If your industrial controls system becomes infected with some kind of malware, a worm may disable software-controlled safety features by a variety of means. You might examine your control system programming and conclude that it's simply not possible for Motor 3A to start when the system is in maintenance mode and administratively locked out. The problem is, a worm could rewrite the control logic and/or open administrative locks.

The solution is to add mechanical safety means, which is a best practice anyhow. For example, don't lock out the motor only from the software. Add the step of opening the disconnect and physically locking it out. Make a point of isolating every possible energy source. This doesn't mean just electrical energy sources. For example, lower the punch press to its bottom of stroke position to remove the kinetic energy it would have if stopped at its top stroke position.

Although an industrial process can be fully automated, safety cannot.