Publication 1769-RN008H-EN-E - September 2005
CompactLogix Controller Revision 13 13
CompactLogix 1769-L31, -L32E, -L35E Rev. 13.21
CompactLogix 1769-L31, -L32E, -L35E Rev. 13.19
CompactLogix 1769-L31, -L32E, -L35E Rev. 13.18
Table 7 Corrected Anomalies
Anomaly: Description: Issue with time reported by real time clock caused controller to transition
to safe state (i.e., clear memory). During normal operation, the CompactLogix controller runs a background diagnostic to verify that the real time clock is working properly. When this anomaly occurred, the diagnostic indicated that the time reported by the real time clock was not what the controller expected it to be. In this case, the controller firmware interpreted the wrong clock time as a potential issue. By design, the controller transitioned to a safe state, clearing its memory and indicating that a major fault had occurred. The transition to a safe state was done as a preventative mechanism.
IMPORTANT: This issue was NOT an issue with hardware or controller memory. Instead, this
issue existed in the firmware diagnostic routine. The firmware revision specified by this release
note corrects this anomaly.
Table 8 Corrected Anomalies
Anomaly: Description: The WallClockTime increased after power cycles.
When the CompactLogix controllers had power cycled, the controller wallclock time increased.
The WallClockTime changed to an invalid value after restoring from CompactFlash at power up.
If you use a CompactFlash card and have it set to “restore on power up,” you may have needed to
reset the wallclock time. If maintaining an accurate wallclock time was crucial to your application,
you either had to disable the “restore on power up” feature or use a combination of GSV and SSV
instructions to check the wallclock time and, if necessary, reset it to a more accurate time.
Publication 1769-RN008H-EN-E - September 2005
CompactLogix Controller Revision 13 17
Restrictions The restrictions are organized by the catalog number in which they exist.
CompactLogix 1769-L31, -L32C -L32E, -L35CR, -L35E
Table 11 Restrictions
Restriction: Description: Irregular power cycles can affect the wall clock time.
Irregular power cycles, such as brown outs, can affect the wall clock time. If you use the wall
clock time for critical system timing, routinely synchronize the wall clock time to a master system
clock using a GSV instruction. If you have a CompactFlash card set to “restore on power up,” you may need to reset the wallclock time.
If you use a CompactFlash card and have it set to “restore on power up,” you may need to reset
the wallclock time. If maintaining an accurate wallclock time is crucial to your application, either
disable the “restore on power up” feature or use a combination of GSV and SSV instructions to
check the wallclock time and, if necessary, reset it to a more accurate time.
