PLC Flashcards
How come a circuit with a power source, a sensor switch, and a plc io at the end doesn’t short out?
The plc doesn’t act as a neutral bus bar; it acts as a load and a neutral bus bar in that power goes through a switch and then into the plc directly, without a load in the middle. The plc itself acts as a load.
Describe an XIO instruction with examples.
XIO means examine if open, or HAPPY if open. Think of the line in the middle |/| as the open handle-looking line of a switch on a schematic.
If the go switch of a side travel corresponding to an XIO instruction is not green, that means the XIO is NOT happy, which means it’s not open, which means the side travel switch is closed, which means the arm above the go switch is above it, which means the belt is not misaligned.
Basically, the system is happy, but the XIO is not happy, which is what we want. Happy doesn’t mean good.
Why is it bad to reset a plc alarm on the program itself?
The company wants us to reset from one central hub; we don’t want to lose jobs.
How to AFI a rung?
Start rung edits. Then add the AFI bit after selecting it up top (where the branches are; sort through the menus). Add it. Then test it. Then accept/append edits. (MAYBE HAVE TO ACCEPT EDITS BEFORE TESTING? Unlikely though)
The rung with the e’s (the top rung) is the one to edit.
