Hooking up a water meter to analog input

[trevorhays]

I purchased a Dwyer Series WMT2 Multi-Jet Water Meter with Pulsed Output and I would like to capture the water used by each zone.

I am unsure how to attach the water meter which has 2 wires to the analog to digital converter on the sprinkler pi. Which wire attaches to the input, vcc and ground. I have attached the spec from the water meter to show you what I’m working with.

Thank you for your help.

Attachments:

1. watermeter.pdf

[Ray]

I actually purchased the same water meter a while back. These types of water meters have reed switch inside and it doesn’t output an analog signal directly. Instead, you need to use a digital pin (ideally interrupt pin) to count the number of clicks within a unit amount of time, and that’s proportional to the flow rate. We are working on adding support for this type of water meters in the next firmware. The current plan is to make use of the rain sensor port, so you can connect a water meter to the rain sensor port, and the software will allow you to choose between using that port as a rain sensor or flow sensor.

[d-dawg]

I have a Hall Sensor type flow meter which includes a transmitter. So the output from the meter is a 4-20mA signal. I’m wondering if there is an available A/I on the OS that can read this analog signal.

Apologies in advanced if the topic has been covered in other posts but I wasn’t able to find a thread that dealt with this topic directly.

[BinaryOS]

4-20mA signals are standard for industrial applications. I believe you will need to read voltage so you will need a resister across the output sized to give you the required voltage drop across the resistor. If you used 250ohms it would give you a 1v to 5v signal.

I just ordered an Arduino pro mini, plan on connecting to my flow meter to read the pulses and report back to a raspberry pi that will log water flows for each zone, graph etc etc.. or Ray will beat me and add flow to open sprinkler.
The flow meter I have is:
http://www.nymet.com.au/valves/1flowsensor.html
was quite cheap on ebay! 🙂 🙂 🙂

[d-dawg]

I understand that the current signal can be converted to voltage signal. I guess the question I was driving at was the availability and identity available analog inputs on the OS board that could be used for measuring flow.

This post suggests that this should be possible but I haven found any further discussion on this and it isn’t clear (to me) of the location of the A/I connections
http://rayshobby.net/opensprinkler/svc-faq/

I understand Ray is implementing a solution for flow measurement using the rain sensor. However if one has a flow meter (as I do) that provides a flow signal already conditioned to an analog signal then the rain senescence input wouldn’t have to be sacrificed for this purpose.

[Ray]

There are several analog pins available on OS board. For example, on OpenSprinkler 2.3 (AC), the available ones are A05, A06 and A07. The pins are all located at the top edge of the PCB. When referencing the pins in the source code, you can directly use the pin index (e.g. analogRead(5)) or use macro defined pin name (analogRead(A5)). Because the microcontroller runs at 3.3V VCC, the analog pins accept any signal between 0 to 3.3V.

[Author]

Posts