Thanks for ur reply Mr. Gopalkrishna
but the problem is...
there are totally four slave controllers and each time slice is 100 milli seconds .so to get its time each slave controller have to wait for 300 ms. the master must react immediately without any delay( < 10 ms) for any faulty conditions in slave controllers.

so i am planning to put an extra faulty control line between all controllers. so if this line set then the master can know that there is a fault and it will stop its function and come to default state .
Is this a good idea or not ?
or can we communicate otherway plz suggest

regards
srinu