Rockwell Automation 1747-PCIS API Software - Open Controller - Manual (Page 18)

Publication 1747-UM002A-US-P - June 2000
1-6 Overview
In addition to providing access to the control scanner, the dual port
memory also provides non-volatile (optional battery-backed) storage
for:
•
I/O values
•
application parameters (timers, counters, presets)
Scanner Modes In both application types, the scanner CPU operates in six
basic modes:
•
performing POST (power-on self test)
•
waiting for host initialization
•
Idle
•
Scan
•
Faulted
•
non-recoverable fault
After the scanner successfully completes the POST, the scanner waits
for an initialization complete command from the application. Once the
scanner receives this command, the scanner enters Idle mode.
Before the scanner can enter Scan mode, the application must
download a valid I/O configuration to the scanner.
If a recoverable fault occurs, the scanner enters Faulted mode. Use the
OC_ClearFault API function to clear the fault before the scanner can
resume operating in Scan mode.
If a non-recoverable fault occurs, reset the scanner (cycle power).
Some possible non-recoverable faults include:
•
POST failure
•
background diagnostic failure
•
internal watchdog timeout