Multiple Master profibus

[Gevorg]

Hi all.

I'm new in using Profibus.

So now I have the following situation.

I have an encoder which has a profibus interface, and a third party PLC which reads from the encoder by profibus.

I need to add a cRIO which will also read from the encoder by profibus using the C-series profibus module.

But I wonder if it is possible to have two profibus masters (the third-party PLC and the cRIO) and one profibus slave.

Can anyone clarify this point?

P.S. I don't know what is the exact type of profibus of the encoder (DPV0, DPV1 or DPV2), if it matters at all 🙂

Thanks a lot.

Gevorg

[fromm8]

Hello Gevorg

To help you with your question, you should post here in order to reach the engineer with more expertise on Profibus.

Regards

Frank R.

[Jesse_D]

Hi Gevorg, 

Sticking two profibus modules as masters on the same network will not work. However, if your slave supports DP1 we may be able to do asynchronous communication over an FNL switch. Can you check if your slave supports DP1 and post back? 

[Jesse_D]

Hi Gevorg, 

I pinged Comsoft on this question and they had the following input: 

"DPV1 will be an opportunity to read acyclic data. But not for cyclic data.

This means DPV1 normally will be used to configure a slave (as example to reset a weighing scale or change from kg to lb ).

DPV1 can’t be used to read the cyclic data (as example the weight value itself).

Profibus DP does not allow that a second master can read/write cyclic data.

To make the slave cyclic data available to the cRIO PB module there is a possibility that the master mirror the data to our cRIO PB slave module.

This means that the third party PLC ( DP master ) has to read/write data from the existing slave and then mirror the data to our cRIO PB slave module."

Let us know how things go or if there are questions.