We have a few 3.3KV motor starter assemblies in electrical room. To communicate to the DCS, we add a Profibus-DP card in each starter, but I am really confused by the user manual of Profibus-DP connection. Shall I ground each cable between two starters at both ends or at one end as the general instrumentation cable practice? Thanks for any advice!

 

Hello;

Do not confuse grounding and termination. Adequate grounding should be provided at every Profibus-DP node; we prefer a common grounding bar in our plants; refer to chapter 4 of the profn2_e.pdf manual, available on Siemens support website:
http://support.automation.siemens.c...hangelang=true&aktprim=0&siteid=cseus&lang=en

Once grounding has been taken care of, at every node you connect the 2 Profibus lines and the shield (easy to do if you are using standard Profibus cable and Sub-D 9 pin connectors, of if your drives have a dedicated Profibus screw-connection). At each extremity of the bus you set the terminating resistors (available through a switch on the Profibus connectors).

Hope this helps,
Daniel Chartier