Hello:
I found the solution in a Robot, unfortunately I had no choice to implement in my aplication as it was already delivered (finally I did with interruptions).
Something like this should be implemented in SPS routine.
In this case when PLC sets Input 180, robot sends feedback and cancels cell.
With input 181 from PLC, Cell is started again
IF $IN[180] THEN
PULSE($OUT[180],TRUE,0.4)
cwrite ($cmd,stat,mode,"cancel/R1/cell()")
ENDIF
IF $IN[181] THEN
PULSE($OUT[181],TRUE,0.4)
Cwrite ($cmd,stat,mode,"run/R1/cell()")
ENDIF