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.
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.
When the controller is configured for Logix SIS, the SafetySILConfiguration attribute always shows a SIL 3 value even if your system functions at a SIL 2 level.
To obtain the status of your system, use a Get System Value (GSV) instruction in your program and plan for the tags you are writing the values to.
In this example, the GSV instruction is used to obtain the chassis ID of the chassis that is functioning as the primary. The PhysicalChassisID value is stored in the PRIM_Chassis_ID_Now tag. The PhysicalChassisID value that is retrieved matches the Chassis ID indicated in the Controller Properties dialog box.
Physical Chassis ID | Chassis ID |
|---|---|
0 | Unknown |
1 | Chassis A |
2 | Chassis B |
GSV Instruction to Get Chassis ID
For more information about GSV and SSV instructions, see the Logix 5000 Controllers General Instructions Reference Manual, publication 1756-RM003.
For more information about the REDUNDANCY object attributes, see Redundancy Object Attributes.
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