I don't know your machine PLC and MD configuration. But I think for measuring purpose you have 2 options--from MDA or AUOT using NC program or you can cut off from spindle enable using PLC signals 

NC program like this:

N5 S4000 M3

N10 G4 X10

N15 M5 // spindle stop 

Or in PLC you need find DB3x.DBX 2.1 , then set it to "0" during spindle running. spindle will be stopped fast. here X=the number of axis# of spindle in MD , such as Axis 5 is spindle , DB35.

( you need know PLC SIMATIC and have the accesses of PLC program)  

gtsolid

Hi Raman, consider a spindle with high inertia that rotates slowly and at a constant speed. I would like to stop it in the shorter period of time using MDA mode and record the behaviour of torque, current, etc..