Logical names

Control devices with identical logical names share security permissions across different control networks and across different computers, without requiring identical

RSLinx Classic

driver names or relying on identical network paths.

Logical Names are required to configure security for ControlLogix controllers.

Logical names can be used as aliases for control devices with multiple paths, so that each instance of the device is associated with a single set of security permissions.

After adding a logical name for a control device, the security system automatically uses the security permissions associated with that name, rather than with the device's network relative path, to determine access permissions.

After defining a new logical name, establish security permissions for the control device. Be sure to add an identical logical name for the control device on each computer on the network that has access to the device, if the different computers have different relative paths to the device.

If security is configured for a control device identified by a network relative path, and then later a logical name for the device is added, the original security permissions are not lost; they remain associated with the path, but they do not transfer to the logical name. As a result, the original security permissions are no longer accessible, because security now attempts to access the security permissions using the name, not the path.

If a control device's logical name is changed, the original security permissions remain associated with the first logical name. Re-add security permissions for the device, to associate them with the new logical name.

When a logical name is deleted, the security system automatically uses the security permissions associated with the device's network relative path.

The logical name and its associated security permissions still exist in the security system after a name is deleted. For example, suppose the name "MyPLC1" is assigned to Device1 on Computer A and Computer B, and each computer has a different relative path to Device1. When a user attempts to perform an action on Device1 from either computer, the security system checks the permissions associated with "MyPLC1."

Now suppose we delete the name "MyPLC1" on Computer A, but leave it assigned on Computer B. If a user attempts to perform an action on Device1 from Computer A, security uses the permissions associated with the Device1's network relative path. If a user attempts to perform an action on Device1 from Computer B, however, security uses the permissions associated with the logical name "MyPLC1."

Do not delete logical names for

RSLogix 5000

controllers. Because

RSLogix 5000

controllers do not have network relative paths, deleting a logical name can cause unexpected results.