Power measurement and logger using Rpi+PZEM016+influxDB+Grafana

Bhuris Sridurongrit

5 min readAug 18, 2020

Hello, I’m Bhuris, This is my first Medium story I will show my practice including the fixed issue.

Key Words: Electrical power measurement, Modbus RTU interface with Rpi,

check this out → https://github.com/bhuris/modbusreadpzem016

WARNING !!!

THIS PROJECT WORKS WITH MAINS VOLTAGE !!!

YOUR SAFETY AND YOUR PROPERTY IS YOUR RESPONSIBILITY. !!!

Read this → https://hackaday.com/2016/05/16/looking-mains-voltage-in-the-eye-and-surviving-part-2/

Introduction

I need the telemetry system and logging of my local grid usage in a part of my home automation project with my requirements below

Real-time logging (Interval 0.5–1 S)
High Reliable for 24/7
Low Power consumption
Able to connect to time series database (this case in influx DB)
simplicity

Hardware Need

Raspberry Pi 3B+ or 4 and USB Charger
PZEM 016 Module
USB to RS485
Misc (Enclosure Box, wiring cable, control wiring cable, etc)

Prerequisites

Influx database, Grafana
some Node-red and Python Familiar
Basic Linux commands

Hardware review

PZEM016 (I got this from https://www.aliexpress.com/item/32862049796.html)

this is very handy and … module from China they arrive in a week !!

USB to RS485 Converter Module

Set Up Raspberry pi

Use Raspberry Pi Imager to flash the SD card for Raspbian 32bit
Add ssh file(without any file extension) for enable ssh
Insert SD card to raspberry pi
Power Up and connect Ethernet cable to RPi
Find the Rpi IP address from DHCP Lease section on you Firewall/Router
ssh to raspberry pi (enter ssh pi@<your-pi-ip-address>) then enter default password ‘raspberry’
Install node-red and setup
copy Python File to the desired directory

9. Insert USB-RS485 to RPi and Start Terminal then run ‘lsusb’ command and you should see a USB device.

pi@iotnode554b:~ $ lsusb
Bus 001 Device 004: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter
Bus 001 Device 005: ID 0424:7800 Standard Microsystems Corp.
Bus 001 Device 003: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hubpi@iotnode554b:~ $ ls /dev/tty*
/dev/tty    /dev/tty19  /dev/tty3   /dev/tty40  /dev/tty51  /dev/tty62
/dev/tty0   /dev/tty2   /dev/tty30  /dev/tty41  /dev/tty52  /dev/tty63
/dev/tty1   /dev/tty20  /dev/tty31  /dev/tty42  /dev/tty53  /dev/tty7
/dev/tty10  /dev/tty21  /dev/tty32  /dev/tty43  /dev/tty54  /dev/tty8
/dev/tty11  /dev/tty22  /dev/tty33  /dev/tty44  /dev/tty55  /dev/tty9
/dev/tty12  /dev/tty23  /dev/tty34  /dev/tty45  /dev/tty56  /dev/ttyAMA0
/dev/tty13  /dev/tty24  /dev/tty35  /dev/tty46  /dev/tty57  /dev/ttyprintk
/dev/tty14  /dev/tty25  /dev/tty36  /dev/tty47  /dev/tty58  /dev/ttyUSB0
/dev/tty15  /dev/tty26  /dev/tty37  /dev/tty48  /dev/tty59
/dev/tty16  /dev/tty27  /dev/tty38  /dev/tty49  /dev/tty6
/dev/tty17  /dev/tty28  /dev/tty39  /dev/tty5   /dev/tty60
/dev/tty18  /dev/tty29  /dev/tty4   /dev/tty50  /dev/tty61

10. Set port and Modbus RTU slave address (default is 0x01) on python file

port='/dev/ttyUSB0'
unit = '0x01'

11. Connect RS485 between PZEM and USB to RS485 dongle

wiring main voltage into PZEM and clamp the CT to power wire

12. Run a test

pi@iotnode554b:~/Desktop/eepanelpgm $ python3 readmodbus.py
{"volt": 226.20000000000002, "amp": 7.088, "realpower": 1566.9, "energy": 24.899, "freq": 49.900000000000006, "pwfac": 0.98, "reactive": 318.17261534742113, "apparent": 1598.8775510204082, "powerangle": 0.20033484232311968, "impedance": 31.824954184089954, "rinline": 31.188455100408156, "xinline": 6.333085919932656, "status": "NORMAL JA"}

13. Create new influx DB User and database

> influx> CREATE DATABASE "eepanelgridmeas"
> user create -n johnkerry -p PaSsWoRd -o example-org## (Optional) Set Retention Policy for limiting database oversize> CREATE RETENTION   POLICY "one_day_only" ON "eepanelgridmeas" DURATION   23h60m REPLICATION 1 DEFAULT
> SHOW   RETENTION POLICIES ON "eepanelgridmeas"

For more Influx command Link

14. Set up InfluxDB on Node-red

enter you own Measurement (it’s automatically created on that database)
add a firewall rule to allows for port 8086

15. Add new data source on Grafana

16. Layout you dashboard

17. Add some time series chart for “ aesthetic ”

this nasty box is not an “ aesthetic ” one LOL

Recommend: Add a fuse between PT line for additional safety!

If you have a question or suggestion please let me know on GitHub !!

Issue

Wifi Connection lose after a long time and AP restart

Cause: WLAN power management feature set has been set to on by default

Then: disable this feature to prevent Wlan turn off automatically

### backup original file 
> sudo cp   /etc/network/interfaces /etc/network/interfaces.backup       ### Now edit the original   interfaces file:       
> sudo nano   /etc/network/interfaces## add this code to file
## Assuming   you haven’t edited this file before all you need to do is delete its entire   contents, and copy the following into it:       auto lo              
iface lo inet loopback       
iface eth0 inet dhcp              
auto wlan0       
allow-hotplug wlan0       
iface wlan0 inet dhcp       
wpa-conf   /etc/wpa_supplicant/wpa_supplicant.conf       
wireless-power off       
iface default inet dhcp       ## The important block of code   here is:       
auto wlan0       
allow-hotplug wlan0       
iface wlan0 inet dhcp       
wpa-conf   /etc/wpa_supplicant/wpa_supplicant.conf       
wireless-power off       
iface default inet dhcp## Thx to this blog https://thepihut.com/blogs/raspberry-pi-tutorials/disable-wifi-power-management

Rpi won’t start when using switching power supply

Cause: SMPS is usually generating the inference to sensitive device

then: insert 0.1uF ceramic between DC bus and use a shielded cable, also take a distance btw device and SMPS

check out this → https://github.com/bhuris/modbusreadpzem016