PZEM004T-V4.0 not working with multiple PZEMS

[sanskarjangid]

Previously the library was working fine with V 3.0, but with V4.0 if I connect one pzem it gives the reading but if I connect more than one in parralel, the output is NaN. Does this library not support the newer version? Or are there any major hardware changes in new version of PZEM004T

[barman75]

I had the same issues with a V04 - in parralel connection I could only get data from one device simultaniousely. Solved by adding zener diodes to the TX. The code is basically simple, but do some checks.

Buy the way, new V04 is way better for non-sinus or step approximation of a sinusoid voltage.
In old v03 power scheme the power dissipated on the current-limiting resistor, and with an input voltage of 230V and a 0.47uF capacitor, the current limiting resistor will dissipate approximately 2.5W. But Chinese uses barely 1W resistors

#include <SoftwareSerial.h>
#include <PZEM004Tv30.h>

#define RX_PIN 8
#define TX_PIN 9

SoftwareSerial pzemSerial(RX_PIN, TX_PIN);

// Ініціалізуємо два пристрої з різними адресами
PZEM004Tv30 pzem1(pzemSerial, 0x10);
PZEM004Tv30 pzem2(pzemSerial, 0x11);

unsigned long lastReadTime = 0;
const unsigned long readInterval = 1000; // Читати кожні 1 сек

void setup() {
  Serial.begin(115200);
  pzemSerial.begin(9600);

  Serial.println("Start readning PZEM-004T v4.0 (0x10 і 0x11)");
}

void loop() {
  unsigned long currentMillis = millis();
  if (currentMillis - lastReadTime >= readInterval) {
    lastReadTime = currentMillis;

    Serial.println("-----");

    // ==== Опитування першого пристрою (0x10) ====
    float voltage1 = pzem1.voltage();
    float current1 = pzem1.current();
    float power1   = pzem1.power();

    if (!isnan(voltage1) && voltage1 > 50 && voltage1 < 300 &&
        !isnan(current1) && !isnan(power1)) {
      Serial.println("PZEM 0x10:");
      Serial.print("  Voltage1: "); Serial.print(voltage1); Serial.println(" В");
      Serial.print("  Current:   "); Serial.print(current1); Serial.println(" А");
      Serial.print("  Power: "); Serial.print(power1);   Serial.println(" Вт");
    } else {
      Serial.println("Error reading PZEM 0x10");
    }

    // ==== Опитування другого пристрою (0x11) ====
    float voltage2 = pzem2.voltage();
    float current2 = pzem2.current();
    float power2   = pzem2.power();

    if (!isnan(voltage2) && voltage2 > 50 && voltage2 < 300 &&
        !isnan(current2) && !isnan(power2)) {
      Serial.println("PZEM 0x11:");
      Serial.print("  Voltage2: "); Serial.print(voltage2); Serial.println(" В");
      Serial.print("  Current:   "); Serial.print(current2); Serial.println(" А");
      Serial.print("  Power.: "); Serial.print(power2);   Serial.println(" Вт");
    } else {
      Serial.println("Error reading PZEM 0x11");
    }

    Serial.println("-----");
  }

}

[flim-th]

What number zener diode or use diode