用modbus-tk,来读取功率仪的704地址的数据,想实现每隔三秒读取一次,求教该怎么编写循环程序,目前已实现单次读取,程序如下:
import serial
import modbus_tk
import modbus_tk.defines as cst
from modbus_tk import modbus_rtu
import time
def sleeptime(hour,min,sec):
return hour*3600 + min*60 + sec
second = sleeptime(0,0,3)
time.sleep(second)
master = modbus_rtu.RtuMaster(
serial.Serial('COM8', baudrate=19200, bytesize=8, parity='N', stopbits=1)
)
master.set_timeout(5.0)
data = master.execute(1, cst.READ_HOLDING_REGISTERS, 704, 1)
print (data)