The behavior of the E-stop button on all cabs is based on which command station is being used.
The E-stop function of the Power Cab and SB5 systems is single loco only regardless of which cab triggers the E-stop. This is different from the multi stage / full layout shut down E-stop on the 5amp Ph-Pro / Power Pro system.
The "Big Red Button" on the Power Cab and Pro Cab throttles does a few different things:
Press this button once to stop the current locomotive selected on any NCE system but leave the speed setting intact.
On a PH Pro a second press will reset the loco to 0 speed.
A third press will shut the entire command station down. The full system wide Estop is only available in the PH Pro command stations.
The Estop in the Power Cab and SB5 is a single key press for the current locomotive only. While in Radio mode the red button also serves as a power button for the throttle.