221
6-1-1 CPU01-E, 03-E Cycle Time
PC
cycle
time
End of program?
YES
NO
YES
NO
Power application
Clears IR area and
resets all timers
Checks I/O Unit
connections
Resets watchdog
timer
Checks hardware and
Program Memory
Check OK?
Services Link Units
ALARM/ERROR
Sets error flags and turns
ON or flashes indicator
Resets watchdog timer and
program address counter
Executes program
Resets watchdog timer
Refreshes input bits
and output signals
ALARM
(Flashing)
ERROR
(Solid ON)
Services Peripheral devices
Initialization
on power-up
Overseeing
processes
Program
execution
I/O
refreshing
Link Unit
servicing
Peripheral
device
servicing
The first three operations immediately after power application are performed
only once each time the PC is turned on. The rest of the operations are per-
Cycle Time Section 6-1
To Next Page
Loading...
