如何解决西门子标志! PLC 数据顺序错误
所以我正在访问 Siemens logo! PLC从中提取一些数据。我设法与我的工作伙伴一起做到了这一点,但我们一直在关注如何保存数据。数据在字典中加上来自 PLC 的输出和输入字节的时间戳。但是数据是按一定顺序出现的,并且在提取数据时加上时间戳。
现在的问题是时间戳和数据的保存顺序与数据进入的顺序不同。在过程中的某个地方出错了(我认为),但我们似乎无法找到它。
这是我们使用的 Python 代码:
# initial testing to connect to a PLC
#connects to PLC save I/O into json format with timestamp
import snap7
import time
import ctypes
import math
import json
PLCip = "x.x.x.x" #input ip
Port = 000 # input port
Rack = 0
Slot = 1
size_to_read = 100
datadb = (ctypes.c_uint8 * size_to_read)()
#creates client and connect to plc,returns true if connected
Client = snap7.client.Client()
Client.connect(PLCip,Rack,Slot)
print("Connected:",Client.get_connected())
#converts sum INT to bits
def access_bit(data,num):
base = int(num // 8)
shift = int(num % 8)
return (data[base] & (1<<shift)) >> shift
#empty dict for storing I/O data
mydata = {}
#save data dict to json format
def save_to_file(stamp,input,output,file):
mydata[stamp] = {'input': input,'output': output}
with open(file,'a') as f:
json.dump(mydata,f)
while True:
# ts = time.time() #gets current time
_Now = time.time()
ts = time.localtime(_Now)
# timestamp = (time.strftime('%H:%M:%s',ts),str('%.3f'%_Now).split('.')[1])
timestamp = time.strftime('%X',ts)
datestamp = time.strftime('%d-%m-%Y',ts)
log_folder='logs/'
color=['black/','orange/','Metal/']
#json_file = str(log_folder)+str(datestamp)+'-'+str(timestamp)+'.json'
json_file = str(log_folder)+str(color[2])+str(datestamp)+'.json'
data = Client.eb_read(0,2) # reads input data from 2 bytes
data_input = format(int.from_bytes(data,"little"),"b") #converts from int to bits
outputdata = Client.ab_read(0,2) #reads output data from 2 bytes
data_output = format(int.from_bytes(outputdata,"b") #converts from int to bits
#save it to json file with parameters
save_to_file(timestamp,data_input,data_output,json_file)
#print to cli for debugging
print_text= "Time: {}\nInput: {}\nOutput: {}\n".format(timestamp,data_output)
print(print_text)
#wait 1 second and restart
time.sleep(1)
我们得到的数据:
{"13:41:57": {"input": "1001010000","output": "0"}}{"13:41:57": {"input": "1001010000","output": "0"},"13:41:58": {"input": "1001010000","13:41:59": {"input": "1001010000","13:42:00": {"input": "1001010000","13:42:01": {"input": "1001010000","output": "1001"}}{"13:41:57": {"input": "1001010000","output": "1001"},"13:42:02": {"input": "1010010000","output": "101"}}{"13:41:57": {"input": "1001010000","output": "101"},"13:42:03": {"input": "1010010000","13:42:04": {"input": "1001010000","13:42:05": {"input": "1001010001",
这是脚本的一次连续执行。正如您所看到的,时间戳并不是真正有序的。 谁能帮我们解决这个问题。也许你们能看到我看不到的东西。
非常感谢!
解决方法
我发现了为什么它如此重复数据包。
因为 dict
数据是在 while 循环之外定义的,所以它不断向 dict
添加新的键值。 dict
被包装到一个 json 文件中,并不断呈指数增长。
dict
数据需要在 while 循环中定义,以便每次将 dict
转储到 json 时都可以重复使用。
...
#save data dict to json format
def save_to_file(stamp,input,output,file):
mydata[stamp] = {'input': input,'output': output}
with open(file,'a') as f:
json.dump(mydata,f)
while True:
mydata={}
# ts = time.time() #gets current time
_now = time.time()
ts = time.localtime(_now)
# timestamp = (time.strftime('%H:%M:%S',ts),str('%.3f'%_now).split('.')[1])
timestamp = time.strftime('%X',ts)
datestamp = time.strftime('%d-%m-%Y',ts)
log_folder='logs/'
color=['black/','orange/','metal/']
...
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