There is such a vast amount of information on this site that I have not and cannot consume it all. I may be posting an opinion of mine that has been covered before, if so the moderators are welcome to delete it. My experience has taught me to correctly identify the difference between a stop button and an E-Stop button. A stop button will allow a motor to wind down to stop. The speed it slows down with is determined by how it connected or what it is connected to. If using a PLC or a VFD you can program a speed that you want it to stop at. If the motor is connected to something directly thru an on off switch, it will wind down from the load it is connected to. The stop button that is going to a PLC or VFD is just that a stop button. An E-Stop (this is my opinion) should never under any circumstances be connected to a PLC or a VFD. If the contact in the PLC or VFD should stick, (I've witness this in an AB PLC) you can push all the E-Stops you want but the machine will NEVER stop. That is why you hard wire an E-Stop in the control circuit ( as in directly to the motor starter). Now there is going to be some concerns as to how quickly your equipment will stop, but the point is you want it to stop. Anyone who sees a fault in my logic, I would welcome your experience and advice. As I said, I have personally seen an AB PLC contact card stick closed and every E-Stop on the machine was pushed and the monitors overhead all said the E-Stop was initiated. Only when a non-fused disconnect ( which is not used for stopping but for locking out and isolation when working on the machine) did the machine come to a screeching halt.