wheres the best place to start?

[hxsarge]

sorry for those of you who have prior knowledge of these sorts of things but here goes...

I have been working around machinery and older plant equipment for a few years now, but im wanting to learn more about plc's and siemens in particular. ive done some research but i think the best way for me to learn a bit more is to have a go, so i was thinking of buying a cheep second hand plc on ebay and buying some rather expensive software and building a rig in my garage to have play. has anyone else started like this? any recommendations etc? thanks

 

[ProDave]

Have a look at Your Personal PLC Tutor - Learn PLC Programming Here. FREE lots of info there.

Unfortunately choosing Siemens to learn on, is probably the most difficult, because the software to program them is somewhat expensive.

It depends what you mean by cheap. I had a load of Siemens S7 stuff given to me when my last employer had a clear out. I played with it at home for a bit but eventually sold it all on ebay. Going by what I got when I sold my kit, to get a working Siemens PLC and a useful selection of I/O modules is going to cost you a couple of hundred.

There are other makes of PLC that provide free, or cheap programming software and those might be a far better bet for learning on at home.

 

[hxsarge]

hey cheers for that, ive been self teaching my self from that site for a few weeks now(always dangerous), im ok with the theory, iv even converted wiring diagrams to plc logic a few times just for fun. im wanting to get some practical experience in really. im going to use some old limit switches and old motors i have about the place, just to carry on teaching myself practically. only problem is i really have no idea what a plc physically consists of when im looking around. i could do with someone pointing me in the direction of a unit and some software. not really bothered if its siemens or cheep 3rd party stuff, just looking to play. ive been on ebay and to be honest im not sure whats what.

 

[ProDave]

How deep are your pockets?

this will get you started programming Siemens PLC's SIEMENS S7 300 PLC PROGRAMMING KIT CPU312C PLC+NEW USB PROG CABLE+S7 PRO V5.4 | eBay

One of the "micro" PLC's is a lot cheaper SIEMENS LOGO! SYSTEM PLC STARTER KIT 230 0BA6 6ED1057-3BA02-0AA6 IP20 NEW | eBay but they tend to be programmed quite different to the bigger ones so may not teach you what you really need to know.

Generally the micro PLC's are an all in one unit with the processor and I/O all in one.

And generally the larger PLC's, you need a processor module and some I/O modules, and a bus or rack to mount them all on, but the first example of the Siemens PLC has some built in I/O so can be used stand alone.

If you do get into the Siemens S7300 series I have a very small amount of stuff left over, mostly just connectors and stuff, no actual PLC's or I/O modules.

 

[hxsarge]

thanks mate, really helped explain things did that! i mostly see the micro plcs in smaller woodworking machines and door systems etc, i think i might start there and work my way up, its more of a hobby than anything, but i have been talking to a few people in maintenance jobs in heavy industry and this is how they started, most maintenance jobs require some prior knowledge i am led to believe.

 

[ProDave]

What is your motivation for wanting to "learn PLC's"?

Is it because you want to eventually make a career out of it?

Or is it JUST that you like tinkering with stuff and want to be able to program something to control something (boys toys)?

If the latter, forget PLC's, consider something like the Aruino. A little microcontroller module you can buy on ebay for

 

[Technician]

Programmable Logic Computers and knowledge of them

are just other strings to the bows of any decent spark.

Great heavens, there are enough of them on this forum.

I started with valves and then TTL logic.

I cannot imagine anyone taking on work of this nature and

hoping to make a living at it; not unless you would seek

to undertake a design role, making the product subject to

patent/copyright for a period and hope that no-one would

subvert your good intentions.

Remember Moore's Law; that the memory of a computer doubles

every two years.

Moore's law - Wikipedia, the free encyclopedia.

When working with Hospital Radio in Leeds I was asked if

I would have a look at a UHER tape machine. I marvelled at

its wonderful, folded circuit board construction. I cleaned

the mechanisms, scraped the oxide off the capstans, cleaned the

brakes and de-gaussed the heads and handed it back. I did all

that for nothing because it was a registered charity. The owner

of the machine said it had never been better.

I have cracked a few problems in my time: with a bit of

ingenuity and a bit of grey matter; PLC's may seem to be

the way, but people present the business that is ALWAYS

renewable.