Profinet - layout & structure

Hi guys,
We have been disscussing with one of our machine suppliers about a new production line. The line would consist of different machine parts (marked 1,2,etc, in picture) and a central line controller (S7-400). My first idea was to use Profibus for all communcation between the line controller and the different machineparts. In that case, there would have been one CP 342-5 at each machinepart to make a separate Profibus network for internal coms. and a integrated DP-port for external coms. with the line controller.

Now, (as illustrated in the picture) the supplier has come up with the proposition of using Profinet for communication between the line controller and the machineparts (external coms.) and there will still be a separate Profibus network in each machinepart (internal coms.).



The supplier thinks that if each S7-300 would be equiped with PN/DP CPU:s (both PN and DP integrated) there would be no need of using CP:s.

As I see this, without beeing an expert on Profinet, there would be no possibility to use Profinet I/O coms. between line controller and machineparts (that would require CP 343 lean, right?). Instead you would have to use Profinet CBA?

Does anyone of you have any (positive) experience of the CBA?

As we do not have any other machine at our plant that is using Profinet, I don´t think that this project would be the best way of introduction.

This thread is an introduction for discussions and I will proceed with more info later. In meantime you are more than welcome to come up with further questions, ideas, own experiences, etc,,

Best regards
Wille

We use a similar hardware layout in some of our plants, however we don't use Profinet. You can use the normal in-built Ethernet communications (GET and PUT I think, just have to check this) to move the data around.

We are looking at the possibility of using Profinet for our new plant items, since our preferred drive manufacturer (SEW) has a Profinet interface card. It is early stages just now, but we will probably be adding Profinet to our list of allowed equipment in our standard specifications. We have already had a requirement for all new Ethernet equipment to be Profinet capable for a few years.

I have used Profinet once during a Siemens training session, and it doesn't appear any more difficult to setup or use than Profibus.

I've done it on a half a dozen projects. Largest one had 9 CPU's (8-315-2PN/DP & 1-317-2PN/DP). Each CPU receives about bytes of data from 317 and brings back bytes of status.


A few things to note about CBA (IMAP):
- each CPU can pass about 2800 of data TOTAL
- using array function you can pass about bytes in one continuous pass (connector).
- it's fast and very stable
- you can assign replacement values if connection broken (very handy)
- It requires zero code
- device status byte is built in by system (running, connected, etc)
- you will need IMAP

Note you don't have to use CBA/IMAP. You can use the CPU's as expected and just to SEND/RECV. I also like keeping each CPU's I/O and devices on Profibus. I wouldn't bother with CP-342-5 unless I had a lot of devices (more than 80). If you want to separate each side do it via repeater.

Nick
Here is a screenshot of a 315-2PN/DP properties in IMAP...

What does this IMAP stuff cost ?

One advantage of the suppliers suggestion is that the onboard PN port is much faster than the CP343-1.

JesperMP said:

What does this IMAP stuff cost ?

One advantage of the suppliers suggestion is that the onboard PN port is much faster than the CP343-1.

Click to expand...

When looking at Siemens A&D-Mall, the price for the software (6ES7820-0CC04-0YA5) seems to be around 2000 euro which sounds a bit expensive for a software that should be (in my point of view) an add-on to Step 7.

The speed is definitely an advantage with this solution and also the economic savings of not buying the CP:s.

Don’t use the CP card in the S7-300 series

The solution is OK and it looks like the setup for a project I am working on at the moment. (1 S7-400 master and 8 S7-300 PN/DP “slaves”)

Don’t use the CP card in the S7-300 series, because you will get trouble if you exchange large amount of data, due to the slow communication speed on the backplane on the S7-300. So use of the PN/DP CPU is the correct solution with use off the S7-300 series.

We have made some plants with use of Profinet, and have only good experience with Profinet.
You will have a very good data flow to / from SCADA, and data logging is working without trouble, also if you have a lot of logging tags.

So go for the Profinet solution.

I am having a little bit of trouble to see the clear difference between the "old" IE communications and Profinet. According to my knowledge, the Profinet comes in 2 shapes:

1. Profinet CBA - configured in IMAP software.

2. Profinet I/O - configured in HW-config and uses standard siemens blocks for putting data in interface db. This concept could be considered as a follower of Profibus DP, but not possible to use a PN/DP CPU directly as a I/O-device (slave).

If you use a standard TCP/IP connection through the integrated PN- interface would this be considered as Profinet or IE?

Maybe this is non-important details about the definitions?

/Wille

2000 Euro ! Yes that is expensive. Then again, it is just the same as only one of the 315-2PNDP CPUs (or 315-2DP + CP343-1 for that matter).
And it is a onetime expense.

The alternative is to exchange data by PUT/GET or similar.
What I have heard is the PN IO is much faster than any other type of ethernet communication (*).

*: At least with Siemens.