Moving avg values from cyclical pumps

[drbitboy]

... But due to the way the copy instruction works it's necessary to copy to a buffer, then back.

Depends on the COPy implementation, but by copying "down*", a buffer is usually not required.

* e.g. in Logix mnemonics: [COP array[1] array[0] 7]
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[drbitboy]

Another question: What's the simplest totalizer I can build with ladder logic?

I think I have already provided that, but if you don't have AVE or MAVE:

• Tags
  • REAL flow: continuously updated flow measurement
  • REAL peak: current cycle's peak flow.
  • REAL tot: running total
  • REAL arr[8]: 8 element array, arr[0] to arr[7]
  • BOOL pump_is_on: pump is running on this scan
  • BOOL pump_was_on: pump was running on previous scan
• Code
  • XIC first_pass ### Initialization
    • CLR peak
    • CLR tot
    • FLL arr[0] 8 ### or ... 9; see below
    • OTU pump_was_on ### or OTL, so this instruction is probably superfluous
  • XIO pump_is_on XIC pump_was_on GRT peak 0 ### Falling edge of pump running if peak is positive
    
    • SUB tot arr[0] tot
    • ADD tot peak tot
    • COP arr[1] arr[0] 7 ### or ... 8; see below
    • MOV peak arr[7]
  • XIC pump_is_on ### Pump is running
    • XIO pump_was_on ### Rising edge of pump running
      • CLR peak
    • GRT flow peak MOV flow peak
    • OTE pump_was_on

If arr is REAL array with 9 elements, peak is arr[8], the Length of 8 in the FLL is replaced by 8, and the Length of 7 in the COP is replaced by 8, then the red instructions are not needed.

Caveats

• The totalizer will represent fewer than eight peaks for the first 7 cycles, so the tot by 8 will be give a misleading value for the first hour.
• With fractional REAL values, there will be some rounding error in the totalizer.

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[drbitboy]

 

[drbitboy]

Whoops!

Fixed a typo.

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[drbitboy]

Simplified that last rung a bit:

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