Thanks for the attempt. Short on training fund now but learning it the trial and error way has worked best for me so far. I have some digital i/o pass through just haven't figured out the db yet.