Hi,
you say that you don't have an Estop? That's pretty bold, its about the ONLY input that has to be there.
Have you assigned a pin for an Estop? If you have then may I suggest terminating it with a low value resistor,
say 400 ohms, to either earth or logic high so that the Estop is not active. My thinking goes that if a pin is unconnected
noise impulses may cause the signal to go active.
Craig