Rockwell Automation T80016 Application Note Maintenance Override Programming - Manual (Page 7)

Trusted TM
AN-T80016 Maintenance Override Programming
Issue 1 June 08 AN-T80016 7
Logic Chart
This table presents the logic in a similar way to Cause and Effect charts. It is recommended to analyse
the logic requirements of a function block before programming, because the resulting program will be
more reliable and robust to unusual combinations of inputs and internal states. List all inputs, all
previous values of inputs
Blank boxes in the table indicate ‘don’t care’ for that input.
OR MC GOA MOE OS OA Timer Implications Action
F
Maintenance Override disable
Clear OS, zero/stop timer,clear
OA
F>T T T
Override requested and
enabled
Set OA, start timer
T>
T
F>T T T F T <30s
Override confirmed Clear OA, set OS, zero/stop timer
F
Override cancelled
Clear OS, clear OA,zero/stop
timer
T F T >30s Override timer ran out Clear OA, zero/stop timer
T F F T No group override available Clear OA, zero/stop timer
The trip logic may be treated separately.
DI RS OS
T T Reset trip when input clear Set DT
T T Reset trip when Override set Set DT
F F Input tripped and no override Clear DT