Couple things... First, it seems odd that you apparently don't have a spindle speed controller in your diagram. Are you really just going direct from the relay to the spindle motor? It is odd in another way too... You couldn't even jog your axis without the spindle being running which introduces all sorts of safety considerations. Therefore, my strong suspicion is that you are showing the relay to the drive. If that is the case, you might want to look at the drive more carefully. I'm not really sure exactly where that relay would be in the power chain, but you never want to put a relay between the controller and a spindle motor. VFDs do not like having heaters or relays after the drive. Your schematic implies that isn't the case, but given that the controller isn't even shown I thought it prudent to comment anyhow.

In addition to that, I'd look at the spindle controller (if any) and the servo amps a little more carefully too. Your estop paradigm is to kill power to the units. This isn't how the earlier Meldas equipment work. In this case, I'm talking about the M3xx generation because that is all I'm familiar with, but I suspect the later stuff is the same. In those cases, the drives have power applied to them all the time but the the bridge that powers the DC bus has a relay in the circuit. That relay is energized only when the control provides the correct signals *and* when the estop terminals are bridged. I suspect that your later generation MR drive is probably the same.