B&B Electronics VFG3000 - Manual - Manual (Page 186)

S ECURITY B ASICS V LINX F IELDBUS G ATEWAY M ANAGER U SER M ANUAL
P AGE 170
U
SER
R
IGHTS
Each user is granted zero or more access rights. A user with no rights can access those objects
that merely require the identity of the user to be recorded, whereas users with more rights can
access those objects that demand those rights to be present. Rights are divided into System
Rights and User Rights, with the former controlling access to facilities within the Fieldbus
Gateway Manager software, and the latter being available for general use. For example, User
Right 1 might be used within your database to control access to production targets; only users
whom you want to be able to vary such things would then be assigned this right.
A CCESS C ONTROL
Objects that are subject to security have an associated access control setting…
This setting allows you to specify whether the item can be accessed by anyone, by any
operator whose identity is known, or by users with specific user rights. The access control
setting also allows you to specify whether a tag can be changed by a program running as a
result of something other than user action. This facility allows you to guarantee that no
background changes occur to sensitive data, even if a programming error attempts to make
such a change.
W RITE L OGGING
Tags also have a write logging property...
This indicates whether changes made to a tag by users or by programs should be logged. This
facility allows you to create an audit trail of changes to your system, thereby simplifying fault
finding and providing quality-control information as to process configuration. Note that care
should be taken when logging changes made by programs, as certain database may log
unmanageable amounts of data in such circumstances.