◄Back

# Long description

(a) Controls in series. A flow chart shows the information through three boxes, one after the other. Each box can return and output fail or no fail. If the output of each controller, into the next then out of the final one is fail, then the system indicates an incident.

If any of the controller indicates no-fail there is no incident

(b) Controls in parallel. Information splits into three parallel paths, into three controllers – if any one of them fails indicates fail, the system indicates an incident.