I've been asked to network three existing Siemens S7-300 PLCs in order to collect and publish some data in a new Scada System (I've not decided yet which software to use)
Actually the three PLCs are stand-alone, each one connected with a Siemens OP7 Panel Operator:
1) CPU-314 -> OP7
2) CPU-314 -> OP7
3) CPU-313C -> OP7

At the moment I don't know exactly the distances between the PLCs and the future Scada Server, but I think they will be about 300-400m far from the PC.

There could be the possibility to expand the system in the future, adding 4-5 new Siemens PLCs. The network should be used for data collection only, but I think it should be better to use a bus which can also be used for Remote I/O.

I'm a novice in the Siemens world and I'm studying hard the manuals, brochures etc. At the moment I think that a Profibus Network should be the right choice for the required goal but I'd like to hear from the experts what is their opinion, and I have some doubts:

1) Do I need to program the CPUs in order to communicate with the Scada Server?
2) Do I need to program the Op7 Panels in order to let it continue to communicate with the PLC?

Thank you,
Luca

 

1- No you don't need to write program for scada communication.
2- No you don't need to write program for OP communication.

i suggest to buy profibus cards for remote IO and scada communication if you have chance. Good luck.

 

Hello Luca;

Profibus sounds good for your application, although Ethernet could also be applied. For Profibus, you will need to consider a few points:

1) between 200m and 400m of bus length, maximum speed for the network will be 500 kBaud.
2) the 313-C is a new model CPU; what about thre 314? there is a difference in processing power and supported number of connections you might have to look into. Older model CPUs cannot support more than 3 Master class-2 connections on Profibus, so if the OP7s are Profibus-connected you might lose the link unexpectadly.
3) you do not need to reprogrogram the CPUs (maybe change the Profibus address to ensure each address is unique on the bus)unless you need to add a Comm porcessor for Profibus; adding a CP342-5 will mean building a comm. exchange table.
4) if the OP7s are Profibus connected already, you will have to make sure the Profibus address of the CPU is adapted to the new Profibus address.

This should be enough considerations for starters.

Hope this helps,
Daniel Cartier

 

You could connect all PLC and SCADA to an ethernet network, but you will add ethernet communication card to your existing PLC or use another communication port of existing PLC to be converted to ethernet.

 

Hi,

You can connect all the PLC on MPI bus. No additional hardware is required for this. Only the care shall be taken that the node address of each partner (i.e. PLCs, OP and SCADA) shall be different. No additional programming is required except changing the MPI address of each node on the MPI bus.

Regards,
AAS


On May 17, 2005, Luca wrote:
> I've been asked to network three existing Siemens S7-300 PLCs in order to collect and publish some data in a new Scada System (I've not decided yet which software to use)
Actually the three PLCs are stand-alone, each one connected with a Siemens OP7 Panel Operator:
1) CPU-314 -> OP7
2) CPU-314 -> OP7
3) CPU-313C -> OP7
>
> At the moment I don't know exactly the distances between the PLCs and the future Scada Server, but I think they will be about 300-400m far from the PC.
>
> There could be the possibility to expand the system in the future, adding 4-5 new Siemens PLCs. The network should be used for data collection only, but I think it should be better to use a bus which can also be used for Remote I/O.
>
> I'm a novice in the Siemens world and I'm studying hard the manuals, brochures etc. At the moment I think that a Profibus Network should be the right choice for the required goal but I'd like to hear from the experts what is their opinion, and I have some doubts:
>
> 1) Do I need to program the CPUs in order to communicate with the Scada Server?
2) Do I need to program the Op7 Panels in order to let it continue to communicate with the PLC? <

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