Data Access Control
In RSLogix 5000 software, version 18 and later, you can prevent programmatic modification of InOut parameters by designating them as constants. You can also configure the type of access you will allow external devices, such as an HMI, to have to your tag and parameter data. You can control access to tag data changes with the Logix Designer application by configuring FactoryTalk security.
Constant Values
InOut parameters may be designated as constant value tags to prevent their data from being modified by controller logic. If the logic of an Add-On Instruction contains a write operation to a constant value parameter, the Add-On Instruction will not verify in the Add-On Instruction definition context.
External Access
External Access defines the level of access that is allowed for external devices, such as an HMI, to see or modify tag values.
Constant Values
InOut parameters may be designated as constant value tags to prevent their data from being modified by controller logic. If the logic of an Add-On Instruction contains a write operation to a constant value parameter, the Add-On Instruction will not verify in the Add-On Instruction definition context.
External Access
External Access defines the level of access that is allowed for external devices, such as an HMI, to see or modify tag values.
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