PZEM004Tv40_R4

Arduino library for the PZEM-004T V4.0 (100A) Energy Monitor, compatible with Arduino UNO R3, R4, Nano, Mega, and other Arduino boards. This library enables easy reading of voltage, current, power, energy, frequency, power factor, and alarm status using the Modbus RTU protocol.

Features

• Full Parameter Support: Voltage, Current, Power, Energy, Frequency, Power Factor, Alarm Status
• Efficient Data Reading: Read all parameters with a single Modbus request
• Individual Parameter Access: Option to read specific parameters separately
• Energy Reset: Reset accumulated energy counter
• Address Management: Change device Modbus address for multi-device setups
• Built-in Error Handling: CRC verification and comprehensive error codes
• Universal Compatibility: Works with Arduino UNO R3, R4, Nano, Mega, and other boards
• Flexible Serial Communication: Supports both HardwareSerial (R4) and SoftwareSerial (R3/Nano)

Hardware Specifications

Supported Device: PZEM-004T-100A (V4.0)

Parameter	Measurement Range	Resolution
Voltage	80-260V AC	0.1V
Current	0-100A	0.001A
Power	0-23kW	0.1W
Energy	0-9999.99kWh	1Wh
Frequency	45-65Hz	0.1Hz
Power Factor	0.00-1.00	0.01

Communication: Modbus RTU, 9600 baud, 8N1

Installation

Arduino IDE

1. Download this repository as a ZIP file
2. In Arduino IDE, go to Sketch → Include Library → Add .ZIP Library
3. Select the downloaded ZIP file
4. Restart Arduino IDE

PlatformIO

Add to your platformio.ini:

lib_deps = 
    https://github.com/bharanidharanrangaraj/PZEM004Tv40_R4

Manual Installation

1. Clone or download this repository
2. Copy the PZEM004Tv40_R4 folder to your Arduino libraries directory:
   • Windows: Documents\Arduino\libraries\
   • MacOS: ~/Documents/Arduino/libraries/
   • Linux: ~/Arduino/libraries/

Wiring

Arduino UNO R4 (Minima/WiFi)

Connect the PZEM-004T to Arduino UNO R4:

PZEM-004T	Arduino UNO R4
TX	Pin 0 (RX / Serial1)
RX	Pin 1 (TX / Serial1)
5V	5V
GND	GND

Note: The PZEM-004T uses Serial1 on Arduino UNO R4, leaving the main USB serial (Serial) free for debugging.

Arduino UNO R3 / Nano / Mega

Connect the PZEM-004T to Arduino UNO R3/Nano:

PZEM-004T	Arduino UNO R3/Nano
TX	Pin 2 (RX / SoftwareSerial)
RX	Pin 3 (TX / SoftwareSerial)
5V	5V
GND	GND

Note: R3/Nano use SoftwareSerial for PZEM communication. You can change pins 2 and 3 to other digital pins if needed.

Quick Start

Arduino UNO R4

#include <PZEM004Tv40_R4.h>

// Create PZEM object on Serial1
PZEM004Tv40_R4 pzem(&Serial1);

void setup() {
  Serial.begin(115200);
  pzem.begin();
}

void loop() {
  // Read all parameters at once (recommended)
  if (pzem.readAll()) {
    Serial.print("Voltage: ");
    Serial.print(pzem.getVoltage(), 1);
    Serial.println(" V");
    
    Serial.print("Current: ");
    Serial.print(pzem.getCurrent(), 3);
    Serial.println(" A");
    
    Serial.print("Power: ");
    Serial.print(pzem.getPower(), 1);
    Serial.println(" W");
    
    Serial.print("Energy: ");
    Serial.print(pzem.getEnergy(), 3);
    Serial.println(" kWh");
  } else {
    Serial.print("Error: ");
    Serial.println(pzem.getLastError());
  }
  
  delay(1000);
}

Arduino UNO R3 / Nano

#include <SoftwareSerial.h>
#include <PZEM004Tv40_R4.h>

// Create SoftwareSerial for PZEM (RX=Pin2, TX=Pin3)
SoftwareSerial pzemSerial(2, 3);

// Create PZEM object on SoftwareSerial
PZEM004Tv40_R4 pzem(&pzemSerial);

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

void loop() {
  // Read all parameters at once (recommended)
  if (pzem.readAll()) {
    Serial.print("Voltage: ");
    Serial.print(pzem.getVoltage(), 1);
    Serial.println(" V");
    
    Serial.print("Current: ");
    Serial.print(pzem.getCurrent(), 3);
    Serial.println(" A");
    
    Serial.print("Power: ");
    Serial.print(pzem.getPower(), 1);
    Serial.println(" W");
  } else {
    Serial.print("Error: ");
    Serial.println(pzem.getLastError());
  }
  
  delay(1000);
}

API Reference

Constructor

PZEM004Tv40_R4(HardwareSerial* port, uint8_t addr = 0x01)

Creates a PZEM object with specified serial port and optional Modbus address.

Parameters:

• port: Pointer to hardware serial port (use &Serial1 for UNO R4)
• addr: Modbus address (default: 0x01, range: 0x01-0xF7)

Methods

Initialization

void begin()

Initialize the serial communication. Must be called in setup().

---

Read All Parameters (Recommended)

bool readAll()

Reads all parameters from PZEM in a single Modbus transaction. Most efficient method.

Returns: true if successful, false on error

Example:

if (pzem.readAll()) {
  // Access data using get methods
  float voltage = pzem.getVoltage();
  float current = pzem.getCurrent();
}

---

Get Cached Values

After calling readAll(), retrieve individual parameters:

float getVoltage()       // Returns voltage in V
float getCurrent()       // Returns current in A
float getPower()         // Returns power in W
float getEnergy()        // Returns energy in kWh
float getFrequency()     // Returns frequency in Hz
float getPowerFactor()   // Returns power factor (0.00-1.00)
bool getAlarm()          // Returns alarm status

---

Read Individual Parameters

Read single parameters (less efficient, requires separate Modbus request):

float readVoltage()      // Read and return voltage
float readCurrent()      // Read and return current
float readPower()        // Read and return power
float readEnergy()       // Read and return energy
float readFrequency()    // Read and return frequency
float readPowerFactor()  // Read and return power factor

Returns: Parameter value on success, -1.0 on error

---

Energy Reset

bool resetEnergy()

Resets the accumulated energy counter to zero.

Returns: true if successful, false on error

Example:

if (pzem.resetEnergy()) {
  Serial.println("Energy counter reset!");
}

---

Change Address

bool setAddress(uint8_t newAddr)

Changes the device Modbus address. Use with caution!

Parameters:

• newAddr: New address (range: 0x01-0xF7)

Returns: true if successful, false on error

Warning: Only connect ONE PZEM device when changing addresses. Multiple devices with the same address will cause communication conflicts.

---

Error Handling

uint8_t getLastError()

Returns the last error code.

Error Codes:

• 0: No error
• 1: Timeout - device did not respond
• 2: CRC error - corrupted data
• 3: Invalid response
• 4: No data available

Examples

The library includes three examples:

1. Basic_Reading_R4

Simple example for Arduino UNO R4 demonstrating all parameter reading via HardwareSerial (Serial1).

File → Examples → PZEM004Tv40_R4 → Basic_Reading_R4

2. Basic_Readings

Same basic reading example for Arduino UNO R3, Nano, and Mega using SoftwareSerial.

File → Examples → PZEM004Tv40_R4 → Basic_Readings

3. Individual_Parameters

Compares efficient readAll() method vs individual parameter reads with execution time comparison. Auto-detects board and uses the appropriate serial interface.

File → Examples → PZEM004Tv40_R4 → Individual_Parameters

Best Practices

✅ Do's

• Use readAll() for reading multiple parameters - it's much faster
• Cache values by calling readAll() once, then use get methods multiple times
• Check return values - always verify readAll() returns true
• Add delays between read operations (minimum 100ms recommended)
• Power cycle PZEM if communication issues persist

❌ Don'ts

• Don't read individual parameters frequently - use readAll() instead
• Don't change addresses with multiple devices connected
• Don't exceed 10 requests/second - PZEM needs time to process
• Don't ignore error codes - use getLastError() for debugging

Troubleshooting

Problem	Solution
No data received	Check wiring, ensure PZEM is powered, verify address
CRC errors	Check for loose connections, electromagnetic interference
Timeout errors	Increase delay between reads, check baud rate (9600)
Wrong readings	Ensure proper CT clamp installation, check phase wiring
Address change fails	Connect only ONE device, power cycle before retry

Performance

Execution Times (typical on Arduino UNO R4):

• readAll(): ~200ms (single Modbus request)
• Individual reads (6 parameters): ~1200ms (6 separate requests)

Recommendation: Use readAll() for 6x faster performance!

Multi-Device Setup

To use multiple PZEM devices:

1. Connect devices one at a time
2. Change each device to a unique address (0x01, 0x02, 0x03...)
3. Create multiple PZEM objects with different addresses:

PZEM004Tv40_R4 pzem1(&Serial1, 0x01);
PZEM004Tv40_R4 pzem2(&Serial1, 0x02);
PZEM004Tv40_R4 pzem3(&Serial1, 0x03);

Compatibility

Supported Boards

• ✅ Arduino UNO R4 Minima (HardwareSerial)
• ✅ Arduino UNO R4 WiFi (HardwareSerial)
• ✅ Arduino UNO R3 (SoftwareSerial)
• ✅ Arduino Nano (SoftwareSerial)
• ✅ Arduino Mega (HardwareSerial)
• ✅ Other Arduino boards with HardwareSerial or SoftwareSerial support

Not Supported

• ❌ ESP32/ESP8266 (Currently under development, support for these boards will be available in upcoming release)

Architectures

• AVR (avr) - UNO R3, Nano, Mega (uses SoftwareSerial)
• Renesas RA4M1 (renesas_uno) - UNO R4 (uses HardwareSerial)

License

This library is released under the MIT License.

Author

Bharani Dharan Rangaraj

• Email: [email protected]
• GitHub: @bharanidharanrangaraj

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Support

If you find this library helpful, please ⭐ star the repository!

For issues and feature requests, please use the GitHub Issues page.

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Version: 1.1.1
Last Updated: June 2026