I posted a very comprehensive solution to this issue here: How to reduce deceleration time of spindle - #36 by tjp52 that details how to fix this. When “Custom ModBus VFD” is selected from the tool menu, which is configured as described in the above referenced post and the spindle is spun up to 20,000rpm then stopped, it takes only 5.75 seconds to come to a complete stop.
I don’t know how to explain the configuration of the pre-configured tool profiles since I can’t see or change those parameters, but in the “Custom ModBus VFD” profile, those parameters are exposed and can be customized as needed. I know that the “stop-write” parameter needs to be changed from 5 to 6 as shown in the above referenced post.
It just works if it’s configured correctly. Also it has been confirmed to work by a couple other fellow “OneFinity” users as shown elsewhere in that thread.