It’s been a while now – I started logging data over the power usage back around 17th of April. I wanted to make sure that the script I was running was stable before writing about it.
In the beginning I noticed a few times where the script terminated without any good reason. I think the reason now was due to some changes in my network setup. The raspberry Pi REALLY does not like when the IP address in the middle of a data transmission. Well, The network have been stable and now I think I can safely say that this is the script that I will continues to use.
Yes, I know – the rPi is really overkill for this application – I would like to use an ESP8266. The system is using the Wi-Fi anyway. But for now I will stick with this I continue to get data into my database and I am happy with it.
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import time, threading import serial import struct import http.client #so far this script only allows a single SDM630 device on the network. Expand the functionality by changing the address deviceAddress = 1 apiKey= 'insert-secret-api-here' serverAddress = '192.168.xxx.xxx' #the server address (mine is local) # #Read the first 37 registers of the SDM630 device. this should cover the basic meter information # def readRegisters(deviceAddress): packet = [ 1, 4, 0, 0, 0, 74] #address 1, mode 04, register 00, requesting 74 bytes CRC = computeCrc(packet) #calculate the CRC of the packet and append it. packet.append(CRC&0x00FF) packet.append(CRC>>8) try: port = serial.Serial("/dev/ttyUSB0", baudrate=9600, parity=serial.PARITY_NONE, timeout= 3) port.write(packet) time.sleep(1) s = port.read(port.inWaiting()) s= s[8:] port.flushInput() return s except: print('modbus error') return -1 # #Use a lookup table to calculate the CRC value for the incoming packet of data # def computeCrc(data): crc = 0xFFFF for i in range(0,len(data)): crc = ((crc >> 8) ^ CrcTable[(crc ^ data[i]) & 0xFF]); return crc CrcTable = [ 0X0000, 0XC0C1, 0XC181, 0X0140, 0XC301, 0X03C0, 0X0280, 0XC241,0XC601, 0X06C0, 0X0780, 0XC741, 0X0500, 0XC5C1, 0XC481, 0X0440, 0XCC01, 0X0CC0, 0X0D80, 0XCD41, 0X0F00, 0XCFC1, 0XCE81, 0X0E40,0X0A00, 0XCAC1, 0XCB81, 0X0B40, 0XC901, 0X09C0, 0X0880, 0XC841, 0XD801, 0X18C0, 0X1980, 0XD941, 0X1B00, 0XDBC1, 0XDA81, 0X1A40,0X1E00, 0XDEC1, 0XDF81, 0X1F40, 0XDD01, 0X1DC0, 0X1C80, 0XDC41, 0X1400, 0XD4C1, 0XD581, 0X1540, 0XD701, 0X17C0, 0X1680, 0XD641,0XD201, 0X12C0, 0X1380, 0XD341, 0X1100, 0XD1C1, 0XD081, 0X1040, 0XF001, 0X30C0, 0X3180, 0XF141, 0X3300, 0XF3C1, 0XF281, 0X3240,0X3600, 0XF6C1, 0XF781, 0X3740, 0XF501, 0X35C0, 0X3480, 0XF441, 0X3C00, 0XFCC1, 0XFD81, 0X3D40, 0XFF01, 0X3FC0, 0X3E80, 0XFE41,0XFA01, 0X3AC0, 0X3B80, 0XFB41, 0X3900, 0XF9C1, 0XF881, 0X3840, 0X2800, 0XE8C1, 0XE981, 0X2940, 0XEB01, 0X2BC0, 0X2A80, 0XEA41,0XEE01, 0X2EC0, 0X2F80, 0XEF41, 0X2D00, 0XEDC1, 0XEC81, 0X2C40, 0XE401, 0X24C0, 0X2580, 0XE541, 0X2700, 0XE7C1, 0XE681, 0X2640,0X2200, 0XE2C1, 0XE381, 0X2340, 0XE101, 0X21C0, 0X2080, 0XE041, 0XA001, 0X60C0, 0X6180, 0XA141, 0X6300, 0XA3C1, 0XA281, 0X6240,0X6600, 0XA6C1, 0XA781, 0X6740, 0XA501, 0X65C0, 0X6480, 0XA441, 0X6C00, 0XACC1, 0XAD81, 0X6D40, 0XAF01, 0X6FC0, 0X6E80, 0XAE41,0XAA01, 0X6AC0, 0X6B80, 0XAB41, 0X6900, 0XA9C1, 0XA881, 0X6840, 0X7800, 0XB8C1, 0XB981, 0X7940, 0XBB01, 0X7BC0, 0X7A80, 0XBA41,0XBE01, 0X7EC0, 0X7F80, 0XBF41, 0X7D00, 0XBDC1, 0XBC81, 0X7C40, 0XB401, 0X74C0, 0X7580, 0XB541, 0X7700, 0XB7C1, 0XB681, 0X7640,0X7200, 0XB2C1, 0XB381, 0X7340, 0XB101, 0X71C0, 0X7080, 0XB041, 0X5000, 0X90C1, 0X9181, 0X5140, 0X9301, 0X53C0, 0X5280, 0X9241,0X9601, 0X56C0, 0X5780, 0X9741, 0X5500, 0X95C1, 0X9481, 0X5440, 0X9C01, 0X5CC0, 0X5D80, 0X9D41, 0X5F00, 0X9FC1, 0X9E81, 0X5E40,0X5A00, 0X9AC1, 0X9B81, 0X5B40, 0X9901, 0X59C0, 0X5880, 0X9841, 0X8801, 0X48C0, 0X4980, 0X8941, 0X4B00, 0X8BC1, 0X8A81, 0X4A40,0X4E00, 0X8EC1, 0X8F81, 0X4F40, 0X8D01, 0X4DC0, 0X4C80, 0X8C41, 0X4400, 0X84C1, 0X8581, 0X4540, 0X8701, 0X47C0, 0X4680, 0X8641,0X8201, 0X42C0, 0X4380, 0X8341, 0X4100, 0X81C1, 0X8081, 0X4040] if __name__ == "__main__": try: while True: registerValues =[] s=readRegisters(deviceAddress) if len(s) > 5: for i in range(37): data = s[3+(4*i):(3+(4*i))+4] registerValues.append(format(struct.unpack('>f',data)[0],'.5f')) #print ('register ' + str(i+1) + ': ' + str(format(struct.unpack('>f',data)[0],'.5f'))) #generate HTTP request req = '/rest/catch/meterCatch.php?API='+apiKey+'&data=' for i in range(36): req += str(registerValues[i])+',' req+=str(registerValues[36]) conn = http.client.HTTPConnection(serverAddress, 80) #open connection to server conn.request("GET",req) #perform the request print(req) print(conn.getresponse().status) else: print('modbus read error - data too short') time.sleep(29) except KeyboardInterrupt: print('KeyboardInterrupt') pass |
I THINK the script is not using any special libraries apart maybe from the pySerial that I needed to install.
In all its simplicity the script reads 37 registers (74 bytes) from the RS-485 device with address 01. This is the Eastron device. This is done every 29th second. There is a timeout of 1 second in the reading routine so data should come approximately every half minute into the DB. The data is sent using a REST interface (homegrown) and the PHP catch page is inserting the timestamp and separating the data. For now I am only saving the following:
- Voltage per phase
- Current per phase
- Power per phase
- Total power
- Total accumulated power
- Frequency
I could log a lot more data but it just seems a bit… over the top and I really don’t know what I would do with the info.
The interface is a FTDI USB-to-Serial converter along with an RS-485 interface chip.