2018 Latest DC 0-300V 100A Modbus RTU Solar Power Meter Energy Meter RS485 With 100A shunt and USB Cable

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Overview

This document describes the specification of the PZEM-003/017 DC communication module, the module is mainly used for measuring DC voltage, current, active power, frequency and energy consumption, the module is without display function, the data is read through the RS485 interface.

PZEM-003: Measuring Range 10A (Built-in Shunt)

PZEM-017: Measuring Range 50A,100A,200A,300A (the current range is depend on the external shunt specification )

1. Function description

1.1 Voltage

1.1.1 Measuring range:0.05-300V. (when the test voltage is <7V, please use the independent power supply mode)

1.1.2 Resolution:0.01V.

1.1.3 Measurement accuracy:1%.

1.2 Current

1.2.1 Measuring range:0.01-10A(PZEM-003);0.02-300A(PZEM-017;can be matched with 50,100,200,300A four kinds of shunt).

1.2.2 Resolution:0.01A

1.2.3 Measurement accuracy:1%

1.3 Power

1.3.1 Measuring range:0.1-3kW(PZEM-003);0.2-90kW(PZEM-017)

1.3.2 Resolution: 0.1W

1.3.3 Measurement accuracy:1%

1.4 Energy Consumption

1.4.1 Measuring range: 0-9999kWh

1.4.2 Resolution: 1Wh

1.4.3 Measurement accuracy:1%

1.4.4 Reset energy: use software to reset.

1.5 Over Voltage alarm

Voltage threshold can be set, divide into high voltage and low voltage threshold, when the measured voltage exceeds the threshold, it can alarm

The default high voltage threshold is 300V, the default low voltage threshold is 7V.

1.6 Communication interface

RS485 interface.

2. Communication protocol

2.1 Physical layer protocol

Physical layer use UART to RS485 communication interface.

Baud rate is 9600, 8 data bits, 2 stop bit, no parity.

2.2 Application layer protocol

The application layer use the Modbus-RTU protocol to communicate. At present, it only supports function codes such as 0x03 (Read Holding Register), 0x04 (Read Input Register), 0x06 (Write Single Register), 0x41 (Calibration), 0x42 (Reset energy).etc.

0x41 function code is only for internal use (address can be only 0xF8), used for factory calibration and return to factory maintenance occasions, after the function code to increase 16-bit password, the default password is 0x3721.

The address range of the slave is 0x01 ~ 0xF7. The address 0x00 is used as the broadcast address, the slave does not need to reply the master. The address 0xF8 is used as the general address, this address can be only used in single-slave environment and can be used for calibration etc.operation.

2.3 Read the measurement result

The command format of the master reads the measurement result is(total of 8 bytes):

Slave Address + 0x04 + Register Address High Byte + Register Address Low Byte + Number of Registers High Byte + Number of Registers Low Byte + CRC Check High Byte + CRC Check Low Byte.

The command format of the reply from the slave is divided into two kinds:

Correct Reply: Slave Address + 0x04 + Number of Bytes + Register 1 Data High Byte + Register 1 Data Low Byte + ... + CRC Check High Byte + CRC Check Low Byte

Error Reply: Slave address + 0x84 + Abnormal code + CRC check high byte + CRC check low byte

Abnormal code analyzed as following (the same below)

 0x01,Illegal function;

 0x02,Illegal address;

 0x03,Illegal data;

 0x04,Slave error.

The register of the measurement results is arranged as the following table

Register address Description Resolution

0x0000 Voltage value 1LSB correspond to 0.01V

0x0001 Current value 1LSB correspond to 0.01A

0x0002 Power value low 16 bits 1LSB correspond to 0.1W

0x0003 Power value high 16 bits

0x0004 Energy value low 16 bits 1LSB correspond to 1Wh

0x0005 Energy value high 16 bits

0x0006 High voltage alarm status 0xFFFF is alarm,0x0000 is not alarm

0x0007 Low voltage alarm status 0xFFFF is alarm,0x0000 is not alarm

For example, the master sends the following command (CRC check code is replaced by 0xHH and 0xLL, the same below):

0x01 + 0x04 + 0x00 + 0x00 + 0x00 + 0x08 + 0xHH + 0xLL

Indicates that the master needs to read 8 registers with slave address 0x01 and the start address of the register is 0x0000.

The correct reply from the slave is as following:

0x01 + 0x04 + 0x10 + 0x27 + 0x10 + 0x00 + 0x64 + 0x03 + 0xE8 + 0x00 + 0x00 + 0x00 + 0x00 + 0x00 + 0x00 + 0x00 + 0x00 + 0x00 + 0x00 + 0xHH + 0xLL

The above data shows

 Voltage is 0x2710,converted to decimal is 10000,display 100.00V;

 Current is 0x0064,converted to decimal is 100,display 1.00A;

 Power is 0x000003E8,converted to decimal is 1000,display 100.0W;

 Energy is 0x00000000,converted to decimal is 0,display 0Wh;

 High voltage alarm status 0x0000,indicates the current voltage is lower than the high voltage threshold.

 Low voltage alarm status 0x0000,indicates the current voltage is higher than the low voltage threshold.

2.4 Read and modify the slave parameters

At present,it only supports reading and modifying slave address and power alarm threshold

The register is arranged as the following table

Register address Description Resolution

0x0000 High voltage alarm threshold(5~350V),default is 300V 1LSB correspond to 0.01V

0x0001 Low voltage alarm threshold(1~350V),default is 7V 1LSB correspond to 0.01V

0x0002 Modbus-RTU address The range is 0x0001~0x00F7

0x0003 The current range(only for PZEM-017) 0x0000:100A

0x0001:50A

0x0002:200A

0x0003:300A

The command format of the master to read the slave parameters and read the measurement results are same(described in details in Section 3.3), only need to change the function code from 0x04 to 0x03.

The command format of the master to modify the slave parameters is (total of 8 bytes):

Slave Address + 0x06 + Register Address High Byte + Register Address Low Byte + Register Value High Byte + Register Value Low Byte + CRC Check High Byte + CRC Check Low Byte.

The command format of the reply from the slave is divided into two kinds:

Correct Response: Slave Address + 0x06 + Number of Bytes + Register Address Low Byte + Register Value High Byte + Register Value Low Byte + CRC Check High Byte + CRC Check Low Byte.

Error Reply: Slave address + 0x86 + Abnormal code + CRC check high byte + CRC check low byte.

For example, the master sets the slave's high voltage alarm threshold:

0x01 + 0x06 + 0x00 + 0x01 + 0x4E + 0x20 + 0xHH + 0xLL

Indicates that the master needs to set the 0x0001 register (low voltage alarm threshold) to 0x4E20(200.00V).

Set up correctly, the slave return to the data which is sent from the master.

For example, the master sets the low voltage alarm threshold of the slave

0x01 + 0x06 + 0x00 + 0x02 + 0x03 + 0xE8 + 0xHH + 0xLL

Indicates that the master needs to set the 0x0002 register (low voltage alarm threshold) to 0x03E8(10.00V).

Set up correctly, the slave return to the data which is sent from the master.

For example, the master sets the address of the slave

0x01 + 0x06 + 0x00 + 0x03 + 0x00 + 0x05 + 0xHH + 0xLL

Indicates that the master needs to set the 0x0003 register (Modbus-RTU address) to 0x0005

Set up correctly, the slave return to the data which is sent from the master.

2.5 Reset energy

The command format of the master to reset the slave's energy is (total 4 bytes):

Slave address + 0x42 + CRC check high byte + CRC check low byte.

Correct reply: slave address + 0x42 + CRC check high byte + CRC check low byte.

Error Reply: Slave address + 0xC2 + Abnormal code + CRC check high byte + CRC check low byte

2.6 Calibration

The command format of the master to calibrate the slave is (total 6 bytes):

0xF8 + 0x41 + 0x37 + 0x21 + CRC check high byte + CRC check low byte.

Correct reply: 0xF8 + 0x41 + 0x37 + 0x21 + CRC check high byte + CRC check low byte.

Error Reply: 0xF8 + 0xC1 + Abnormal code + CRC check high byte + CRC check low byte.

It should be noted that the calibration takes 3 to 4 seconds, after the master sends the command, if the calibration is successful, it will take 3 ~ 4 seconds to receive the response from the slave.

2.7 CRC check

CRC check use 16bits format, occupy two bytes, the generator polynomial is X16 + X15 + X2 +1, the polynomial value used for calculation is 0xA001.

The value of the CRC check is all results of a frame data checking divide CRC