YOUR OPINION IS DESIRED

[Vetteboy]

I need experts and newbies with 10 minutes to spare to check over a lesson I wrote for my "Build A PLC Trainer" page. I would love to have lots of feedback on mistakes I've made, newbie questions, and opinions on how useful a full set of lessons might be. I'm not trying to replace other educational resources, just add a real world dimension to what's on the internet so far. So please check it out, and let me know if it's a waste of time, or helpful tool.

Lesson 1 - PLC Trainer

 

[godfrey]

Building and playing with one of these is a good way for someone to get a leg up in the PLC world. Using this to become familiar with PLCs should help one at his next job interview. He can then say he has some experience. Maybe I didn't look through the site thoroughly enough but I did not see a wiring diagram of the trainer. It would be useful to provide one.

 

[Vetteboy]

I guess with a little more time I could do up a more detailed build, with part numbers, schematics, etc. and then develop the lessons. I don't know how many people would actually build a twin to this, considering the multitude of brands out there.

 

[johnhopps]

Looks really Good.

But you need to explain how you got Instr. Pallet in the first place.

I would LLIKE TO see you watch the terms you are using....

change "HOT" to "TRUE"

eliminate any use of "NO" or "NC" to reference Bits

the student is not entering contacts or outputs, rather, he is entering different types of INSTRUCTIONS that are combined in a logic structure called a ladder rung to accomplish a desired purpose.

Finally, prior to jumping into programing, why not walk thru using RSlogic software----change windows, toolbars, open data file windows, conuter,timers, intiger, etc.... have him load a sample program, watch how the trainer works, and then introduce new instructions and solutions to new conditions by developing this basic sample prg.

 

[cypher63]

Programming a PLC is like playing chess! You might learn the moves pretty soon, but without a strategy, you will loose. By the means of the PLC-Trainer: You might want to think about some strategy before going into the program. (program structure, arranging variables, I/O interfacing etc.)
Also I think it is more than important, to have good comments (I/O, variables, rung etc.). I would try to establish some of that (unloved!) stuff.
By the way: I know that there is virtually NO documentation available about programming strategy and philosophie, but may be, someone will start it one day.......

 

[Hootnholler]

Hey CJ,

Very good, just some comments...

Obviously this is a 'primer' to PLC programming (lesson 1) and I'm sure you will expand on it as you go. As a suggestion, how about showing what happens when the contact is normally closed? Or, as the others have stated, explain the hard wiring, then how the program correlates with the circuitry?

As another has posted, there really isn't a philosophy on programming, or one that is written or adhered to. In my experiences, in my little corner of the world, I feel that there are mainly 2 types of programmers. Electricians that program and programmers that don't know electrical. Of course, quite a few of us fall outside that realm, but guessing you are trying to reach a general mass, or teach a technician how to program, so I'll go with example 1.

Show how it's wired (if you haven't all ready), use your lesson 1, but also show that the plc can do stuff without the input. Probably the biggest roadblock I see with people (like myself) is trying too hard to make it work like 'relay logic'. "If an output does not receive a certain input, it cannot function..." which is totally wrong. Maybe setup a different light for when the input is off, or a normally closed (xio), then assign the original for your xic. This may knock down a few stumbling blocks on the way to timers, counters, move functions, etc... and even some status file stuff

Hoot

 

[Vetteboy]

Thanks Guys....

Thanks Guys. I think I'll take your tips into account and do a little better job, but I'll probably wait until next winter since the nice weather only lasts a few months here.