Light Sequencing

drbitboy · May 19, 2020

geniusintraining said:
Your link is not working drbitboy, you need to make it public

Ack, thought I did, just a minute ... hah, went private d'Oh! anyway, fixed now.

drbitboy · May 19, 2020

geniusintraining said:
I think daba was talking about not using counter or a timer or it would need to be more than 2 just for them

Yah I got that, but even w/o timers (e.g. STI - no timer instruction), everything I've thought of so far needs a rising edge, and generating that rising edge will use a third instruction, no?

even if I user timer.ACC as an indirect address, I still need a third instructon to reset the timer.

geniusintraining · May 19, 2020

Since you are using an Allen Bradley... one rung and one instruction

Move S42 to your output word

drbitboy · May 19, 2020

d'Oh, 60 is multiple of 12. How could I have missed that?

drbitboy · May 19, 2020

geniusintraining said:
Since you are using an Allen Bradley... one rung and one instruction

Move S42 to your output word

Nope. S42 increments every 2s in MicroLogix. And 30 is not a multiple of 12.

L D[AR2P#0.0] · May 19, 2020

Two lines of SCL code (ok wrong platform, but you get the idea). Code is run in a timed interrupt set at 1 sec.

drbitboy · May 19, 2020

Here ya go, two instructions:

https://www.youtube.com/watch?v=eeD0ATmPdIw

Not really, so if the OP uses it, they will get a failing grade because it does not meet the assignment goal.

Oh, I finally got it: the OP assignment does not have the light cycling; they just run through that sequence one time. Yeah, two instructions can do it.

drbitboy · May 19, 2020

L D[AR2 said:
Two lines of SCL code (ok wrong platform, but you get the idea). Code is run in a timed interrupt set at 1 sec.

There it is, as beautiful and simple as I knew it would be.

Thanks.

geniusintraining · May 19, 2020

drbitboy said:
Nope. S42 increments every 2s in MicroLogix. And 30 is not a multiple of 12.

Just depends on the sequence they are looking for, looks like yours turns them all on at once and the move that I use will cycle one at a time, you can also use a mask move to give a different one

drbitboy said:
There it is, as beautiful and simple as I knew it would be.

Yep LD will run circles around most of us... but using the timer and counter like the homework ask for I still like my first one, you have more control and you can change it as needed, I dont think two rungs is possible using both timers and counters

drbitboy · May 19, 2020

geniusintraining said:
I dont think two rungs is possible using both timers and counters

even with STI we still have to generate the edge.

drbitboy · May 19, 2020

drbitboy said:
1) Go watch Bernie Carlton's video series: https://www.youtube.com/watch?v=T3tnXu-Eywc

Whoops, that is Ron Beaufort's youtube; my mistake, I apologize!

PLCnovice61 · May 19, 2020

In GT's example, OP never said what the time frame could be, so he's the winner.

OkiePC · May 19, 2020

geniusintraining said:
Just depends on the sequence they are looking for, looks like yours turns them all on at once and the move that I use will cycle one at a time, you can also use a mask move to give a different one

Yep LD will run circles around most of us... but using the timer and counter like the homework ask for I still like my first one, you have more control and you can change it as needed, I dont think two rungs is possible using both timers and counters

If you use a PLC that supports the CPT block and a long enough expression including modulo, you can probably do this with one instruction and get the sequence correct.

Throw a dummy timer and counter in there to meet instructor requirements, and now we're at three instructions...
This is something I would do in a classroom setting just to be contrarian...

In real life, I'd use indirect addressing and a handful of rungs...adjustable time interval, change the bit table for new patterns, maximize flexibility.

ASF · May 19, 2020

drbitboy said:
even with STI we still have to generate the edge.

You're thinking the right way, just keep thinking. Why do we have to generate the edge? And how does the instruction know we've generated it?

I won't spoil it for you, you're a smart cookie

parky · May 20, 2020

Lets keep it real guys, the OP wants some guidance on writing a program with certain criteria, this is turning into a competition of who can write the smallest code and ignoring the OP's dilemma. Modern PLC's have plenty of memory and generally fast enough for most scenarios Let him start with baby steps and keep it to the point.

Light Sequencing

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