Safe Commands

What are Safe Commands?

In SCADA systems it may lead to very critical situations if unintended or wrong commands are being sent by operating personnel. This calls for a security check before commands are allowed to be sent to the PLCs.

IGSS Safe Commands allows flexible control of commands being sent to the process PLCs without any use of VBA. Three levels of Safe Commands are provided:

Level 1

The basic safety precaution is to require the person to confirm an operation when issuing PLC commands. This scenario is shown below, where the operator has ordered the pump, p1, to STOP.

Using the Safe Command "Confirm" where operators must confirm the issued command.

Level 2

Some objects may be restricted so that only a certain person should be allowed to send PLC commands to this special object. Safe Commands can then be applied to require a username and password, before a command may be issued to the PLC. User access rights are then controlled in the User Administration module.

Using the Safe Command "Confirm with Password" where operators must give username and password to issue commands.

Level 3

Some critical process objects may even require that a second person also authorizes the command before this may be issued.

Using the Safe Command "Confirm by two Users" where two authorized personnel must allow the command.

Applying Safe Commands

Safe Commands are applied individually for each IGSS object. This allows maximum flexibility in setting up a secure operation of the SCADA system.