Totalise an instantaneous Flow rate

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i need to Totalise an instantaneous Flow rate in scada.
i will probably use the scada totalise function, just want to know if this code concept is correct for learning purposes

here is my concept , does this seem practical

Flowtag - Flow instrumentation will typically output a value around the 10.0kg per minute set-point under a closed loop system

Start Value - a register to hold captured instantaneous value
End Value - a register to hold captured instantaneous value
Avg Value - a register to hold averaged value over 1 Minute

Total Flow - a register to hold totalised value

the scada code below will be set-up as a continuous task which will run every 1 minute


  1. Avg Value = (Start Value + End Value) divide by 2
  2. Total Flow = Total Flow + Avg Value
  3. Start Value = Flowtag (capture value to register)
  4. pause 30 seconds then continue
  5. End Value = Flowtag (capture value to register)
  6. pause 30 seconds then continue
  7. loop to step 1
first scan will not be correct but otherwise ?
 
Last edited:
Your accuracy will depend on the how exact your 1 minute measurement is.
I belief you have an error. You are capturing a 30 second average, but counting it as 1 minutes worth. In step 2 you need to multiply Avg Value by 2.
 
i need to Totalise an instantaneous Flow rate in scada.
i will probably use the scada totalise function, just want to know if this code concept is correct for learning purposes

here is my concept , does this seem practical

Flowtag - Flow instrumentation will typically output a value around the 10.0kg per minute set-point under a closed loop system

Start Value - a register to hold captured instantaneous value
End Value - a register to hold captured instantaneous value
Avg Value - a register to hold averaged value over 1 Minute

Total Flow - a register to hold totalised value

the scada code below will be set-up as a continuous task which will run every 1 minute


  1. Avg Value = (Start Value + End Value) divide by 2
  2. Total Flow = Total Flow + Avg Value
  3. Start Value = Flowtag (capture value to register)
  4. pause 30 seconds then continue
  5. End Value = Flowtag (capture value to register)
  6. pause 30 seconds then continue
  7. loop to step 1
first scan will not be correct but otherwise ?

What is your Flowtag?
If this is a Flow rate your code will not work.
If this is an accumulated what value does it roll over back to zero?

Typically if this was a flow rate ie 10kg/Min
Create an event ie Devx_Accumulate.
The trigger will be when Devx is running.
Set period for accuracy required ie 2 seconds
Action will be your Devx_accumulate_function()

Code:
Function
Devx_accumulate_function()

    Devx_Kgs = Devx_Kgs + (Flowtag / 30);

END//
 

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