Anti -Tie Down - Non Repeat - No Timer

[OkiePC]

Counting and timing without counter or timers.

This one should allow a 4 scan tolerance on button press timing. I tried testing it out with CGM buttons and was able to prove it works with RSLogix500 Emulate.

I changed the CPU to a 5/05 and addresses to match the assignment too, so it will no longer run (as addressed) in RSLogix Micro Starter Lite (Free) Edition or whatever it is named this month.

The seal in branch may need to go away or be replaced with something a little different to satisfy the instructor, and the XIO "TDC" is fictitious at the moment.

"Look Ma, two hands, no timers or counters..."

 

[raydog26]

wow that's a crazy looking circuit. i am certainly gonna test that out and see how it works. how long did it take you to write that one lol

 

[OkiePC]

About 20-30 minutes, but I have been doing this for awhile...it took longer to make the screen images and figure out how to show them within the thread.

 

[raydog26]

man I hope I can do that so quickly some day lol.

 

[OkiePC]

Windows shortcut keys are your friend. You can use them on branches, (already populated with blank instructions or partially addressed ones). You can group select by holding down shift or control keys and select groups of instructions, branches, and rungs. Then copy to the windows clipboard (CTRL+C, CTRL + X to Cut) and paste (CTRL+V). Note that if you past branches on a rung with no branches already there, they will be concatenated in series instead. No problem, just click the branch icon and a branch appears. then past on the branch and they will look just like the original branches. The cursor keys with shift and control are your keyboard selection tools.

Don't forget to use HOME, END, CTRL+HOME, CTRL+END, etc.

The mouse I mainly use when I need to highlight a text field or for online editing, I leave it parked by the control buttons, and use the keyboard exclusively for navigation. I have memorized patterns of keystrokes to, for example, jump to the first operand in the first branch output instruction three rungs up...It takes like .3 seconds to type that movement.

Try this: put the cursor (little red square) on the left corner of a branch with some instructions on it and hit CTRL+C, then hold down CTRL with your left pinky and hit "V" ten times with your left forefinger..

Do some dragging and dropping too, and pay real close attention to all the little red and green dots that appear and what happens to the dropped rungs when you "let go" of the instruction (or address, or rung or branch).

Also, try to minimize mouse movement and having to take your hand off it or reach for it too frequently. Use lefthand shortcut keys, and learn where to park your mouse. Use multiple data table windows, and size them so your pointer motion (to drag and drop them on blank ladder) is minimal.

Farg up a rung real bad and make a mess? No prob. if offline, just hit CTRL+Z a bunch of times. Online ...don't farg up online. just don't...

OT: I need to make some videos for RSLogix. I have one in a thread at MrPLC I think. I have so many shortcuts, I need to video myself and watch because I don't even know what I am doing with both hands sometimes; it's so unconscious.

I think a combination of Cam studio and Windows Movie Maker should make for cheap and easy video editing any other suggestions? I would like one that allowed me to show the mouse and keyboard activity during playback...not sure I can pull that off with tools on hand...

 

[raydog26]

I didn't think you could use the keyboard for just about everything... i am always using my mouse to click and drag and what not.. no wonder it takes me so damn long to write simple code. I am certainly going to practice from here on out using keyboard commands and hope to get faster.

some instructional videos would be great. I mainly use windows movie maker for editing when i need to but i am sure you could find some other free ware online for editing videos too.

 

[OkiePC]

I have not watched Ron Beaufort's videos all the way through, but for a student, they are highly recommended.

http://www.ronbeaufort.com/sample_lessons.htm

 

[raydog26]

cool thanks. i will certainly look those over. I am willing to study ll i can to help myself better understand this.

i tried your first example you gave me on the first page in the PLC simulator on this site and it didn't seem to function how i needed it. when i let off one button and still hold the other it allowed me to turn on output and not having to release both buttons.

 

[OkiePC]

it didn't seem to function how i needed it. when i let off one button and still hold the other it allowed me to turn on output and not having to release both buttons.

That's the seal in circuit but it should drop out though, as soon as you release either real button...they're in series on the output rung...

Also, I think it is only three scans of offset between button presses, not four. I need to run it in single scan mode on the Emulator.

You can get RSLogix Free and the Emulator too, and convert the program back to Micrologix addressing temporarily...good time to learn about search and replace...or practice entering code with the editor.

The scan time in RSLogix Emulator is not realistic, but close, and the program scan of normal logic is accurate. It won't do online editing, PID loops or communications, but otherwise, looks like a DF1 Micrologix in RSLinx/Logix500. I have not used thet simulator on this site in a long time, and certainly not for anything tricky like oneshots without special instructions like my example...not sure if the site emulator is realistic enough to do that like a real SLC/PLC-5.

 

[leitmotif]

My Professor is actually the dean of the entire program/building. I think the man reason for this exercise is to show the importance of writing a code that is safe for the operator because if it is wrong injury and/or death can occur. He has been working with PLC's for over 30 years teaching and for companies both in that time.

For the students that quit in college its hard to make them change their mind once its made up especially they don't need to talk to him in order to quit you just submit 1 form to admissions and you never have to go back. no contact with the teacher is needed.

My thoughts
1. I care not if he is the dean. If so he should be doubly chastised in my opinion for poor leadership of faculty and playing games with students.
2. Colleger faculty should remember that students are paying their wages in whole or part. Regardless they are STILL students' employees.
3. Homework should challenge the brain. It is learning after all.
4. I can definitely agree with the argument that assignments like this should be realistic and closely mimic what the real world does.
5. I can also to a limited point agree with the instructor and make the students do some thinking. By denying timers he is making the challenge tougher. An A+ should allow for "it cannot be done safely for following reasons" BUT the student must have good reasons of course.
6. With a MS BS AA and graduate of Navy Nuclear Power Training I think I am qualified to comment - I should know a bit about studenting by now.
7. I also teach so I am sort of qualified on that side also.

Dan Bentler

 

[raydog26]

OkiePC: Thanks I will get the emulator and give it a try. Monday i plan to stop by the college early and try these all out on the PLC's there. this is the downside to assignments at home they cant really be tested.

Dan: I couldn't agree more with the points you made. As a paying student overall i think he has been doing good. a hell of a lot better then some other college professors i had in the past.but your points are valid for sure.

 

[OkiePC]

OkiePC: Thanks

You're welcome.

I will get the emulator and give it a try.

http://forums.mrplc.com/index.php?showtopic=12217

Monday i plan to stop by the college early and try these all out on the PLC's there. this is the downside to assignments at home they cant really be tested.

Yep.. They can with the software in the link above.

Dan: I couldn't agree more with the points you made. As a paying student overall i think he has been doing good. a hell of a lot better then some other college professors i had in the past.but your points are valid for sure.

It is always a bad idea to use terms reserved for safety circuits when teaching beginners. There are so many other more applicable and up to date examples he should focus on. That's my last 2 cents about criticizing this choice of exercise.

I just watched Ron's first 6 videos, and they are really, really good.

 

[jstolaruk]

Back to the OP, I'm surprised that using a counter as a timer is not embraced. Increment a counter every other scan and when it hits the preset, the elapsed time it took it to finish is approximately 2*scan time*counter.preset.

Some experimenting would have to be done to get a preset value that works, but I've seen this method used in the real world back when PLC's had a limited number of timers and they were all used up.

 

[raydog26]

Jstolaruk: I think the main reason we cant use timer and counters yet is he hasn't taught them too us. We just started to cover timers last monday and he said he will cover it for a few classes to make sure we understand it because many students say they do but really dont so he takes extra time to drill it into our heads. then next week we start counters.

 

[TurpoUrpo]

For last time I am arguing that they have been taught so basic things for now, that it would be too much from their teacher to ask to do "timer" themselves and only thing required is to make sure that both buttons are depressed before pressed again. Ofc that really is not anti tie down as we see it, but it does defeat only one button usage.