drforsythe

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Posts posted by drforsythe

  1. Posted

    We use Micro Motion flow meters throughout our plant.  They are great meters.  We have had issues with the old (>20 years old) devices after power failures.  I don't recall which model the old ones are, but we cannot even get them repaired reliably.  We have been systematically replacing the old units with the 5700 series transmitters.  They work with some of the old flow sensors, depending on the number of wires in the sensor.  I highly recommend contacting Emerson to find out who your local Micro Motion salesperson is.  They are really good to work with (at least in my experience).

    1 person likes this

  2. Posted

    Unloaded motors are difficult to tune and will sometimes exhibit the problems you describe.  If I were you, I would try one of the following:

    Find a load for the motor.  It could be a plain gearbox with no load, or a pulley system.  It is best if you can create a geared ratio of at least 3:1.  The higher the ratio, the better results you will find when doing the autotune.

    If you can't find a load, then try to change the autotune parameters relating to the motion.  I am not near the software, so I can't tell you specifically what to change.  Start with the distance then change speed.  I have a feeling once you open up these settings, you may see a failure in the autotune.  Again, unloaded motors are hard to tune and that may show up if you try it with a longer move or higher speed.

  3. Posted

    When you say that the hookup test ran flawlessly ("The motor will slowly turn... for as many revolutions as I input.")  Are you using the same speed settings (accel, velocity and decel) settings when you run your test as the hookup test uses?  I have had similar experiences during my testing where I have had aggressive accel or decel rates or the speed was excessive.  

    How long after motion starts do you receive the error?

    Do you have any gearing between the motor and the load?  Is the inertia of the load within the motor specifications?  If inertia is not matched between load and motor, then you will be able to achieve slow velocity movements but will most likely fail when positioning.

     

  6. Posted

    We have been using Strongarm enclosures in places where we need to suspend them from a wall or pole.  They offer painted and stainless steel enclosures. They have several options available.  the website is www.strongarm.com.  Good luck.

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  7. Posted

    I find myself getting frustrated with vague or overly-simplified requests for help, as well.  Sometimes I think that it would be awesome to have a forum with a form to fill out that asks for pertinent details, then makes those details searchable and filtered by manufacturer, model, symptoms or scope.  I am sure there are some knowledgebase and web-based support forums for products that are like that.  Then I realize the following:

    1)  It takes time and effort to create a support forum like that.

    2)  If that support forum were created, we would all find things that would be nice to have for it.  Once we added our 'two cents' to the list, the wants list would become too large and searches would either return way too much info or not enough.

    3) Those that do provide pertinent information when asking for help will find the required information for the forum to be a juvenile requirement and then probably not use the forum anymore.  This would lead to a reduction of requests and more importantly, a reduction of responses because of the extra time it may take.

    4)  Then, the most important one - freewill plus the GIGO principle.  If someone does not provide adequate information (Garbage In) or is simply looking to get their homework done by someone else, we all have the free will to choose not to respond to the request (Garbage In = Garbage Out).  OR, if we have time to help,  we could simply post back the info we need in order to help.

  8. Posted

    I FINALLY got tired of untangling all of the programming cables I need to use and started bagging them in heavy duty ziploc bags.  I have several bags in my toolbox and their contents are segregated by function (or even frequency of use for some of the oddballs).  I write the name of the technology or type of cable set on each bag and that makes it a lot easier to locate the cables when I need them.  It also keeps them from tangling. I work in a manufacturing facility now, so I keep all cables in a roll around toolbox/workstation.  This would have been helpful when I was on the road and used a roll around case like a doctor's bag.  The same would work for a backpack.

    Need to carry:

    screwdrivers, cables, wire strippers, small flashlight, thumb drive, change for the vending machine, phone charging cord and battery pack.  The list could get long...

  10. Posted

    Good call, Joe.  That is common especially in plants with unstable or uneven flooring.  In our plant, a forklift driving by can shift the concrete slabs when it drives over them.  Way back when the building was erected, the contractor was pressured to rush on the concrete installation.  The quick-cure and poor base prep caused some slabs to curl on the corners causing a slight "dishing" in the center of the slabs.  We have to shim the enclosures in some areas to keep them level.  

  11. Posted

    Does it look like the enclosure was dropped?  How were the holes cut in it (manually using hand tools or boring mill, radial drill, etc.)?  If it was dropped, the hinge or area where the hinge is welded could be damaged.  If someone cut the enclosure on a boring mill, for example, the tool could have crashed the door causing distortion.  Another place it could have been damaged is the fold around the doors.  If they are distorted, they will rub on the door opening.  Regardless, you will need to inspect for the location of the damage and then "help it back into position".  A large enclosure like that typically takes a lot to distort it.  It will take an equal force to move it back.  I have had to use a large mallet in the past to move a door back that was hit by a forklift.  Good luck.

  12. Posted

    That usually means that the card can take multiple types of analog inputs.  For example, it could take +/- 10VDC, 0-10VDC, 0-20mA, 4-20mA, thermocouple (multiple styles) or RTD.  The card would usually have some hardware configuration (different terminals to select the type of input) and software configuration for scaling.

  14. Posted

    I spent some time this morning looking at your program, but I cannot easily determine the mapping of the network devices to the internal memory devices of the PLC.  It would take some time to study the prints, the physical layout of the machine and the program in order to determine the network map.  That is something I could not do in the time I spent this morning.  I would recommend contacting the original machine builder or contact a Mitsubishi office and ask for someone who is familiar with the A series PLC.  I worked on stuff like this over 20 years ago.  The product has long ago been replaced by new PLCs, networks and software to program it all.  I am sorry I cannot help you.  Best of luck in your search.

     

  16. Posted

    Hello.  This topic is not controls-related, but I think I could learn something from the group. 

    In addition to being an electrical controls engineer, I am a medical first responder for the plant I work in.  It has been suggested that all first responders be easily identifiable by the plant and office staff in case of an emergency.  This request could easily get out of hand- nobody wants to wear a bright green t-shirt to work every day or a hard hat with strobe and light.  My question is this:  Do the first aid response personnel in your places of employment wear or carry anything that helps to identify their role?  If so, please share your experiences and images if you have any.  Silly or comical images are definitely accepted, as they may help to demonstrate what we DON'T want to do.  Thank you and stay healthy and safe!

  17. Posted

    6 minutes ago, mouhab_ah said:

    I will try to find and told you the news.

    But in the diagram that i upload in the  first post there is address in the top of each remote i/o module , is that enough ?

     

    That is a good start, but it doesn't state which device(s) are used in the address ranges.  For instance, Melsecnet/mini can be tagged to X, Y, M, D... devices.  Your program should help us determine what devices were used.

     

  18. Posted

    I used to work for a company that sold Mitsubishi 20+ years ago and would have to regularly talk my customers through the setup of their Melsecnet networks.  They would upload a program using Medoc from a PLC that was configured with a GPP unit.  The GPP had tables to fill out for the network settings, but Medoc did not.  When they would download back to the PLC CPU, the network settings would be missing.

    All that being said, the biggest challenge was knowing what memory areas to read from and write to when setting up the mapping the physical inputs and outputs.  Some customers had well-documented prints that showed the real-world I/O and how it related to the virtual I/O.  Others were not so easy, and we would need to study their code for clues.  Do you have any such info?  Do your electrical prints have the information?  Or is your program documented to show which memory locations were used?

     

  19. Posted

    I am not familiar with your controller, but I would use an averaging, or filter command to reduce the fluctuations.  How much is the 0-10V signal changing?  Looking at your graph, the values on the Y-axis are only changing from a min of 73.07 to a max of 74.2.  That is a difference of 1.13.  That is if I read the scaling correctly.  I am not sure what units the X-Axis units are or how those values correspond to a 0-10V signal.

  24. Posted

    I always leave feedback.  Most of the time it is positive.  I also leave written feedback whenever given the opportunity.  It allows me to express exactly what I liked and what was good but could use a little more attention.  The simple "Strongly Agree" to "Strongly Disagree" selections don't give opportunity for details.  My company pays a lot of money for the service, so I leave the feedback so they can become better.