最近要開發(fā)基于TCP/IP協(xié)議的西門子S7系列PLC的通訊和數(shù)據(jù)采集，網(wǎng)上搜羅了一圈發(fā)現(xiàn)有python snap7還有HSL這兩個工具，不過考慮到商用界限并且鑒于此次開發(fā)時間足夠，就自己研究上手了，

由于網(wǎng)上解決方案有限，查閱大部分資料只能查到讀一些I/O/M之類的接口，DB塊基本沒有...無賴只好啃manual。

基本上主要用snap7的read_area 、write_area兩個方法就可以實現(xiàn)，當(dāng)然接口眾多...我也就沒一一去了解，

廢話少說~~直接貼代碼：

#####################################################################

# equipmenthandler.py

#

# (c) Copyright 2013-2015, Benjamin Parzella. All rights reserved.

#

# This library is free software; you can redistribute it and/or

# modify it under the terms of the GNU Lesser General Public

# License as published by the Free Software Foundation; either

# version 2.1 of the License, or (at your option) any later version.

#

# This software is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU Lesser General Public License for more details.

#####################################################################

import struct

import snap7

from snap7.util import *

from snap7.snap7exceptions import Snap7Exception

from snap7.snap7types import *

import EAP.LogFile.communication_log_file_handler

db = \

"""DB001 Real 0.0 7.9

DB002 Bool 4.2 1

DB003 Int 6.0 12

DB004 String 8.0 0221190081

DB005 Real 264.0 9.69"""

offsets = {"Bool":2,"Int":2,"Real":4,"DInt":6,"String":256}

class DATAObject(object):

pass

class s7netcommunication:

def __init__(self,ip,port=102,rack=0,slot=0):

self.ip=ip

self.port=port

self.rack=rack

self.slot=slot

self.obj = DATAObject()

self.client = snap7.client.Client()

def Connect(self):

self.client.connect(self.ip, self.rack, self.slot,self.port)

def Disconnect(self):

self.client.disconnect()

def get_data_len(self,bytebit,datatype):

offset_int= []

offset_int.append(int(bytebit.split('.')[0]))

data_len = (max(offset_int))+ int(offsets[datatype])

return data_len

def ReadDBData(self,device_type,data_num,data_len,name,bytebit,datatype):

data=''

if device_type.upper() == 'I':

#data = self.client.read_area(0x81,data_num,0,data_len)

pass

elif device_type.upper() == 'Q':

#data = self.client.read_area(0x82,data_num,0,data_len)

pass

elif device_type.upper() == 'M':

data = self.client.read_area(0x83,data_num,0,data_len)

pass

elif device_type.upper() == 'DB':

data = self.client.read_area(0x84,data_num,0,data_len)

value = None

offset = int(bytebit.split('.')[0])

if datatype=='Real':

value = get_real(data,offset)

if datatype=='Bool':

bit = int(bytebit.split('.')[1])

value = get_bool(data,offset,bit)

if datatype=='Int':

value = get_int(data,offset)

if datatype=='String':

value = get_string(data,offset,256)

self.obj.__setattr__(name,value)

return self.obj

def WriteDBData(self,data_num,data_len,bytebit,datatype,value):

result = self.client.read_area(0x84,data_num,0,data_len)

byte_idx = int(bytebit.split('.')[0])

if datatype=='Bool':

bit_idx = int(bytebit.split('.')[1])

set_bool(result,byte_idx,bit_idx,value)

elif datatype=='Int':

set_int(result,byte_idx,value)

elif datatype=='Real':

set_real(result,byte_idx,value)

elif datatype=='String':

set_string(result,byte_idx,value,256)

self.client.write_area(0x84,data_num,0,result)

S7Net=s7netcommunication('192.168.0.1',102,0,0)

S7Net.Connect()

itemlist = filter(lambda a:a != ' ',db.split('\n'))

space = ' '

items = [{

"name":x.split(space)[0],

"datatype":x.split(space)[1],

"bytebit":x.split(space)[2],

"value":float(x.split(space)[3]) if (x.split(space)[1])=='Real' else (str(x.split(space)[3]) if (x.split(space)[1])=='String' else

(bool(int(x.split(space)[3])) if (x.split(space)[1])=='Bool' else

((int(x.split(space)[3]) if (x.split(space)[1])=='Int' else None))))

}for x in itemlist]

obj = DATAObject()

for x in items:

data_len = S7Net.get_data_len(x['bytebit'] ,x['datatype'])

S7Net.WriteDBData(1,data_len,x['bytebit'],x['datatype'],x['value'])

DATA_obj = S7Net.ReadDBData('DB',1,data_len,x['name'],x['bytebit'] ,x['datatype'])

print(DATA_obj.DB001,DATA_obj.DB002,DATA_obj.DB003,str(DATA_obj.DB004)[0:10],DATA_obj.DB005)

總結(jié)

以上是生活随笔為你收集整理的python snap7 plc db_python 用Snap7读写西门子PLC中DB块的全部內(nèi)容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網(wǎng)站內(nèi)容還不錯，歡迎將生活随笔推薦給好友。