Yes it is possible to stop a motor by sending a 0 speed setpoint, but it is not reccomended that you do that. Always isssue a real STOP command (because the 0 speed point can drift around). You can still use ramp functions, one to ramp up to set speed, and another to ramp down to 0 speed, where your PLC program then disables the RUN command (same as STOP on most VFDs).
A quick way to set a straight-line start ramp is to set the acceleration time in the VFD. For example, if you want your motor to start at 0 and ramp to full speed in 10 seconds, then set the Acceleration Time parameter to 10 seconds. There is a similar setting for Deceleration Time.
If your Start and Stop ramps are not linear, then you probably would need to set up a ramping routine in your PLC program (although many VFDS now have built-in non-linear ramp functions).