Ken M,
My post was directed to Git. I was trying to keep it simple for the sake of explanation. I believe I made it very clear that my post was a comparison between Ladder and Hardwire. With respect to Ladder, I indicated in my post that a scan-time of 0.000 secs is unobtainable. I tried to, at least, imply that you are more likely to get what is effectively a 0.000 scan-time in Hardwire than Ladder, as described below.
In a hardwired application, the speed of a signal is essentially the speed of light. If logical circumstances call for a signal to be applied to one or more output devices, then those devices become influenced by that signal at the speed of light. The devices then respond, each at their own inherent speed.
The point being, in a PLC, Inputs are read, decisions are made, and then outputs are acted on. There is a time-delay between reading the inputs, from scan-to-scan. Then, there is a time difference between reading the inputs and writing the outputs. And that time is less than the total scan-time, but, overall, it is still slower than a hardwired system.
Let's say you have a single input controlling a single output.
In Ladder...
Read the Input, Process the rung, Write the Output.
If the input was NOT on during the last read, and is then seen to be on in the next (current) read, then the input had to have come on sometime between the last read and the current read.
In Hardwire...
Before the PLC detects that the input has come on, the hardwired system is already responding to the hot input and applying power to the output device.
That is the "real-time" to which I referred. And that is the difference that I was trying to point out.
Of course, there is latency in any system (except for maybe those ESP Systems related to Quantum Mechanics). As far as I know, there is no such thing as an INSTANT system, but there is a Real-Time Electrical System that is NOT artificially delayed.
Subtle... but, oh, so real!