Ok. Found it in this thread on CNCzone....
DRO
reset to zero if the Estop or limit switch are hit
.
"Your Initialization C Program gives you much control over
how things are handled. You can set the Destinations to
zero, or the last commanded destination, or the current
encoder position (assuming you have encoders).
To set the to the last commanded Destination instead of zero
change:
EnableAxisDest(xx,0.0);
to
EnableAxisDest(xx,chxx->Dest);
(replace xx with the axis channel).
Note that after an EStop or other incident the last
commanded Destination may be invalid.
HTH
Regards"