Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 231)

Publication 1785-UM012D-EN-P - July 2005
Programming Considerations 13-13
Completed State
Program has completed execution
or has not yet started execution
Ready State
Program would be executing if it were of a higher priority;
all programs pass through this state; there can be
several programs in this state at any given time
Executing State
Program is executing; only
one program can be in this
state at one time
Waiting State
Program is ready for execution but is waiting
for some event to occur (such as an input to
transition or a timer to complete)
Completed State
Program has completed execution
or has not yet started execution
Has a new program
(e.g., an MCP, STI, PII)
with a higher priority
become ready?
Yes
No
Does the program fault?
Yes
No
Faulted State
A run-time error
has occurred within
the program
Does an appropriate fault routine
choose to clear the fault?
Yes
No
Program counter is
adjusted to point to
next instruction
All active user programs
are aborted and processor
enters faulted state
Does the program request Yes
No
a remote block transfer?
(STI and PII routines only)
Waiting State
Rescheduling Operation
Rescheduling Operation
Rescheduling Operation
While block-transfer to remote rack
occurs, a rescheduling operation is
performed and lower-priority programs
are executed (unless all other
executions are prohibited by a UID/UIE
zone around the block-transfer.