In the DeltaV system, locks prevent users from changing the parameters and parameter fields assigned to the lock and prevent users from performing certain functions.
Locks for parameters are assigned to parameter names rather than to specific instances of parameters. In other words, a lock on HI_LIM applies to all instances of parameters named HI_LIM. To lock a specific instance of a parameter, you must create a unique name for that parameter, such as HI_LIM1.
Locks and keys assigned at the field level override those on the parameter itself. This means that specific parameter fields can be open to a large number of users while the parameter as a whole remains generally restricted.
Because security settings on fields have precedence over parameter security settings, you must be very careful when defining access to fields. For example, if access to GAIN is restricted, but access to the CV field has been defined as less restricted, users with the less restrictive access will be able to change the GAIN parameter.
When users make write requests to a specific parameter field, the system checks for a lock on the field. If there is no lock, the system checks for a lock on the parameter itself. When there is no lock on the parameter, the default lock is used. Users can write to the field of the parameter only when they have a key corresponding to the lock. Additionally, the workstation properties can restrict parameter writes by area. That is, the parameter can only be written to if the user has the key for the area and that area is assigned to the current workstation.
Locks are also assigned to various user functions such as downloading, uploading, changing the configuration database and so on. Functions are assigned to default locks initially. You can change the lock associated with a function.
Security is located under the setup component in the Explorer hierarchy. Assign locks to parameters and parameter fields through the Parameter Security Properties dialog and Field Security Properties dialog under the Security section. Assign locks to functions through the Function Security Properties dialog under the Security section. You can also assign a default lock (keep in mind that many users might have a key to this lock). When you do not assign a lock to a parameter or field, the default lock applies.
If you want to remove all security from a parameter, the lock specified for that parameter must be assigned to all users. For example:
Rename an unused lock (for example, User Lock 10) to something descriptive like, "Everyone".
Use the "Everyone" lock on parameters that to which everyone needs write access (or at least to fields that do not have a field name lock defined).
In DeltaV User manager, create a group named "All Users".
Assign the "Everyone" key to the "All Users" group, sitewide (that is, in all plant areas defined).
Make sure all DeltaV users are members of the "All Users" group.
The result is that all DeltaV users get the "Everyone" key in all defined plant areas. This enables them to write to parameters associated with the Everyone key unless a field name lock exists.
If you create a new parameter in Control Studio with a unique name, you must add the parameter to the Parameter Security section in Explorer in order to assign a lock to it. Otherwise, the default lock applies.
Note that there might be locks on the fields of a parameter you create. Field locks are determined by the parameter type on which the parameter is based.