drforsythe

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Posts posted by drforsythe

  1. Posted

    I second the idea to use a FX3U. Since you already have the Mitsubishi experience, that might be your best bet. I have used the predecessor to the FX3U in a simple coil wrapping application. In the case of my project, the servo amplifier (MR-J2 at the time) closed the loop and the plc was 'blind' to actual position. We could have added additional feedback to the plc for verification, but the application was so simple we chose not to. The drive did a great job of positioning our product for assembly.

  2. Posted

    I understand and agree with Okie's comments regarding PCs on the plant floor. That aside, we currently have five twinscrew extruders running RSView 32. The control system not only controls the extruder, but also the feed stream and refill system. This requires us to have a display on the main extruder panel (on ground level) and another on the feeder level (upstairs). We currently accomplish this using a keyboard/video/mouse (KVM) extender from Black Box. This particular KVM runs us about $900 and includes the main unit and one remote station. The main unit is powered by the PC and the remote unit is powered with a 110vac power adapter. Communication between the units is a single cat. 5 ethernet cable. We only use the video and touchscreen signals, but we could also have a remote keyboard if we chose to. Hopefully this info is helpful.

  3. Posted

    It has been years since I regularly worked with Mitsubishi and Beijers products, but does the E615 have transparent mode? If it does, could a SCADA system be hooked up through the 615? Again, it has been a while, so I am not sure if it could be done or not. I used to use transparent mode on the older Beijers products to use one RS232 port to program both the PLC and the HMI. Best of luck.

  7. Posted

    It is an approved method. The key to the licenses is that only one can be used at a time. As a developer, you are entitled to use your development license (Works) on the unit you are developing the application on. Once development is complete, you use your license elsewhere. You are still required to have a license on the Runtime PC, so the only one being moved is the Works license. Rockwell has a good handle on how their licenses are issued, especially now that the Master Disks are no longer made for new purchases.

  8. Posted

    Daryl: Yes, purchase 1 Works license for you and move it dynamically as you develop each project. Then purchase a Runtime license for each machine that will be running an application in RSV32. This significantly reduces your costs. Just don't forget to remove your Works license when your project is complete!

  9. Posted

    I like to have both options open. I have my license for RSV32 Works for developing the application on traveling media like a USB drive or a floppy disk. When I install RSV on the PC that will run the application, I always choose to install RSV Works instead of just Runtime. This allows me to develop the application on the machine that will ultimately run it, but it also allows Runtime to run if the license is present. When I am finished with the app, I will then remove my "portable" Works license and use the Runtime license I purchased for the application. Once the system is properly backed up, I can remotely modify the application if necessary. This way, I have a choice of where I edit the application.

  10. Posted

    See the Downloads section for Mitsubishi. I added the current manual (IB(NA) 66171-E) as well as an older version that was scanned by Mitsu and stored on their website (UMAD[1]). Best of luck.

  14. Posted

    Paul: The thing to know is that the drive frequency determines the speed of your motor. When you set up a vector drive, one of the setup parameters is the nameplate frequency at base speed. (Base speed for motors made in North America is 60Hz). All of the drive's calculations are based on that relationship to the base speed. So, it does not matter to the drive what units you send as a reference speed, it will compare your speed reference in Hz to the motor base speed to what it is actually reading from the encoder. It will then control the output of the drive (voltage, amps and hertz) to change the motor speed. When I have done this in the past, I simply have a calculation in the plc that converts my user units (feet per minute, rpm, etc) to frequency in hertz. I then send that number (usually multiplied by 10) to the reference speed memory location in the drive. I hope this clarifies things for you.

  15. Posted

    Paul: Today's variable freq. drives have stable speed regulation. By adding the encoder to the system and using closed loop vector control, the speed regulation not only gets better, but the drive can make the motor respond to changes in load. Today's drives, when operated either in open loop vector control (without encloder) or closed loop vector control (with encoder) can sense load changes and change the waveform going to the motor. Open loop (or V/Hz mode) will not regulate the speed as well and will not always detect changes in speed due to the load. I hope this helps.

  16. Posted · Edited by drforsythe

    The potentiometers control the value of two special memory bytes. The values in these memory locations could then be used to create adjustable timers, speed command setpoints, etc. Sorry, but I do not have a manual to tell which bytes the pots control. Here is a link to the manuals on the Siemens site: http://www.sea.siemens.com/us/Products/Automation/Micro-Automation/support/Manuals/Pages/S7-200Manuals.aspx

  17. Posted

    "So think about the green programmers and techs you've ran into. What does everyone lack that keeps them from succeeding?" The biggest thing I learned from green techs is that we as controls engineers, need to pay attention to our customer(s). Whether our customer is someone who directly pays for our services, or the person running, supporting, selling or purchasing the machine, the customer needs to be listened to. I have seen many new techs come and go (usually into sales) and the biggest thing they lack is humility. Without humility, we do not listen. Without listening, how can we possibly find out what our customers really want? It usually takes a while for a new tech to realize that they are not as good as they think they are. So, the long and short of my response is: Teach your students that they have two ears and one mouth and to use them in that proportion. To be successful, listen to the customer. Don't be too cocky and deliver what you say you are going to deliver. Chances are that you may be able to program a plc better than them, or design a control system better than them, but they almost assuredly know their machines or processes better than you.

  20. Posted

    I have never used it, but I was curious, so I searched. Here is a link I found. There is a contact link at the bottom of the page. Best of luck. http://www.brixia.com/microset/mars.html

  21. Posted

    The MR-J2 servo manuals are here: http://www.meau.com/eprise/main/sites/public/Downloads/-search_results?SType=3&DocType=010&SessionNum=&UserID=&Division=00015&Opt1=Yes&submit1=Search&Family=0001520015&Series=000152001520085&Line=00015200152008520490&ManualType= If that link does not work, you can go to www.meau.com , select Downloads, then Manuals, then use the search dialog for the product you are looking for.

  22. Posted

    In my experience, I have not used isolation tranformers on drive applications. I have, however, used line reactors on the incoming supply to the drive. We have line fluctuations at my location that are smoothed by the line reactors. The drives are able to accept "normal" levels of line fluctuation, but if your plant voltage is on the higher end of the acceptable range, it does not take much of a spike to cause and overvoltage fault on the drive. One of the causes of incoming line fluctuations is when the power company (or your plant) switches the power correction capacitors in and out of service. We had one machine that would fault every morning at approximately 10:30 am like clockwork. The drives (PF70) would display overvoltage faults. Our bus voltage had a nominal of 490 volts, which is within the tolerance of the drive, but the caps switching caused spikes. The problems were eliminated through the use of a line reactor on the input side of each drive.

  23. Posted

    The main thing to remember is that in this field, there is much to learn. Even seasoned veterans can be stumped by something - not because they are not smart, but because they might not have been exposed to something before. This field provides ample opportunity for those who are willing to learn and aren't afraid to ask questions. This forum is a great place to learn technique, so you have started in the right direction. Don't EVER be afraid to ask questions. I would rather work with someone who is willing to ask questions and learn the right way, than waste my time with someone who thinks he knows it all and ends up wasting time, money or worse. Best of luck in your endeavors.

  24. Posted

    I use PF40 drives with the ethernet module in our operations. I have also used the PF70 drive with 'Safe Off' feature. I have stopped cycling power to our VFD and servo drives during a safety circuit interuption. The circuits I set up utilize a safety relay with both immediate outputs as well as time-delayed outputs. When the interuption occurs, the immediate output from the safety relay will issue a stop command. This allows the drive to try to stop the load as quickly as possible. Then, after the time delay (usually 1/4 to 1/2 second) one set of time-delayed contacts will remove the "enable" signal to the drive and a second set of contacts will remove power to a contactor (safety-rated and monitored motor starter). The safety-rated motor starter is connected between the drive and the motor. It is important that you set the deceleration time of the drive to a value LESS than the time-delayed contacts in your safety system. If you break the connection between the drive and motor while the drive is powering the motor, you will damage the IGBTs on the output of the drive. This may not happen the first time, but over time your drive will prematurely fail. The above setup will increase the uptime of your machine because you will not have to wait for communication to resume. Also, it is safer because your motor will be physically disconnected from the drive (regardless of the charge state of the drive's capacitors). This method is recommended by most drive manufacturers to prevent premature failure of the input power circuit. A-B's website has examples of wiring on their website. Hope this helps.

  25. Posted

    After seeing the new Kinetix product, I too was suspicious of it being a Lenze product. When I asked the guys from Rockwell specifically about Lenze, they admitted it was a 'joint venture'. They assured me that Rockwell drove the spec and it was much more reliable than previous Lenze products I have used. Of course, they are going to say that. As far as the motion goes, IF you were able to change PLC platforms, I would seriously consider a CompactLogix with the SERCOS card. I have done several apps with ControlLogix and they have worked well and were not too bad to integrate.