plc programming

[courtwba1]

does any1 now of a course i can do in the west midlands,to learn how to profram plc's i am a novice

 

[SteveG]

I agree that logo's, alpha's and the like have improved over the years in terms of functions and perhaps you can get something functioning within an hour.

But my emphasis was meant to be on the word 'simple'. It implies that anyone can do it without too much effort.
It might mislead someone to have a go without realising the implications of their actions.

Firstly, machines can and do kill people. A programmer is responsible for making sure the PLC/ logo etc knows exactly what is happening all of the time
and knows what to do in the event of something happening that wasn't planned.

eg: It would be easy enough to program a cutting blade to move between 2 limit switches. The plc says - is the blade on the 'home' limit switch - yes. Has the conveyor belt stopped - yes - ok then move the blade to the 'cut' limit switch. A nice simple bit of logic and the blade cuts correctly all day.

Then one day, the contactor sticks in, the programmer didn't take any inputs from the contactor to say in or out. There was no 'motion stopped' proving device - or the 'cut' limit switch has fallen off or failed.
The cutting blade is told to go because the plc turned off the output to the conveyor contactor (but it's stuck in) or it does not know that the limit switch has fallen off - so the blade sets off at full speed maybe crashing into objects on the moving belt or then going past where the limit switch should be and smashing into whatever because the programmer didn't know to program a timer to stop the blade if the limit switch is not actuated in time.

And that example is just a small part of a fully automated machine.

So my point is and was plc programming encompasses more than the ability to press a button and make an output come on. So don't go into it lightly thinking it's not so hard.
It needs intelligence, awareness and an understanding of 'how things work' before you start on page 1

 

[Darkwood]

You are misinterpreting what i said i said you can create a simple logic programme i never misled the OP as i said anything past a very simple programme will need tutoring and i also backed this up with explaining the hardest part of PLC programming is to ensure its fail safe.... as im the only one who use the word simple i assume you refer to my posts .... im in total agreement in what you say but im confused why you creating the argument as i clearly stated the hardest part is making sure the system is fail safe , ive read through the thread a few times and it just seems you have misinterpreted it....

I learnt plc programming 4 yrs ago and im self taught...ill admit im above average in the grey matter department and i have developed complex plc controlled systems recently that has passed all fail safe/ risk assessment and my systems are talking to encoders, inverters ect and ive also linked them to the phone network for remote signalling so although i see your angle you really are preaching to the wrong person as i can suck eggs already.

Reread the posts i never said its simple 'period' as a system i only said you can easily create a simple programme quickly ... the basis of logic programming is very easy to understand and a little hurdle to get over ..implementing it into a control system is a more complex issue and requires a deeper understanding and components fail and this should be included in the risk assessment. To note here is PLC programming errors and failure should not impart risk of injury or life as with any control system...

 

[SteveG]

I'm not really having a go at you Darkwood, it's more for other readers that might come across these posts because they want to learn PLC programming.

Many electricians do want to learn it but are not sure what is required of them.

The first step would be to find out which brand of plc is prevalent in your area. There are probably 3 major players - Siemens, A Bradly and Mitsubishi.
All of these have software that is totally different even though the plc's do the same thing. (check out jobs.co.uk - if they want a programmer they want proficiency in at least one of those brands)
So you need to learn one of the market leader's software.

And if you are not allowed to learn at work, set your shop up at home and as I said before - burn the midnight oil until the fog clears. (BTW the financial rewards are great too)
Don't expect that within a day you will be up to speed, it's a long hard (but worthwhile) slog.

 

[gnuuser]

correct darkwood
its one of the reasons why i recommend the careful planning, documenting, and testing of any program before ever implementing it on a machine.
this includes testing the input and safety devices regularly and before trying a new program.