GE PACSystems RX7i Cpu Programmer's Reference Manual

Also see for PACSystems RSTi-EP: Reference manual User manual

Contents

GE PACSystems RX7i Cpu Programmer's Reference Manual Manual pdf 343 page image

Chapter 6. Service Request Function328 PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual GFK-2950C6.30 SVC_REQ 50: Read Elapsed Time ClockUse SVC_REQ 50 to read the system’s elapsed time clock. The elapsed time clock measures the timein seconds since the CPU was powered on. The parameter block has a length of four words used foroutput only.OutputAddress Seconds from power on (low order)Address+1 Seconds from power on (high order)Address+2 nanosecond ticks (low order)Address+3 nanosecond ticks (high order)The first two words are the elapsed time in seconds. The second two words are the number ofnanoseconds elapsed in the current second.The resolution of the CPU’s elapsed time clock is 100 μs. The overall accuracy of the elapsed timeclock is ±0.01%. The accuracy of an individual sample of the elapsed time clock is approximately105 μs.WarningThe SVC_REQ instruction is not protected againstoperating system and user interrupts. The timing andlength of these interrupts are unpredictable. The clocksample returned by SVC_REQ 50 can sometimes bemuch more than 105 μs old by the time execution isreturned to the LD logic.