Re: A bit of a math problem

number of pumps = ((discharge rate) /(individual pump capacity))+1

if the rate of change of tank level is not linear with discharge rate then use a lookup table

Re: A bit of a math problem

Thanks Richard.

My problem is to find that rate of change.

I have a sensor that gives me the level of the tank. Also a variable 'rate' that is set by the user.

Now I have to combine these two and decide how many pumps should work at a time.

Ioannis

Re: A bit of a math problem

Take measurement ever XYZ sec.

Discharge rate is First-Second.

Eg do something like this:

Code:

`RunFirstTime:`

ADCIN SensorValue' or whatever

OldSensorValue=SensorValue' initialization at beginning of program

return

SubRoutineToRunEveryXYZsec:

ADCIN SensorValue' or whatever

DischargeRate=OldSensorValue-SensorValue

OldSensorValue=SensorValue

RETURN

Depending on how often you call SubRoutineToRunEveryXYZsec you can get quicker response, or better resolution(wider range of values). That all depends how quick your process is.

Re: A bit of a math problem

Thanks Richard. I see what you mean.

Greet help on that small hour that my mind is almost in literary sleep mode!

Ioannis

Re: A bit of a math problem

Another approach would be:

SELECT CASE Level

CASE < 80 : HIGH Pump1 : LOW Pump2 : LOW Pump3 : LOW Pump4

CASE < 70 : HIGH Pump1 : HIGH Pump2 : LOW Pump3 : LOW Pump4

CASE < 60 : HIGH Pump1 : HIGH Pump2 : HIGH Pump3 : LOW Pump4

CASE ELSE : HIGH Pump1 : HIGH Pump2 : HIGH Pump3 : HIGH Pump4

END SELECT

Re: A bit of a math problem

Thanks mpgmike. Good one too!

Ioannis