PLC Questions

google.

Have done to no avail.

This REALLY, REALLY feels like a homework question.

Fine then (I am feeling really generous). Try looking up information regarding different cabling types - coax cable, fibre-optic cable. Network is, well advantages/disadvantages of linking PLC's in a network type arrangement rather than single point-to-point. All these questions boil down to the same generic question -

NAME THE ADVANTAGES AND DISADVANTAGES OF THE FOLLOWING CABLE TYPES.

Funnily enough I had the same question arise when I did my cert and degree in engineering (funny because network is not a cable type at all but a topology). It really is a small world.

Use of internet search engines and knowing the applicable terms to input into said engines is a VITAL part of modern data search and learning techniques. A good way to start is to look at electrical cataloges (I dont know what country your in), from there you can learn cable manufacturer names, from there you can get datasheets and design notes from their websites. Keep trying.

Back in my day (which was not a particuarly long time ago) all we had were books. Ahhh progress.

This gets 792 responses.

Browse them and find the answers.

http://www.google.ca/search?hl=en&q=%22plc+communication%22+%2Bmethods&btnG=Search&meta=

Hi Chaps,

Thank you for your reply`s, yes the questions are from doing my second year HNC.

Can't comment on co-axial but ..

Fibre optics

Pros - hi speed, excellent plc isolation from over voltage and electrical noise, long distance possible

Cons - expensive, difficult to DIY.

Network (I assume you mean wire RS232 and RS485)

Pros - Cheap (50 cents/metre), easy to DIY, most PLC have native RS232 or RS485 ports

Cons - Must put in fuseable links between the PLC"s and the network otherwise if one gets an overvoltage they ALL get cooked. SLower data rates. Noise can be an issue unless you pay a lot of attention to shielding & grounding especially in a noisy industrial environment. Distance is much shorter (10m RS232, approx 200m for RS485).

Hope this helps

I can tell you one thing about Coaxial cables, they tend to act as big antenas if you run them through just about any noisy environment. That includes current, magnetic or even RF. That's why most places are switching to fiber, there is no noise issues. The only problem with fiber is the equipment is so expensive.

As for network, I'm assuming you mean running Cat-5 or Cat-6 Ethernet cables. Those are good if your running any time of IP device controllers, but the lengths of your cable runs is much smaller than with the other types. People tend to need repeaters or line drivers for them to have the signal make it to the destination.

I appreciate all of your help, but could you help me on a couple more.

I have to describe the operational characteristics of a plc in terms of.

Scanning

Performing logic operations

Continuous updating

Mass i/o copying

Any body.