Best way of totalizing flow?

[rootboy]

Yeah, I know this thread is 8 months old, but I gotta comment.

A pulse from HART? Really?

Sure! Some at 1200hz, the rest at 2200hz... ;>

 

[NoName]

If you can set your meter up to output a pulse rather than rate then you won't have a rounding issue. Use the rate of change that the pulses are coming in at to derive flowrate.

Reading the instantaneous analog value will create errors.

No unfortunatley we can't set up the meter to output pulses. This is why we are trying to generate pulses with the PLC (S7-1200). I use the system clock of 10Hz to calculate the avarage value within 1 sec. So that the value is as close as possible. The flow rate is mostly steady and does not change that much.

I was thinking that if I were to use a faster clock, then the error would be less, no?

 

[rootboy]

No unfortunatley we can't set up the meter to output pulses. This is why we are trying to generate pulses with the PLC (S7-1200). I use the system clock of 10Hz to calculate the avarage value within 1 sec. So that the value is as close as possible. The flow rate is mostly steady and does not change that much.

I was thinking that if I were to use a faster clock, then the error would be less, no?

That's unfortunate. Yeah, looks like you are going to be doing the "area under the curve" calculation. So the faster, the better I suppose.

You are probably going to bang up against some limitations of the PLC that will make speeding things up past a certain point harmful/unproductive, so don't go crazy...

What is the make and model of your probe?