66 Rockwell Automation Publication 1756-RM012B-EN-P - April 2018
Chapter 7 Monitor Status and Handle Faults
Get System Value (GSV) and Set System Value (SSV) Instructions
The GSV and SSV instructions let you get (GSV) and set (SSV) controller
system data that is stored in device objects. When you enter a GSV/SSV
instruction, the programming software displays the valid object classes, object
names, and attribute names for each instruction. Restrictions exist for using the
GSV and SSV instructions with safety components.
For more information on which safety attributes are accessible via GSV and
SSV instructions, see the user manual for your controller:
• ControlLogix 5580 and GuardLogix 5580 Controllers User Manual,
publication 1756-UM543
• CompactLogix 5380 and Compact GuardLogix 5380 User Manual,
publication 5069-UM001
For general information on using GSV and SSV instructions, see the
Logix5000 Controllers General Instructions Reference Manual, publication
1756-RM003
.
Safety Faults
Faults in the GuardLogix 5580 and Compact GuardLogix 5380 system can be:
• Recoverable controller faults
• Nonrecoverable controller faults
• Nonrecoverable safety faults in the safety application
• Recoverable safety faults in the safety application
Nonrecoverable Controller Faults
These faults occur when the internal diagnostics of the controller discovers a
fault. If a nonrecoverable controller fault occurs, standard and safety task
execution stops and outgoing connections stop. Safety I/O devices respond to
the loss of output data by transitioning to the safe state. Recovery requires that
you download the application program again.
Nonrecoverable Safety Faults in the Safety Application
If a nonrecoverable safety fault occurs in the safety application, safety logic and
the safety protocol are terminated. Safety task watchdog and control
partnership faults fall into this category.
IMPORTANT The safety task cannot perform GSV or SSV operations on standard
attributes.
The attributes of safety objects that the standard task can write are only for
diagnostic purposes. They do not affect safety task execution.
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