Profibus To Modbus RTU

Hi,

I need to retrieve data from instruments running Profibus protocol to a PLC with Modbus RTU. How can I achieve the above? Pls advice. Thanks in advance.

Hello trader;

You don't mention the brands of PLCs you are using, so here are a few general ideas that you could look into:

-use a protocol converter (Modbus RTU master top Profibus-DP slaves). Google on protocol converters, there are many very reputable companies that produce excellent (if expensive) equipment.
-setup a Modbus RTU slave on the PLC that is the Profibus-DP master; connect it to the CPU that acts as Modbus Master, use it to transfer the data from the Profibus instuments.
-use an OPC server on a PC that is connected to both CPUs, transfer the data through OPC clients.
-Use a SCADA/HMI panel connected to both CPUs, write the Profibus instrument data to the database, read it from the Modbus CPU.
More ideas are probably available (I hope others contribute); if you give us more details on the setup, help should be also more precise.

Hope this helps,
Daniel Chartier

As well as Googling for protocol converters you can try the Profibus Organisation web-site http://www.profibus.org Once there, try searching for 'Modbus' (I know, I know, it sounds ridiculous!) in the Profibus section. You should get a more focused list of parts from various manufacturers, and some of them may even be Profibus certified slaves. I haven't looked at them in detail so I don't know whether they support all the features you need.

Regards

Ken

The simplest solution would be to install a Profibus Master module in the PLC and forget about RTU. If the model of PLC you are using does not support Profibus, consider converting to one that does.

How many "instruments running Profibus protocol" are involved here? How rapidly does the PLC need to get updated data from those instruments?

Hi,

Thanks guys for your replies. I took them into consideration. Found out that there is an Omron CS1D PLC sitting at site collecting data from the instruments. I am gonna use an Omron SCU(Modbus) to grad the data. Considering the Profibus to Modbus convertor is more expensive than the SCU.