Bradley Smoker PLC-5 user manual Rescheduling Operation, An MCP, STI, PII Does the program fault?

Programming Considerations 13-13

Rescheduling Operation

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

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)

Waiting State

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.

Rescheduling Operation

Executing State

Program is executing; only one program can be in this state at one time

Yes

Has a new program with a higher priority become ready?

(e.g., an MCP, STI, PII)

No

Does the program fault?

No

Does the program request a remote block transfer? (STI and PII routines only)

No

Completed State

Program has completed execution or has not yet started execution

Yes Rescheduling Operation

Yes	Faulted State
	A run-time error
	has occurred within
	the program

Program counter is adjusted to point to next instruction

Does an appropriate fault routine	Yes
choose to clear the fault?
No
All active user programs
are aborted and processor
enters faulted state

Publication 1785-UM012D-EN-P - July 2005