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About DEVO

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  • Birthday 09/02/64

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  1. Typically I program everything in Contrologix using the continuous task. I have been looking at some of the other options but I don't see too much info on why you might choose one type of task (event, periodic, motion) over another. The motion task seemed the most straight forward, but then I have seen where it was suggested to use an event driven task and run it off of the motion update. The periodic task can be used for PID execution but I have never had a use for it otherwise. I was just wondering what others use the different tasks for and why. As usual Rockwell is pretty vague on the subject. Thanks!
  2. Ah, nice lead! These are PC based systems it seems; do you know what the pricing is like for a low end CPU? How about expansion modules? I wouldn't be opposed to having ladder as an option, its just that I want C as an option too. thanks, -Holly
  3. Take a look at B&R PLC's: Their software, Automation Studio, allows you to use either ladder logic, C programming, Instruction List, Sequential Function Chart and Structured Text. They have a lot of options for hardware and HMI's. Don't count out using ladder logic for some of the machine control, it is straight forward, easy for others to follow and almost everyone in the automation industry is familiar with it. Good Luck.
  4. rsview 32

    I don't remember exactly what I did but I know it was something like this. You need to go to where the path is stored. Save the current one to a text file and then remove all the paths except the basic ones. Intall RSView and then go back and restore you old path. This has been a problem with AB for awhile, I think their may even be a knowledge base about it.
  5. Most larger companies will do some sort of testing, either written, hands-on or both to evaluate your skills. Just try to get as much hands on experience as you can. Reading it in a book is not the same as putting into practice.
  6. As a degreed electrical engineer with more than 20 years experience in the controls/manufacturing industry, I would suggest the ECM program. A typical position for someone with that background would be maintenance at a manufacturing facility. You would be troubleshooting problems with the equipment, working on retrofits to old equipment, and having PLC experience would be a big plus to any employer since most new equipment comes with a PLC. The downside can be that you may be required to work 2nd or 3rd shift, although this means a higher salary and there is usually a lot of overtime involved.
  7. B&R Automation Studio -- how to run a project?

    I have not actually done it myself, but I believe if you go to the help section and search simulation or I/O simulation you will find some information on how to setup a test project and simulate IO.
  8. I agree with BobLfoot, what you wrote sounds right. As for creating a history chart, since you did not mention which PLC you are using so I will us the SLC500, what I have usally done is to select an area of memory for these readings, say N7:0-99, this would allow you to store the last 100 readings. You could either create a pointer and use index addressing, so the first reading goes into N7:0 then increment the pointer and the next reading will go in N7:1, etc.. Once you reach N7:99, you would reset the pointer and start back at N7:0. Or if you want N7:0 to always have the last reading, then you would need to move the values from N7:0-N7:98 into N7:1-N7:99, not too hard with indexed addressing. Then store your latest reading in N7:0.
  9. What exactly is your question? Is it how to check if the analog input is reading OK? Since you know that the signal should change very slowly, I would suggest some sort of rate of change check. For instance if you see a count increase or decrease of x within so many seconds then flag the signal as suspect and alert the operator. If there is a "safe" reading, you could then move this value into the register or latch a bit to inhibit the process from continuing until the reliability of the reading is confirmed. This would be similiar to how a thermocouple reads upscale when a burnout occurs. Another thought would be to have a second sensor on the machine and brought into the PLC to use as a comparison and then give the operator the ability to select which sensor would be used for the process.
  10. Converting Ialian schematics

    Thanks for the info. It will make my job much easier.
  11. We have been given the task of retrofitting the proprietary controls of an Italian Wrapping machine. We will be replacing the control boards with an AB PLC and they would also like us to convert the schematics. The schematics are currently drawn in the European style and there are some symbols I am unfamiliar wiith. I was wondering if anyone knows where I can get something that woul identify the common symbols used or give the equivalent in US standards. For instance I know that K is used to represent a relay and H is for an indicator (light, horn). I have tried an internet search but haven't found anything useful yet.
  12. RS Linx "Fix"

    I just had to do this while working on a DeviceNet system using RSNetworx. While setting the nodes the software stopped recognizing the latest device i connected to the system. I eventually called tech support and they had me do the same thing. Apparently these files can get corrupted pretty easily and then will fail to shut down when RSLinx is shutdown.
  13. I run RSLinx version (CPR 7) and under the communcation drivers, there is a selection for 1747-PIC/AIC+ Driver. Perhaps you should consider upgrading your RSLinx.
  14. I always need to carry a laptop, cables, a couple of tools, paperwork and sometimes it involves going into some pretty harsh environments. I also have a bad back so carrying the case all the time is out of the question. Unfortunately the previous cases I bought, had small wheels which caused problems with balance and did not last long when I needed to roll it across a dirt parking lot on a job site. I did some research and wound up choosing a Kensington Contour Roller. It has large wheels, a telescoping handle and the whole case is ergonomically designed to lay against your side when carrying it over the shoulder. I've had it for a couple of months now and it has worked out great. It was about $100 but well worth the cost.
  15. Why not just use a NC contact on the pushbutton and put it in series with the output such that when the button is pressed to energize the horn, the circuit to the horn from the PLC is opened. We do this all the time.