Watter flow meter Pulse counter and relay wireless with nodered

Hello, I need to connect:

  • 1 Liquid Flow Meter and 1 relay and transmit the pulse information over the air 0.6 mile. Also I need send back relay activation.

I need to have one base station and 9 remote stations.

I need to control from nodered.

Can anybody recommend the products pls.

Picture of flow metter:


Could you provide a link to the Datasheet for the sensor. I want to see what type of output it provides. If it’s just a high/low signal once per rotation then that could be accomplished using our Enterprise Push Notification board, but if it outputs a PWM signal that would require a different product. I presume it’s just a high/low once per rotation but would like to know for sure. Relay outputs at the 9 remote locations should be no problem.

Any idea of the frequency of contacts coming out of the sensor?

Hello. Here is the information. But yes high/low signal 33 pulses per liter.
I think maximum is 275 pulses per second.
The idea is have both relay and pulse reader in same station.

Flow rate : 100-30000(m3/h)
Flow Pulse: F(Hz)=(0.55xQ) ± 3% Q=L/min
1 L water ~=33 Pulse
Max. Working Current : 15mA (DC5 V)
Min. Working Voltage: DC 4.5V
Working Voltage:DC 5V~18V
Load Capacity: =10 mA (DC 5 V)
Insulation Resistance: > 100M OHM
Accuracy :+/- 5% at (50~500L/min)
Cable Conection: Red: Positive+ (IN);Black: Negative- (GND);Yellow: NPN Pulse signal (OUT)

I’ve used these cheap flow meters and determined it’s better to track the flow verses flow rate, since each pulse is triggered by a given quantity of water. The local MCU would essentially measure a Totalized Flow, then it (or your Gateway) would calculate Flow-rates over any chosen time period.

You can get fairly accurate results if you calibrate the water-per-pulse at the operating pressure that the meter will experience. That can be as simple as a bucket test. They also work at 3.3V.

Do you have Power available at all locations? If not, is Solar Recharge an option?

@Travis, It looks like I use INPUT_PULLDOWN with a RISING Interrupt for most of these meters, but some require the opposite. But I haven’t seen a PWM flow meter in these cheap Chinese sensors.
I’m thinking (9) Photon Relay Boards w/ XBee’s, with (1) PR52-11 Gateway (or similar)?


Yes I will need solar energy.
I was think buy that part local.
But maybe there is ncd product for solar energy?

Hello @Travis . Any update on this ?
I need to make the order to start with ncd.



To be honest @rfontaine has much more experience with these devices than I and I trust his opinion. What he is suggesting sounds correct to me. That would give you a relay as well has GPIOs for monitoring the sensor. That said what he is suggesting is a Photon relay board which will require a bit of programming. Do you have any experience with C/C++ application development? If so I would absolutely go with what Ryan suggested. If not let me know and we can discuss possible alternatives.

At this time we do not offer solar power accessories but it is certainly something we are looking into. Once again Ryan will have some fantastic recommendations for this as he has implemented it himself. Keep in mind @rfontaine is not an NCD employee but rather one of our most valued customers. He is a great guy and always willing to help out other users. Just saying that so you don’t hold him to Employee support standards.

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Thanks Travis. The more I think about it, this will actually get quite complicated using Photons.

It may be easier to read the Flow Meter Output directly with an XBee (I/O sampling change detect) and aggregate the readings from all 9 XBees at an internet connected gateway (Cellular or WiFi).
Then have each XBee drive it’s relay (change a Pin High/Low) using an API command from the Gateway.
All 9 Flow Meter Xbee’s would be configured the same in XCTU, and you only maintain/modify your logic on the one Photon/Electron/Boron Gateway.

@Travis, do you have a relay board w/ XBee socket? I believe that was/is a major part of NCD, I’m not sure?

@dserrano, what Load will the Relay Drive, and @ what Voltage?
Your power budget (battery+Solar) will need to account for the Flow Meter, XBee, Relay Load, etc.

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@rfontaine thanks you very much for help. The load of the relay is 100ma 24 volts. Is a selenoid.

I was think make this with pycom with lora. What do you think about ?

About solar power. I was think use a 20W x 24V panel with charge regulator and 2 battery of 5 amps.
Also I have to use some power supply to down the voltage from 24 volts to ncd voltage support.

All this have a cost of 95 dollars in my country.
Do you have a better idea?

I’ll let @rfontaine comment on your solar power power components but they seem perfectly reasonable to me.

As for Ryan’s questions for the relay/input board controllable/monitor-able over XBee yes we have solutions for that like this:

That board has inputs for monitoring 0-5VDC or dry contact closure signals and a relay output. It can be ordered with different wireless XBee modules. One caveat though is you have to send a command to the board to read the input meaning it will not just send a transmission if the input opens or closes so you would need to poll the status of the input so that would complicate things a bit I believe.

If you could write the code to run on a PyCom Lora module and handle the wireless transmissions then I see that as a good alternative as well.

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@Travis What module for lora pycom with relay and inputs can you recommend?

@Travis Hello. Any update on this ?


I apologize for the delayed response. We’ve been working on a project that had to get out the door today.

We have this adapter for LoPy modules that allow the LoPy modules to plug into the IoT sockets on our boards:

Here are some IoT socket relay boards it would be compatible with:


Have nice day

We want to add 3 analog voltage sensors.
I can not find anything with analog inputs and the IoT interface.

How can I connect:
WinPy + 1 relay + 2 digital inputs + 3 or 4 analog inputs?

Thank you!

PyCom or iot interfase to I2C it could also be used

I’d recommend the following if the relay required is less than 10 amps:

That I2C ADC mini module just plugs into the I2C port on the 1 channel relay board. The 1 channel relay board also has 7 GPIO lines. Should be everything you need.

Great Thanks!

Have nice day

@Travis I am ready to make my first order but I need to know if Pycom WiPy2 & LoPy IoT Interface Adapter are compatbile with WiPy 3.0

I ask yesterday here:

Is important because WiPy2 have an issue with the interruptions ISR and I will use this capability.

Yes, WiPy2 adapter is compatible with WiPy3.

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