Panasonic の電力計 kw2g から rs485 でデータを読む

ＲＴコマンド を送って、リスポンスを受け取るサンプルです。
プロトコルは MEWTOCOL です。

kw2g.py

#! /usr/bin/python3
#
#       kw2g.py
#
#                                               Dec/07/2019
#
#
# ------------------------------------------------------------------
import  serial
import  time
import  sys

# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
ser = serial.Serial(port='/dev/ttyUSB0', baudrate=19200,bytesize=8,parity='O',stopbits=1,timeout = 1)
#
data = ['%','0','1','#','R','T','*','*','\r','\n']
data_int = []
for it in range(len(data)):
        uu = ord(data[it])
        data_int.append(uu)
#
ser.write(bytearray(data_int))
#
time.sleep(0.5)
#
response = []
while True:
        try:
                sys.stderr.write("*** reading ***\n")
                bytesAvailable = ser.inWaiting()
                sys.stderr.write("%d bytes available to read\n" % bytesAvailable)
                response = ser.readline()
                break
        except KeyboardInterrupt:
                break
#
str_hex = "hex: "
str_out = "chr: "
for it in range(len(response)):
        str_hex += " %02x" % response[it]
        str_out += "  %c" % response[it]
print(str_hex)
print(str_out)
ser.close()
#
sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

実行結果

$ ./kw2g.py 
*** 開始 ***
*** reading ***
25 bytes available to read
chr:  25 30 31 24 52 54 39 39 34 30 30 31 30 33 30 31 30 30 30 30 30 30 30 31 0d
hex:   %  0  1  $  R  T  9  9  4  0  0  1  0  3  0  1  0  0  0  0  0  0  0  1  
*** 終了 ***