Modular and rack

1 What is a typical industrial application for a modular or rack mouted PLC?

2 What is the sequence of operations that occur during programme scanning in a programmable controller?

3 What is the purpose of OPTO - ISOLATION?


I am very new to PLCS. Ive just recieved a 50 question paper. These are just ones i could not find any information on. I would really appreciate any help or pointers to goods websites with general information on PLCS.

Thankyou

2 What is the sequence of operations that occur during programme scanning in a programmable controller?

3 What is the purpose of OPTO - ISOLATION?




I have answers for 2 and 3.

2. visit this website's tutorials (learn PLCs link and u will have the exact answer in that).

3. Opto-Isolation prevents damaging ground loops. Optical-isolation circuits convert electrical signals to light and back again, to keep signal noise andground loops from crossing between parts of your network. That means the electrical noise from your factory floorwon't affect your office communications, and the difference in groundpotential over long distances and between buildings won't damage your sensitive equipment.

taknevs

There was a big discussion on this forum just last week about opto-isolation. If you do a search for it you will find your answer to that question.