I have an interesting question on my assignment, and I need some help with it:

"Inside a PLC's inputs and outputs, you may find opto-isolators, rectifiers, triacs, BJTs and relays. For each one, explain why it can or cannot be used for the following: Digital DC Inputs; Digital DC Outputs; Digital AC Inputs; Digital AC Outputs"

Any ideas?

 

Which of the list of components confuse you as to function? Have you listed the ones that you are sure of?

 

Which of the list of components confuse you as to function? Have you listed the ones that you are sure of?

relays i assume can be output and input DC, AC would not do much good

BJT's would be for AC inputs and outputs

the other two no clue at all. I'm not 100% sure if the above are correct.

And yes these are the list of components i need to look over.

 

relays i assume can be output and input DC, AC would not do much good

why would a contact button care about passing AC or DC?

I think you need to read up a bit about transistors and triacs.