Profibus Encoder with drives.

I am thinking of using profibus to control 6 drives and an encoder.
Do you think there will be speed / comm's issues?
The encoder will be opening and closing timing windows for a press.
they are 20mSec wide.

Has anyone done this?

The safe bet would be to put in a card in the Siemens S7 for the encoder and not use P'bus but that seems a backward step.

I just got this yesterday from Siemens weekly email. Maybe it will be some help.

Technology CPUs: Feeder for a press based on static cam disks

http://support.automation.siemens.com/WW/view/en/21363677