Rockwell Automation Logix5000 Controllers Controller Information and Status Programming Manual - Manual (Page 48)

Chapter 4 Change detection
Attribute Name Description Access
ChangesToDetect Used to specify which changes are monitored. When a monitored change
occurs, the Audit Value is updated. GSV/SSV
ChangesToDetect
The ChangesToDetect mask is a 64-bit value. Each bit of the ChangesToDetect
mask corresponds to a particular event that could cause the Audit Value to change.
See ChangesToDetect Format on page 50 .
Important: Change detection is unavailable on the RSLogix Emulate 5000 Controller and the SoftLogix5860 Controller.
If a bit is set to a value of 1, the corresponding event is monitored for changes and
when a change for that event occurs the AuditValue updates. If a bit is set to a
value of 2, the corresponding event is not monitored and does not affect the Audit
Value. The default Audit Value of: 0xFFFFFFFFFFFFFFFF indicates that all
events are monitored.
Tip: The Audit Value updates when the controller is online.
Some events always update the audit value when they occur. For example, the
audit value changes when a project is downloaded to the controller, or when
ChangesToDetect is reconfigured. These types of events are not included in the
ChangesToDetect mask.
You can configure the ChangesToDetect mask programmatically using SSV, GSV
and MSG instructions.
Tip: You can use the Security tab in the Controller Properties dialog box to configure Change Detection if you are using
version 20 or later of the application. See Change detection in Logix Designer Application on page 51 .
Use the Set System Value (SSV) instruction to write to the ChangesTo Detect
attribute and the Get System Value (GSV) instruction to read the ChangesTo
Detect attribute programmatically.
48 Rockwell Automation Publication 1756-PM015F-EN-P – October 2014