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JohnR

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About JohnR

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  1. Anthropomorphizing PLCs

    Well, I use to comment my code in the first person; "In this net "I" store the raw encoder count from MI 1 to MI 12, then "I" scale it for use on the display....." But, over the years I've come to commenting in the third person; "In this net "We" store the raw encoder count from MI 1 to MI 12, then "We" scale it for use on the display....." It make the PLC feel like he is really part of the process......
  2. Shielding/Screening

    Screen/Shield, always been the same thing in my mind, although from a broader perspective, shielding may refer to the braid/foil/drain wire on a cable, while screening may be thought of as something in a bigger sense, like a metal (screen) partition between noisy parts of a panel and noise sensitive parts..... I've been doing industrial control for 30 years, and was always lead to believe "one end" grounding to be proper in this field. But, before that, I worked in the audio electronics field, and the proper method was to ground both ends of the shield, but you also did your best to maintain a "star ground" topology to eliminate potential ground loops..... just my 2cents..... Disclaimer.... at least in my part of the world, I realize Aus and others have words and meanings that us funny tawkers don't get........ JohnR
  3. Hi Cam, Good call....... Silly old me, I have a RHR to get the fault code from the VFD right below MI 13, and the vector length was set to 16..... DUH....... JohnR
  4. Hey All, Just ran across a quirky little thing while working on a new project, I'm wondering if anyone else has experienced this..... I'm doing MODBUS control of an AB Powerflex VFD , and mind you this is not my first experience doing this, I've done several projects using V570's, and usually do not run into problems. This time I'm building some controls around a V120, and I am having an issue reading the speed feedback (frequency) from the VFD. I've compared my logic to a previous project (logic looks the same, only difference is the MI's used in the RHR FB), and even set up two PLC's on my workbench (V570 & V120), and hooked up each to the same VFD to test. Problem I have is that when the net is true, I get the correct reading, but when the net is not true I get some other number in MI 13. I have searched MI 13 and it shows it only being used in the RHR FB and on the display. I have slowed down my index to 1 Sec per step so I can see it in debug, and find that if I unplug my MODBUS cable while The net is true, then MI 13 stays put even after the net goes false, so it doesn't seem that the funny number is being driven by something in the program. V570 reading speed feedback of 60Hz V120 reading speed feedback of 30Hz when the index equals in that net V120 reading something else when the index does not equal in that net I'm starting to wonder if it has something to do with Enhanced Vision vs. Standard Vision? Any thoughts? Regards, JohnR
  5. JohnR

    images for forum
  6. MI13 search.PNG

    From the album JohnR

  7. 570 modbus.PNG

    From the album JohnR

  8. 120 modbus not equal.PNG

    From the album JohnR

  9. 120 modbus equal.PNG

    From the album JohnR

  10. JohnR

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  11. 570 modbus.PNG

    From the album JohnR

  12. 120 modbus not equal.PNG

    From the album JohnR

  13. 120 modbus equal.PNG

    From the album JohnR

  14. MI13 search.PNG

    From the album JohnR

  15. That's interesting Joe, I never paid attention to SB13, I've always just used a Positive Transition Contact with SB3 when I roll my own timers.... Also, did you do this on the new "wide screen" version? it opens on my older version, but net 3 is clipped off. Something I guess we gotta watch out for as we transition into the wide screen format.... JohnR
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