Siemens Ethernet Comms

I have been using Profibus but I may have an application where I have to use Ethernet. I have a couple of questions.

I dont know much about using ethernet in step 7 but I am guessing it will be close to profibus just using different read/write's. Is this a correct assumption?

I am using WinAC running on a box PC620. Can I use one of the ethernet ports on the computer or will I have to use an add on card? If I can use these ports how do I set them up in the hardware config?

Not an expert but an occassional user.

You don't configure ethernet connections in hardware config buit in net pro.

In net pro select the CPU and the networking set up appears on the bottom of the screen, there you can configure the interface.

Not sure what you'll need in the PC mind, probably Jesper or someone could fill you in on that.

Hi CharlesM

are you going to use Ethernet for i/o, or for HMIs or database connections, or.. ?
If it is the 1st, then it is actually very much like setting up Profibus i/o, and you do it in the HW Configuration.
If it is one of the latter, then there are several variants, most of them requires connections to be setup in NetPro.

You could try to describe the application a bit more.

I don't know much about it yet. All I really know is that it will be Modbus TCP. It is a process controller so I am thinking it will be more like I/O than a database. I have not worked with NetPro so I will study up on it. I also have a request into Siemens about the ports on the computer. Maybe they can be setup in NetPro but I have not been able to set them up in the HW-config.

I missed the bit about using WinAC. I dont know WinAC very much so I cannot really help.
It sounds like you should have the setup confirmed by Siemens before you decide which parts to purchase.

I know that there is a library for Modbus TCP comms with a Siemens Ethernet CP in a "normal" S7 CP. Maybe you can use this library. The library has to be purchased, and I dont know the price of it, if you get it I would like to know.

Possibly you could also go out via OPC.
Again it is a bit out of the ordinary, but with OPC DX you can connect "directly" to another OPC DX server. Notice, that OPC DX is not like the normal OPC DA.
Simatic Net supports OPC DX. Requires an additional license for DX.
You would need an OPC server for Modbus TCP that also supports OPC DX.
If you cannot find an OPC DX enabled server for Modbus TCP, then there is also the possibility to use an OPC DA Client for exchanging data between two OPC DA Servers.

Thanks I just wanted to know a place to start. Im sure I have questions and comments when I get started.

Fyi

Here is what I got from the Siemens form. It also has a link to an example project.

https://www.automation.siemens.com/ww/forum/en/guests/PostShow.aspx?PostID=32316

Here is a link to the Modbus TCP that I mentioned before:
http://www.industry.siemens.com/it4industry/EN/solution_services/SIMATIC_ADDONS/PROTO_MOD.HTM
It only mentions CP343-1 and CP443-1 for S7-300 and S7-400.
It is therefore not certain that it will work with WinAC and a regular Ethernet NIC. I would ask Siemens directly about it.

If it doesnt work, then the solution is to use OPC as mentioned before.

Either
Simatic Net OPC DA Server -- OPC DA data exchange Client -- 3rd party Modbus TCP OPC DA Server

or
Simatic Net OPC DX Server -- 3rd party Modbus TCP OPC DX Server

I do a lot of ethernet communications, and one tip I can give you is to try building your own functions instead of using the Siemens functions. It is amazingly simple, and all you need to do is use SFC58 and SFC59.

Is it realistically possible for someone to write his own Modbus TCP compatible communication block ?

I'm not sure about ModBus, but I'm guessing it would be possible.

My note was more intended for ethernet comms in general. For instance, if I wanted to send or receive a UDP message, it can be done very easily without the Siemens blocks.

As Siemens has made their own blocks then it should be possible. Only I think it will take a lot of effort for the average dude.

About the very easy ethernet comms, then that sounds interesting. Fancy writing a guide ?

For the average dude maybe, but the people on this site aren't average.

Anyway, let's say I want to UDP broadcast 100 bytes to a configurable destination. I would set up a connection in NetPro using, say, connection 5 and I would check "Adressvergabe am Baustein" (I guess Siemens didn't know whow to translate it).

I would then set the port and IP Address in the header of the transmission, and it would just work:

L #Port
T DB10.DBW20
L #IPAddress
T DB10.DBD22

CALL "SFC Write Data Record"
REQ :=M10.0
IOID :=B#16#F4
LADDR :=W#16#3FF0
RECNUM :=B#16#6
RECORD :=P#DB10.DBX20.0 BYTE 106
RET_VAL:=#ReturnValue
BUSY :=#M10.1

AN M10.1
R M10.0

You can see that the message could easily be built dynamically.

apologies if bumping a 5 year old thread breaks some etiquette, but this looks to good to go past.

I'm interested in making a UDP broadcast from an S7-315. The receiving end won't always be alive. How would this code handle that case ?

My (limited) experience with UDP is completely connectionless, just specify a port and shout out the data, if someone listens or not is their problem.


thanks in advance

effgee said:

apologies if bumping a 5 year old thread breaks some etiquette, but this looks to good to go past.

I'm interested in making a UDP broadcast from an S7-315. The receiving end won't always be alive. How would this code handle that case ?

My (limited) experience with UDP is completely connectionless, just specify a port and shout out the data, if someone listens or not is their problem.


thanks in advance

Click to expand...

With UDP multicast i do it as follow:
Last word in message is e.g. integer between -32???..+32???. Increment it for each sending. That is more helpful for VAT-table than one bit between true/false.
Control previous/current integers by timer. If previous and current integers are equals too long time, connection is not alive.