Hello,

I have a liquid flow sensor with pulse output. Let's say it has 100 pulses / liter

I connected it to I5.

I would like to read out the flow value every minute and display it (freeze it for the next minute and then repeat this every minute).

If the flow value is too low (lower then 10 liter/min), the alarm marker should be set.

I think the value from counter should be copied to VM space, but I don't know how to display it every minute and how to set the alarm.

Any idea?

There is a better way to read the flow rate, see attachment. For 10 l/min you have 1000 pulses/min = 16,67 pulses/s, therefore 16Hz in simulation is too low, 17Hz in simulation is okay.

Regards, Scorp

Great Scorp, it seems that this  program of yours is excatly what I need. Thank you very much.

ixo65

How fast are the impulses?

The program, which you attached, is it from you or do you have that from the Forum?

I don`t know excatly how fast they are.  First, I have to measure it, to be sure, since it is low cost type. The plan is to connect it to water tap and count the number of pulses for 100Litres or so... Then I wil know excatly how many pulses for 1 liter it has.

Can I count those pulses with ordinary Count up/down counter from logo? It should be OK, right?

Sensor is this one: (click)

From the description, the formula should be:

F=[5Q-3]±10%, F means instantaneous pulse value(Hz), Q means instant flow(L/min)

So, if the requested flow is around 20l/min the frequency should be around 100Hz. No problem for I5 of Logo, I think.

Then use it as you need. You also can change the time parameter of the threshold trigger to .e.g. 1,2s, then the threshold parameter must be changed to 20. With small time parameter you get an earlier reaction, but the threshold parameter also get small. You have to play with both parameters to get the best result. The calculation for the threshold parameter depending on the time parameter is not so difficult. The on-delay behind the threshold trigger must be proper to your application.

Regards, Scorp