Hello,

first question is, if the Smartline Module is a Module with DRIVE-CLiQ interface (only 5kW and 10kW Smartline Module do not have DRIVE-CLiQ interfaces, all others have one). 

If it is a Module without DRIVE-CLiQ interface, you don't need to connect it to the Control Unit anyway.

If it is a Module with DRIVE-CLiQ interface, you connect it just to one of your Control Units. And also in the project it is just configured once under one of your CUs. 

The only thing that needs to be handled on the drives from the other CU is that you need to connect the enabled signal from the Smart Line Module to those drives. It is parameter p864 on the drives. By that parameter the axes "know" whether the Smart Line Module is enabled or not, which is important for enabling the drives. You could handover this enable signal via Digital I/Os from one CU to the other or via telegram if you communicate to your devices via PLC. 

Hello,

attached please find the connection example from the manual. You just need to connect the READY signal output from the SLM to Digital inputs of both of your CUs. 

In p864 of the drives you use this digital input (e.g. CU:r722.0, when using interface X122.0).

Resetting signal can be given from a PLC output or CU output. 

...ahh and here the link to the manual...from chapter 4.9 you find the detailed description:

https://support.industry.siemens.com/cs/de/en/view/109740021

Hello,

it is not necessary to have two line contactors in this case. You should just combine the switching signal of both CUs. So you pass the switching signal from the second CU to the first CU. There you could create one logical AND / OR signal (with Free Function Blocks or DCC) and this signal switches the line contactor. You can pass the switching signal from one CU to the other one via Digital input / output or via field communication (if you have a PLC).