newbie factory guy - intro and questions

Hello! I am new to PLC's but have a need and desire to learn. I work in a factory that makes textile related products, the variety of products and styles of production requires flexible sewing workstations.

I have a mentor here that has several decades worth of experience in sewing factories but he does not know computers and current types of sensors so I am on my own for this.

I bought an AD click unit and set up some test boards to try and learn, other than whats on this site, what are some recommendations for learning PLC's. Also I have my first application that I would like to use a PLC for.

I got the idea after watching this video. Please look at 1:38 for about 30 seconds after
http://www.youtube.com/watch?v=jV07wLxQKMc

The two spinning disks are being used to sense thread being consumed by the sewing machine. I believe it is a prox sensor watching a marker in the plastic. How would you program something like this? Is this a counter or timer function? There are three differnet states that could be seen.

1. The disk could be stopped if the thread is broken
2. The disk could be spinning at a slower then normal speed when the thread breaks but is still caught on the material
3. The disk could be spinning at normal speed.

I appreciate any help and direction. Please make sure you talk to me like I am a 2 year old. I wont be offended.

Thanks in advance,

Jason

Jason - Welcome to the site. You have come to the right place. You should be able to get a really good start here especially if you use the resources listed at the top of the page and continue to show your efforts. We get a lot of "do my homework for me" questions so demonstrating effort is a must before a lot of folks are willing to offer up too much.

On to your problem.

I can't view videos from youtube here at work, but your description seems adequate if I understand it correctly. Furthermore it sounds like a perfect application for a small PLC.

My (blind) observation is that you are exactly correct - a prox is looking for a marker to identify the disk is rotating. What you would do is take the feedback from this prox into a PLC input and then watch it using two timers. The first timer would set so that it would time out if the pulses came just a little be later than normal speed. This would indicate a slow but running system. The second timer would be set to time out if a pulse does not come for a long time. This indicates a broken thread. In each case, the pulse from the prox would reset the timer and you simply monitor whether either timer times out.

Steve

Thanks Steve, I definitely have to struggle through this, but just a point in the right direction is all I need. If I fail, then I may need the answer to the test.

I appreciate the direction! I will let you know if I succeed of fail.

Your logic seeme spot on. I my work we have some sack closing stitchers, just as you describe but I have never looked in the program. I am sure that if the stitcher is running, the thread sensors have to toggle. We have two threads and the rear thread runs more slowly than the front.

Thanks Markie. The machine in question has 4 threads, similar to your bag closer it is a thread for the needle and a thread in a part that interloops with the needle thread. I was planning on only monitoring two of the sensors because if one of the looper threads has a problem, the needle thread will reflect that with a speed change.

Same with the video, that is a 3 thread machine but they are only watching two threads. One of the two will show a change if any of the three has a problem.

Thanks again.

Jason

Jason
I am in the same boat as you. I am a Maint tech at a mill work facility, That no longer has Instrumentation/ controls support.
Everything I have learned is from staring over outside guys shoulders, reading (the google and oem websites) or trial and error.
I have taken a few classes,but what has worked best for me is hands on.
I won't speak up a particular mfg. I went with a two letter brand that is predominant in my facility. I got free starter software from their website and purchased their smallest plc off ebay for less than $100.
On my off time I tinker and play with it at home. I have the advantage of the full software pkg at work, so I can take my real world problems and try to find solutions without running the risk of causing downtime.
I am far from being a plc guy, but this has helped me.
Regards
OlSQ.

Revolutions Per Minute

Jason, Check out Attachment It's Logic to Detect Real time RPM and some explanation. This was my first Thought after watching your Video.

Thank you for the help and direction. Early on I got stuck using Emersons Unidrive platform for servo control and have not yet tried to use their PLC plugin module. Any reason to stay away from it?

Which company seems to support their product the best? This is going to be the most important for me as I get up to speed.

Thanks again,

Jason

Thanks Cwal for writing that up! Very helpful.


Jason

Hello

In my opnion Emerson seems to have really good support. A few years ago I wrote my first motion control program (out of the pan and into the fire) using a UniDrive SP and an EZ-Motion module. I called tech support and got afew pointers after researching of course, but got a call out of the blue the rep called me back later that night just to see how it was going and proceeded to assist me for a few hours. Now that I call SUPPORT.

Thank You Eric.

Tom