"PLC systems are designed by electrical engineers who started out in that or something else and don't know about much on the Joel Test. But I can be proven wrong."
That's probably true, given that PLCs were originally for electrical engineers as means of having "software relays". The concept of computer engineers came much later, and for computer science, they typically have zero electrical background which means that even if they program really well, it can be the case that they don't understand the physical implications of the code that they've just written.
In computer science, writing True might mean it's magically on, but in real life, a valve actually has a small delay before it physically is open. So a time delay has to be placed on the output. That's a simple example, but there are other such nuances of electrical/physical devices. Also, much of PLC programming (especially in process control) is control theory (PID controllers, essentially differential equations so that devices actuate "smoothly" instead of in a "jerky" manner). This also seems to not be covered in a CS curriculum.
It's not really that big a deal to grasp the physical implications of code and timing. Any network code will have the same issue, i.e., any web coding.
The industrial controls industry has a very 1980s/1990s attitude for cybersecurity. I don't envy the public-facing engineers working for the vendors.
That's probably true, given that PLCs were originally for electrical engineers as means of having "software relays". The concept of computer engineers came much later, and for computer science, they typically have zero electrical background which means that even if they program really well, it can be the case that they don't understand the physical implications of the code that they've just written.
In computer science, writing True might mean it's magically on, but in real life, a valve actually has a small delay before it physically is open. So a time delay has to be placed on the output. That's a simple example, but there are other such nuances of electrical/physical devices. Also, much of PLC programming (especially in process control) is control theory (PID controllers, essentially differential equations so that devices actuate "smoothly" instead of in a "jerky" manner). This also seems to not be covered in a CS curriculum.