Hello chayma;

Do you mean you want to connect the S7-1500 as a Profibus slave to a S7-400-5H Profibus master?

In that case, the S7-1500 must have a CM 1542-5 Profibus slave module installed and configured on its rack, which will give you a single connection point to Profibus DP.

And between the redundant S7-400-5H CPUs and the CM 1542-5, you will need also a Y-Link, an intermediate connection point that will allow a redundant msster system to conect to a non-redundant slave. See the picture attached below for an explanation.

Here is a detailed description of the construction of a Y-Link:

https://support.industry.siemens.com/cs/ca/en/view/43688632

The following manual has dedicated chapters for the setup and configuration of a Y-Link:

https://support.industry.siemens.com/cs/ca/en/view/109805389

In case you choose to use Profinet connections instead of Profibus, te setup is much easier, since you can use the integrated Profinet interfaces both in the S7-400-5H CPUs and on the S7-1500. But you must connect the partners in a MRP ring configuration, as explained in this document:

https://support.industry.siemens.com/cs/ca/en/view/66644434

Hope this helps,

Daniel Chartier