GE PACSystems RX7i Reference Manual

Also see for PACSystems RSTi-EP: User manual CPU Programmer's Reference Manual

Contents

GE PACSystems RX7i Reference Manual Manual pdf 168 page image

Chapter 4. CPU OperationGFK-2222AD April 2018 1574.8 Clocks and TimersClocks and timers provided by the CPU include an elapsed time clock, a time-of-day clock, and softwareand hardware watchdog timers.For information on timer functions and timed contacts provided by the CPU instruction set, refer toTimers in PACSystems RX7i, RX3i and RSTi-EP CPU Programmer’s Reference Manual, GFK-2950 Chapter4.4.8.1 Elapsed Time ClockThe elapsed time clock tracks the time elapsed since the CPU powered on. The clock is not retentiveacross a power failure; it restarts on each power-up. This seconds count rolls over (seconds count returnsto zero) approximately 100 years after the clock begins timing.Because the elapsed time clock provides the base for system software operations and timer functionblocks, it may not be reset from the user program or the programmer. However, the application programcan read the current value of the elapsed time clock by using Service Request #16 or Service Request#50, which provides higher resolution.