Electronic signatures are user names and passwords that provide accountability for operator writes to certain module parameters and fields from DeltaV Live, DeltaV Operate, and Control Studio online. Electronic Signatures do not apply to writes to OPC and to the DeltaV Excel Add-in application. Electronic signatures is a DeltaV system preference that can be disabled (hidden) if not required or enabled selectively on an area-by-area, module-by-module basis. Electronic signatures does not change the existing DeltaV security feature that controls who is able to make changes to parameters. Rather, it uses a signature to authenticate the operator's identity. That is, the signature is used as an additional check to ensure that the operator is who he claims to be. The operator must have a valid user name and password and the required privileges to perform the action in the area in which the module resides. The write is not allowed if the operator fails to enter a valid username and password and if the operator does not have the required privileges in the area in which the module resides.
Depending upon the criticality of a module to the process, no signature, one signature (confirmer), or two signatures (confirmer and verifier) can be configured. It is possible to allow the same person to be both the confirmer and verifier of an operator write. Typically, the verifier is a higher-level employee whose signature approves the change the confirmer is making. The verifier must hold the key to the ACTION_VERIFY function lock. To allow the same person to be both Confirmer and Verifier, select Properties from the Electronic Signatures context menu and select the check box. If the electronic signature succeeds, the date and time the electronic signature authentication occurred, the node from which the change occurred, a description of the action, and the confirmer and verifier names are recorded in the Event Chronicle and can be seen through the Process History View application. Similarly, failed attempts at confirming or verifying an action are also recorded and visible through the Process History View. In addition to the Process History View application, failed confirm or verify attempts are also recorded in the Batch Historian if it is collecting Event Chronicle events and can be viewed through the Batch History View application.
Operator comments
The operator has the option of entering a comment about the parameter change. Operator comments are recorded in the Desc2 field in the Process History View application. This field is truncated at 240 characters. By default, the system adds the string VALUE SIGNED FOR = xxxxx before the comment. That is, the system adds additional characters to your comment and these additional characters are counted in the 240 character limit. So for example if you changed a value to 365 and entered the comment "changed value for tank1" the Desc2 field will total 48 characters and read:
VALUE SIGNED FOR = 365 (changed value for tank1)
The system calculates the length of the string VALUE SIGNED FOR = xxxxx plus the length of the comment. If the comment will cause Desc2 to exceed 240 characters, the system posts a message asking that the comment be shortened. The length of the comment is limited to the lesser of: 200 characters or what fits in the Desc2 field. If VALUE SIGNED FOR is a string that exceeds that 240 characters, the value is truncated at 240 characters in the Desc2 field in Process History View and no comment is saved with the value.
The DeltaV system does not enforce the use of operator comments; this decision is left to plant managers.
Do not use the ENTER key to create a line break in the Comment field. Pressing the ENTER key in the Comment field is the same as selecting the OK button; it dismisses the dialog and performs the command.