# Raspberry pi and Node-RED kwh meter pulse counting?
**URL:** https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789
**Category:** Hardware
**Created:** [16 August 2021 12:58 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789 "2021-08-16T12:58:34Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [16 August 2021 12:58 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/1 "2021-08-16T12:58:34Z")
Hi,
Any advice how to get Kwh-meter pulse data from GPIO to node-red?
Im planning to use similar connection as this project: [Engineer's Principles: Power meter logging with Pi and Emoncms (skding.blogspot.com)](http://skding.blogspot.com/2015/01/power-meter-logging-with-pi-and-emoncms.html)
rpi - gpio in and rpi - gpio out nodes?
And how to count pulses to kW and kWh?
Br
Teemu
---
### Author:  [@sammachin](https://discourse.nodered.org/u/sammachin)
#### Post date: [16 August 2021 13:37 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/2 "2021-08-16T13:37:05Z")
I did some experimentation with this and I found that the PI's GPIO pins wern't accurate enough to detect the pulses from an LDR, so I ended up using a dedicated microcontroller to connect to the sensor then reading that into node-red on the pi over serial.
Have a look at [https://www.espruino.com/](https://www.espruino.com/)
---
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [20 August 2021 13:02 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/3 "2021-08-20T13:02:27Z")
Did you use node-red with raspberry and microcontroller? Could you share node-red script?
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [20 August 2021 16:38 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/4 "2021-08-20T16:38:55Z")
How often do the pulses come in?
---
### Author:  [@davidz](https://discourse.nodered.org/u/davidz)
#### Post date: [21 August 2021 15:23 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/5 "2021-08-21T15:23:16Z")
I have the same question too. PI's GPIO is not accurate in timing compared to FPGA, but it can still reach us (microsecond) level accuracy, which should be more than good enough to detect most pulses. But I don't know about timing accuracy of PI GPIO in Node-RED.
Unless he is checking the level of the light, in which case he needs an ADC.
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [21 August 2021 15:41 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/6 "2021-08-21T15:41:51Z")
My meter gives a pulse every 100 Wh so the timing accuracy is not important.
---
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [23 August 2021 05:15 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/7 "2021-08-23T05:15:44Z")
1000pulses / 1kwh. And measurement through S0 pins from kwh meter, not blinking light.
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [23 August 2021 06:19 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/8 "2021-08-23T06:19:28Z")
> [@TeemuJT](#):
>
> 1000pulses / 1kwh.
That doesn't answer the question unless you also tell us what the maximum load will be.
---
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [23 August 2021 06:32 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/9 "2021-08-23T06:32:31Z")
This is for testing purposes. For this case load is about 300w-1500w.
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [23 August 2021 07:30 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/10 "2021-08-23T07:30:19Z")
> [@TeemuJT](#):
>
> For this case load is about 300w-1500w
It doesn't matter what the test case is, what matters is what the system has to cope with.
---
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [23 August 2021 07:48 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/11 "2021-08-23T07:48:02Z")
16A is max current so 3600W is max load.
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [23 August 2021 10:39 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/12 "2021-08-23T10:39:27Z")
So, answering the question for you, that is a max of one pulse per second so a pi should have no difficulty with that, provided it is not heavily loaded with other stuff.
---
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [24 August 2021 09:35 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/13 "2021-08-24T09:35:27Z")
Any advice how to count pulses in node-red?
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [24 August 2021 19:21 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/14 "2021-08-24T19:21:39Z")
What end result are you trying to achieve?
On my system I don't add them up, I just write each pulse to influxdb as they come in. Then if I want the total for a period I get influx to calculate it.
---
### Author:  [@Paul-Reed](https://discourse.nodered.org/u/Paul-Reed)
#### Post date: [24 August 2021 20:01 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/15 "2021-08-24T20:01:07Z")
...or if you are not intending to use a database, you can save & increment the values in context (create a running total) see [Working with context : Node-RED](https://nodered.org/docs/user-guide/context)
As Colin has said, it depends what you intend to do with the data.
---
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [25 August 2021 05:10 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/16 "2021-08-25T05:10:10Z")
Just to see realtime consumption in dashboard and trend for 1-2days is enough.
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [25 August 2021 09:03 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/17 "2021-08-25T09:03:10Z")
> [@TeemuJT](#):
>
> realtime consumption
Again that does not fully define what you want. Is it real time power or accumulated total that you want?
---
### Author:  [@TeemuJT](https://discourse.nodered.org/u/TeemuJT)
#### Post date: [25 August 2021 09:14 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/18 "2021-08-25T09:14:45Z")
Realtime is enough
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [25 August 2021 09:24 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/19 "2021-08-25T09:24:58Z")
So all you need is the rate at which messages are coming in. If you search the node red flows site for 'speed' or 'rate' you will find a number of possible nodes. For example [node-red-contrib-msg-speed (node) - Node-RED](https://flows.nodered.org/node/node-red-contrib-msg-speed) might do what you want.
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [24 October 2021 09:25 UTC](https://discourse.nodered.org/t/raspberry-pi-and-node-red-kwh-meter-pulse-counting/49789/20 "2021-10-24T09:25:36Z")
This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.