How to connect plc with 2 slaves via PROFIBUS DP

Hello Boris;

You have 3 nodes in your network, 2 end-nodes (one at each end of the network) and one middle-node. It does not matter where you have the PLC in this situation, it can be an end-node or a middle-nide.

Profibus-DP uses a daisy-chain (line connection) as shown in the attachment below. Start with your connector (with one cable only) , run the cable to your middle-node with 2 cables(one entering, one leaving the connector) and finish on the other end-nide. Termination resistors should be ON for each end-node, and OFF for the middle node.

The screenshot was taken from the Profibus design manual, from profibus.com, as part of the Profibus installation guidelines collection:

https://www.profibus.com/download/profibus-installation-guidelines/

Hope this helps,

Daniel Chartier 

dchartier

Hello Boris;

You have 3 nodes in your network, 2 end-nodes (one at each end of the network) and one middle-node. It does not matter where you have the PLC in this situation, it can be an end-node or a middle-nide.

Profibus-DP uses a daisy-chain (line connection) as shown in the attachment below. Start with your connector (with one cable only) , run the cable to your middle-node with 2 cables(one entering, one leaving the connector) and finish on the other end-nide. Termination resistors should be ON for each end-node, and OFF for the middle node.

The screenshot was taken from the Profibus design manual, from profibus.com, as part of the Profibus installation guidelines collection:

https://www.profibus.com/download/profibus-installation-guidelines/

Hope this helps,

Daniel Chartier 

 Thank you Daniel for answer. I have only 3 nodes and 3 cables from it. I cannot change connection inside node. In this situation - what can i do? Maybe this scheme will work?

Hello Boris;

I have taken the liberty to modify the first drawing you proposed, to explain the easiest way to connect your 3 slaves in a standard daisy-chain, as per Profibus-DP norms.

It seems that it should be quite easy to simp^ly connect the cables from slave 1 and slave 2 to the Profibus connector on the master (assuming it is the middle-npe, as desctibed in your original drawing.

If this is not possible, then you need some kind of T-Junction that will permit the connection over short runs of cable (less than 10 m if possible) and at a maximum bus speed of 1,5 MB. Industrial connectors such as this one from Weidmuller are a bit expensive, but they eliminate a lot of network problems and failures, especially in industrial environments.Non-industrial connectors exist or can be implemented by amateurs, but there will be no guarantee of stable network connections.

https://catalog.weidmueller.com/procat/Product.jsp;jsessionid=D67508A6DCE2D413FC477AEE51FA686A?productId=(%5b8564340000%5d)&page=Product

We have used this particular T-distributor in many projects, with mostly good results.

Hope this helps,

Daniel Chartier