PACSystems™ RX3i and RSTi-EP CPU Reference Manual Appendix A
GFK-2222AK October 2019
Serial I/O, SNP & RTU Protocols 199
The following diagram shows the differences between the full sweep phases and the base
sweep phases.
Base Sweep vs. Full Sweep Phases
<START OF SWEEP>
Sweep Housekeeping
NULL Input Scan
85
Program Logic Execution
NULL Output Scan
85
<END OF SWEEP>
<START OF SWEEP>
Sweep Housekeeping
Input Scan
85
EGD Consumption Scan
86
Program Logic Execution
Output Scan
85
EGD Production Scans
86
Poll for Missing I/O Modules
87
Controller Communications Window
Backplane Communications Window
<END OF SWEEP>
For the base sweep, if there is no configuration, the input and output scan phases of the
sweep are NULL (i.e., check for configuration and then end). The presence of a
If I/O is suspended, the input and output scans are skipped.
If no Ethernet Global Data (EGD) exchanges are configured, the consumption and production scans are skipped.
Polling for missing I/O modules only occurs if a Loss of ... fault has been logged for an I/O module.
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