Profibus Question

Hi there,

Could someone give me some advice on this one:

I am doing an upgrade to an existing S7-PLC system. The PLC is a S7-315 2 DP with 2 ET200m profibus remote stations.

I need to add 2 new remote stations, one is 50m from PLC and another is 600m from PLC.

The guys were going to bury the profibus cable in pipe to the 600m remote station on Monday.

The network speed is currently at 1.5MBbps and I don't want to reduce it dramatically.

What would you do? Install a repeater? Media converters?

The max distance for 1.5MB/sec = 200m.

Your looking to add 650m at least, but how long is your existing network?

You would need a repeater every 200m at most, but you must take into account what your existing network is.

I would consider fibre for the 600m run.

I would use fiber for the longer run. You can find information here: https://mall.automation.siemens.com...-1352-1-1961-1962-1975-1997-2001-&jumpto=2001

It is possible to push a 12 mbit/s connection up to 15 km with the right equipment.

If you can accept a drop in performance (*) to the new station 600 m away, then you could also consider to install an additional CP342-5 in the S7 PLC rack. Then use 187.5k for this new Profibus network via the CP. That can expand the reach to 1000 m.
*: Since it has its very own Profibus network, then it may be that the performance is quite alright.

Notice: With such long distances, it becomes critical that there is a good common ground that can counter voltage potential differences between the locations. If you use fiber, then you dont have this problem.

Thanks for the response guys. The existing network is no longer than 50m.

I am going to opt for some copper to fibre convertors. Has anyone used them before? Perhaps you can recommend a particular type?

Also the existing HMI is connected via the MPI port of 315-2DP. A new SCADA application is to be installed which will need to be communicating over Ethernet. Is there such a CPU that has 1 x MPI port, 1 x DP and onboard Ethernet? I know the 2DP/PN has Ethernet but has only one MPI/DP port. I have no space left on CPU rack to install an additional CP.

There are 3rd party suppliers of ethernet-to-MPI/DP adapters. Look for Deltalogic, IBH softec, and MHJ.
Apart from that, you could exchange both CPU and panel to get to a full ethernet and DP setup. Maybe your panel already has ethernet ?

That is basically what an OLM does.

Name brand Siemens, off brand would be Hirschmann. Hirschmann actually used to make them for Siemens, I don't know if they still do or not.