Instruction Timing; Overview - GE PACSystems RX7i Reference Manual

A-2 Instruction Timing
A-2.1

Overview

The tables in this section list the execution and incremental times in microseconds (µs) for each function
supported by the PACSystems CPUs. Two execution times are shown for each instruction.
Execution Time Description
Enabled Time in µs required to execute the function or function block when power flows
into the function with valid inputs.
Disabled Time in µs required to execute the function when it is not enabled.
Notes:
All times represent typical execution time. Times may vary with input and error conditions.
▪
Enabled time is for single length units of word-oriented memory.
▪
COMMREQ time was measured between CPU and Ethernet module with NOWAIT option.
▪
DOIO time was measured using a discrete output module.
▪
Timers are updated each time they are encountered in the logic by the amount of time consumed by
▪
the last sweep.
Performance times for the BUS_ functions were measured on the RX7i using a Series 90-70 Genius
▪
Bus Controller, and on the RX3i using an RMX128 Redundancy Memory Xchange Module.
Performance times for all redundancy (CRE and CRU) CPUs were measured with ECC enabled.
▪
Due to a change in caching, measured times for some instructions changed for release 6.0 as
▪
compared to releases 5.0/5.1. It was found that increases in some instructions were offset by
decreases in other instructions, so that no effective net change was observed.
GFK-2222AD April 2018
Appendix A. Performance Data
261