Weight Application - Terminolgy and Programming advice

MorphuisOGrady · Jun 2, 2015

Hi there,

I have an application that I am struggling to find the correct terminology for.

From SCADA, the operator should have the ability to fill by time or by weight. If by time the pump will run for a fixed time.

If by weight I want to check that the weight has not changed by x kg in y seconds that the machine must be full so I can transition on to next step in sequence.

What is this called? Derivative perhaps? What would you call the parameters so an operator could understand easily what is happening.

keithkyll · Jun 2, 2015

Rate of Change. If Rate of Change = 0, then next step.

MorphuisOGrady · Jun 2, 2015

keithkyll said:
Rate of Change. If Rate of Change = 0, then next step.

Thanks Keith. So for my 2 parameters on my HMI screen:

X: If weight increases greater than this much the machine is not full
Y: Check weight increase in this time

How would you name these variables?

Depending on the material being feed to machine the weight increase varies considerably over time.

Typically is there a built in instruction for "Rate of Change" in a PLC? I'm using Logix5000 controller and can only think of the DERV instruction but I don't think that will do what I need.

Is it just as simple as a taking a sample every Y seconds and comparing it against previous and if weight hasn't increased by X then advance the sequencer.

PirateControls · Jun 2, 2015

X: bool, MachineFull
Y: real, WeightAdded or CurrntW8Chng

Some of this really is a matter of personal preference.

MorphuisOGrady · Jun 2, 2015

PirateControls said:
X: bool, MachineFull
Y: real, WeightAdded or CurrntW8Chng

Some of this really is a matter of personal preference.

This won't work. I need a parameter to allow operator specify how often the weight should be checked.

Bit_Bucket_07 · Jun 2, 2015

MorphuisOGrady said:
Thanks Keith. So for my 2 parameters on my HMI screen:

X: If weight increases greater than this much the machine is not full
Y: Check weight increase in this time

How would you name these variables?

Depending on the material being feed to machine the weight increase varies considerably over time.

Typically is there a built in instruction for "Rate of Change" in a PLC? I'm using Logix5000 controller and can only think of the DERV instruction but I don't think that will do what I need.

Is it just as simple as a taking a sample every Y seconds and comparing it against previous and if weight hasn't increased by X then advance the sequencer.

Are you simply looking for appropriate terminology for describing these variables to the operator via your HMI? If so, then how about:

X - Weight Differential
Y - Sample Interval

Weight Application - Terminolgy and Programming advice

MorphuisOGrady

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keithkyll

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MorphuisOGrady

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PirateControls

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MorphuisOGrady

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Bit_Bucket_07

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