Insulation monitoring module

1 Overview

QGDCG-UBC series products are devices used for online monitoring of the positive and negative ground insulation resistance values of DC floating systems.It is based on the principle of unbalanced bridge, which avoids the problem of undetectable ground faults in balanced bridges when the positive and negative values are relatively high. At the same time,This series of products can accurately measure the resistance value under the condition of large changes in DC voltage, and the measurement cycle is short, usingThe method of adaptively adjusting the measurement time avoids the influence of the positive and negative ratio on the ground capacitance.The measurement conditions of this series of products are DC system 150-1000V, resistance range 1KΩ~30MΩ, and they can also detectTo measure the DC voltage value, the user can obtain the measured value through RS485 communication. After 5 seconds after the module works, the userStable insulation resistance values can be read.

2 Function introduction

2.1 Terminals

2.2 Indicator light

Operation: The heartbeat indicator light lights up and off once every 1 second after power is supplied. It is abnormal if it is always on or off.

Communication: After correctly receiving the data sent by the host, it will flash once.

Measurement: It is always on when the module is measuring the insulation resistance of the current system. Generally, it stays on for about 5 seconds in a measurement cycle.

2.3 RS485 communication

Users can send data frames through the RS485 communication port to: modify the baud rate, control the start and stop of insulation measurement,

Read the measurement results. It is recommended that the data sending interval of each frame be greater than 100ms.

The default baud rate is 9600bps, no validation, 8-bit data, 1 stop bit. Support baud rate 1200, 2400, 4800,

9600, 14400, 19200, 38400, supports no parity, odd parity and even parity.

The baud rate is modified using the communication protocol, and the check digit is modified using the DIP switch.

2.4 DIP switch

Communication address DIP switch is used to configure the communication address, as follows:

Recommended A gun address: 10, Recommended B gun address: 11, Recommended C gun address: 12, Recommended D gun address: 13, if other special addresses are needed, the modification program can be customized!

Parity DIP switch is used to configure communication parity bits, as follows:

When the DIP switch is configured to the default value, the communication rate is directly modified to the default value. The default baud rate is 9600bps.No validation, 8-bit data, 1 stop bit, and save the parameters. After changing to the default value for 3 seconds, please dial back the required parameter configuration.setting, it is not recommended to stay in the default dialing position.

3 Dimensions and installation methods

4 Electrical parameters

System DC voltage range: 150V~1000V (within this range, monitor the positive and negative impedance to ground)

Power supply: 9~28VDC, 3W, 12v or 24v power supply recommended.

Insulation resistance measurement range: 1KΩ~30MΩ

Accuracy: Measurement error <10% within the range of 10KΩ~500KΩ.

Environmental parameters:

Storage temperature……………………-40℃~85℃

Working temperature…………………………………………-40℃~70℃

Humidity…………………………………………85%

Detection interval: >=5 seconds

Communication frequency: recommended to be greater than 100ms

5 Communication protocol

5.1 Agreement details and examples

Table 1 Description of data instructions sent by the host to this module

The meaning of each part in the table:

Addr: slave address

Fun: Function code 01: Read data from slave 02: Write data to slave

No_data hi: This byte is not operated. Generally, it can be written as 00H. See the example for details.

Reg_data: write data address

data hi: write the high bit of data

data lo: write the low bit of data

CRC hi: cyclic redundancy check high bit

CRC lo: cyclic redundancy check low bit

Table 2 Turn on insulation monitoring (sent by the host, no response from the module)

Reg_data：02H

Datalo: 20H (bit5=0: Insulation monitoring control bit, the grounding switch is closed, and the module starts to work)

Table 2 Turn off insulation monitoring (sent by the host, no response from the module)

Reg_data：02H

Datalo: 00H (bit5=0: Insulation monitoring control bit, the grounding switch is disconnected, and the module stops working)

Table 3 Modify the baud rate (sent by the host, no response is returned from the module)

Reg_data：01H

Datahi Datalo = 0X0341H (baud rate 1200 bps)

Datahi Datalo = 0X01A0H (baud rate 2400bps)

Datahi Datalo = 0X00d0H (baud rate 4800bps)

Datahi Datalo = 0X0068H (baud rate 9600bps)

Datahi Datalo = 0X0045H (baud rate 14400bps)

Datahi Datalo = 0X0034H (baud rate 19200bps)

Datahi Datalo = 0X001AH (baud rate 38400bps)

Note: If the parity dial switch is configured as the default bit, directly modify the baud rate to 9600 and save the parameters.

Table 4.1 Reading insulation monitoring data (sent by host)

Note: The green data in the table is fixed command data.

Table 4.2 Reading insulation monitoring data (slave module response)

data1:0x01f4 0X01F4=500, that is, the system DC voltage is 500V.

data2:0XFFFF 0XFFFF=65535, that is, the positive ground resistance is infinite (unit kΩ).

data3:0X0032 0X0032=50, that is, the negative ground resistance value is 50kΩ (unit kΩ).

Fun : 0x30

Among them bit5: Insulation monitoring work command status bit

0=Stop insulation monitoring, 1=Start insulation monitoring

Among them bit4: Insulation monitoring data reading status bit

0=Module insulation monitoring has not been completed, and it is not recommended to read the ground resistance value.

1=Module insulation monitoring has been completed and the ground resistance value can be read.

Note: After sending the instruction to turn on insulation monitoring, read bit4 bit cyclically. If this bit = 1, then

This indicates that the insulation measurement has been completed and the measurement results can be read. It usually takes more than 5s

After time, this bit is set to 1.

The other bits are spare bits.

5.2 CRC function

const unsigned char CRCHi[256]=

{

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40

};

const unsigned char CRCLo[256]=

const unsigned char CRCHi[256]=

{

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40

};

const unsigned char CRCLo[256]=

{

0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3, 0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26, 0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5, 0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C, 0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83, 0x41, 0x81, 0x80, 0x40

};

unsigned short chkcrc(unsigned char *pcData,unsigned char cDataLeng)

{

unsigned int iTemp=0;

unsigned char cCRCHi = 0xFF ;

unsigned char cCRCLo = 0xFF ;

unsigned char cIndex ;

while (cDataLeng--)

{

cIndex = cCRCHi ^ *pcData++ ;

cCRCHi = cCRCLo ^ CRCHi[cIndex] ;

cCRCLo = CRCLo[cIndex] ;

}

iTemp+=cCRCHi;

iTemp<<=8;

iTemp+=cCRCLo;

return (iTemp);

}