S7 Ethernet comms

[CliveBaker]

I have installed a new s7 project an need to communicate to the existing S7 on site usng ethernet. I do not want to download the hardware config for the original site plc, as it cannot be stopped.

My question is, can I set up a ethernet link just to write to the site plc without having to stop it.

Both PLC's are S7 3xx and are using CP 343 -1 Lean modules; they are not in the same project and the one I need to write to, talks to other PLC's in its project by Profibus.

cheers Clive

 

[Jeebs]

In NetPro:

PLC > Download to current project > Connections and Gateways.

Allows you to download new/changed connections without downloading the HWConfig, thus without stopping the PLC.

 

[JesperMP]

I think that if you add a fully specified connection in NetPro, then that will change the HW Config of all affected stations, and that will require a download of the HW Config.
If adding an un-specified connection, the same applies, but only for the CPU where the connection is configured.

edit: jeebs are you sure that it is not necessary to stop the stations in question when downloading from NetPro ?

There are two methods for accessing a partner CPU via a CP343-1.
S7 connections, and AG_SEND/AG_RECEIVE.

In theory, a solution to your problem of not being able to modify the partyne CPU, could be to create an un-specified S7 connection. That will only affect the CPU that initiates the communication via PUT or GET commands.
The bad news here is that CP343-1 LEAN only supports "server" functionality. That is a way of saying that the partner or both CPs have to be the non-lean version which can do both server and client.
And AG_SEND/AG_RECEIVE always require that there are connections setup in both stations.

Your best bet at the moment is to wait for a scheduled plant stop (for maintenance maybe), and then setup an AG_SEND/AG_RECEIVE connection.
edit: AG_SEND/AG_RECEIVE should be possible without downloading a new HW config.
You have to add code in both PLCs, but do not have to stop the CPU.

 

[Jeebs]

Nope, no need for full download, no need for stop if you create a new connection in NetPro.

Last time I did it we had to create connections in well over 20 PLC's crossing several projects, not one PLC needed to be stopped to download the connections.

Anyways, Clive can create the new connection in the new S7 install and test the download before doing the same on the existing system.

 

[JesperMP]

Thanks jeebs.
That is really useful information. Until now I have just downloaded the full station. I shall give it a try.

I have modified my previous post.

 

[KalleOlsen]

Nope, no need for full download, no need for stop if you create a new connection in NetPro.

Ditto experience here.

Kalle

 

[CliveBaker]

Thanks for all your comments but I cannont seem to add a connection.
I have added AG_SEND and set up a new connection in my nre project, and added AG_RECEIVE in the exsiting project. But I cannot see them in NETPRO.

 

[JesperMP]

Start by adding a connection in NetPro.
It must be a type TCP, ISn_TCP or UDP protocols, not S7 protocol.
Then use the connection ID to setup the AG_SEND and AG_RECV blocks.

Here is a FAQ to get started:
http://support.automation.siemens.com/WW/view/en/17853532

A short description on the protocol differences:
http://support.automation.siemens.com/WW/view/en/16767769

 

[CliveBaker]

That my problem the insert new connection is greyed out.

 

[JesperMP]

Select the CPU, not the CP, then chose insert new connection.

 

[CliveBaker]

Ok I will try that thank you

 

[CliveBaker]

I set up the connection for the mew project and downloaded it, however when I tried the exsiting project, it would not download the message was could not connect to partner. The help tells me it happens frequently. I mest have done somthing while messing with the offline version of the Hardware config.
I went back to the origianal copy of the exsiting project but still could not connect. The network is fine i can ping the PLC but connot get online via ethernet.

 

[JesperMP]

What does your PG/PC Interface setting say ? S7ONLINE=?

 

[CliveBaker]

TCP/IP "network card"

 

[CliveBaker]

sorry got it wrong it is S7online.
But I am away from it at the moment I cannot access the internet from the PLC.
I will check it in a few minutes.