even mach is step/dir that mean no real feedback position need from servopack
but all industrial machines  ,always show the real position ,and also check the following status
for example if driver in alarm and some one move by hand...etc..
is some one try implement that in mach?
 

I run analog servos with real position feedback with a Galil and Mach 4.

It all depends of where the control loop is closed.  Hint: It is NEVER closed on the PC with Mach.  In my case, the Galil is where the loop is closed.  Servo drives that take step/dir input close the loop in the drive itself.  If the loop is closed in the drive or the controller, it NEVER needs to be closed on the PC. 

The loop is closed on the PC for systems like Linux CNC because Linux CNC is running the real-time processes and the hardware motion boards are pretty much passive I/O devices.

So if you want industrial style feedback with motor position error monitoring with runaway alarms, get an industrial controller. 

We also have auxiliary position feedback where the DROs will display the feedback from an encoder but the planner runs the motors with step/dir.  But that is far beyond the hobby realm that is discussed on this forum.   We are taking Mach 4 Industrial level of support to get that going. 

Steve