fEsTiDiOuS

MrPLC Member
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About fEsTiDiOuS

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    Hi, I am New!

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  1. CPT instructions on a PLC-5/40

    I'm working to fix/improve the functioning of a program running on an a PLC5/40E.  I think high Scan Times are a big problem with this current program.  ((Backstory:  someone added some quasi motion control, and it sort of worked for a while.  Now that it's broken, the operators of this machine want it back. ))  I'll keep my question simple, PLC5's are new to me: There are 36 rungs with CPT instructions as the sole output, a third of these instruction are executed every scan.  I'm going to replace them with MOV instructions. My question is, is there any sneaky PLC5 reason to do a CPT instead of a MOV?  Is there a better way to do this? The CPT instructions that execute move integer values to a data file used by the HMI to control the coloration of touchscreen buttons.   Thank you for your time. PS: I'm new-ish to this forum, please feel free to let me know if my question was asked correctly or not.
  2. GSV Instruction

    I suggest using GSV's sparingly, they really slow your program down. I don't know how much accuracy you need.  If you make a logic clock with a timer and counters that is corrected once a day with a GSV your program will run a lot faster than if you execute a GSV every cycle. 
  3. ControlLogix

    Amanda I think they are trying to tell you is that the PLC is big-endian,  and the micromotion is little-endian.  It's something that is corrected/converted mostly automatically, but not here.  The wikipedia article on 'endianness' is pretty good: https://en.m.wikipedia.org/wiki/Endianness   Unfortunately in your specific case the problem is being made more confusing by the complicated way in which REAL numbers (that is numbers with a decimal point) are stored. I'm new at this.  Are ControllLogix PLC's big-endian? Eddie your answer is amazing. I couldn't use your link though.  Here is a shortened link to the same place: https://goo.gl/Jmt9D2 I found this piece that very nicely explains IEEE 754:  http://www.oxfordmathcenter.com/drupal7/node/43