Rasberry Pi - Tutorials - S7-1200 & Snap7 Python - Controlling the PLC Using Rpi GPIO

Long awaited video on how to use the Rpi GPIO to control aspects of the PLC.

Intro to controlling Raspberry Pi's GPIO using python:

Raspberry Pi - Tutorials - GPIOZero - Controlling LEDS Using Rpi GPIO

Using the snap7zero and gpiozero to control the S7-1200 PLC with the Raspberry Pi:

Rasberry Pi - Tutorials - S7-1200 & Snap7 Python - Controlling the PLC Using Rpi GPIO

Raspberry Pi - Python Snap7 - Mapping and Reading Datablocks

import snap7.client
from snap7.snap7types import *
from snap7.util import *


class DBObject(object):
    pass


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

db=\
"""
Temperature Real 0.0
Cold Bool 4.0
RPis_to_Buy Int 6.0
Db_test_String String 8.0
"""

def DBRead(plc,db_num,length,dbitems):
    data = plc.read_area(areas['DB'],db_num,0,length)
    obj = DBObject()
    for item in dbitems:
        value = None
        offset = int(item['bytebit'].split('.')[0])

        if item['datatype']=='Real':
            value = get_real(data,offset)

        if item['datatype']=='Bool':
            bit =int(item['bytebit'].split('.')[1])
            value = get_bool(data,offset,bit)

        if item['datatype']=='Int':
            value = get_int(data, offset)

        if item['datatype']=='String':
            value = get_string(data, offset)

        obj.__setattr__(item['name'], value)

    return obj

def get_db_size(array,bytekey,datatypekey):
    seq,length = [x[bytekey] for x in array],[x[datatypekey] for x in array]
    idx = seq.index(max(seq))
    lastByte = int(max(seq).split('.')[0])+(offsets[length[idx]])
    return lastByte


if __name__ == "__main__":
    plc = snap7.client.Client()
    plc.connect('10.10.55.109',0,0)
    itemlist = filter(lambda a: a!='',db.split('\n'))
    deliminator='\t'
    items = [
        {
            "name":x.split(deliminator)[0],
            "datatype":x.split(deliminator)[1],
            "bytebit":x.split(deliminator)[2]
         } for x in itemlist
    ]
    #get length of datablock
    length = get_db_size(items,'bytebit','datatype')
    meh = DBRead(plc,10,length,items)
    print """
    Cold:\t\t\t{}
    Tempeature:\t\t{}
    RPis_to_Buy:\t{}
    Db_test_String:\t{}
    """.format(meh.Cold,meh.Temperature,meh.RPis_to_Buy,meh.Db_test_String)
    plc.disconnect();

Python Snap7 S7-1200 Simple Reading/Writing Memory Example

import snap7.client as c
from snap7.util import *
from snap7.snap7types import *

def ReadMemory(plc,byte,bit,datatype):
    result = plc.read_area(areas['MK'],0,byte,datatype)
    if datatype==S7WLBit:
        return get_bool(result,0,bit)
    elif datatype==S7WLByte or datatype==S7WLWord:
        return get_int(result,0)
    elif datatype==S7WLReal:
        return get_real(result,0)
    elif datatype==S7WLDWord:
        return get_dword(result,0)
    else:
        return None

def WriteMemory(plc,byte,bit,datatype,value):
    result = plc.read_area(areas['MK'],0,byte,datatype)
    if datatype==S7WLBit:
        set_bool(result,0,bit,value)
    elif datatype==S7WLByte or datatype==S7WLWord:
        set_int(result,0,value)
    elif datatype==S7WLReal:
        set_real(result,0,value)
    elif datatype==S7WLDWord:
        set_dword(result,0,value)
    plc.write_area(areas["MK"],0,byte,result)

if __name__=="__main__":
    plc = c.Client()
    plc.connect('10.10.54.2',0,1)
    print ReadMemory(plc,420,0,S7WLReal)
    WriteMemory(plc,420,0,S7WLReal,3.141592)
    print ReadMemory(plc,420,0,S7WLReal)

    #DONE!!

Raspberry Pi - SCADA - Another Video Tutorial Snap7 Python for S7-1200 PLC

Another Simple snap7 Python Tutorial

Covers creating a simple example on turning on and off a PLC output.

 import snap7.client as c
 from snap7.util import *
 from time import sleep


 def WriteOutput(dev,bytebit,cmd):
     byte,bit = bytebit.split('.')
     byte,bit = int(byte),int(bit)
     data = dev.read_area(0x82,0,byte,1)
     set_bool(data,byte,bit,cmd)
     dev.write_area(0x82,byte,data)

 def main():
     myplc = snap7.client.Client()
     myplc.connect('10.10.54.2',0,1)
     for x in range(10):
         WriteOutput(myplc,'0.0',x%2==0) # turns true every other iteration
         sleep(1)

 if __name__ == "__main__":
     main()

New S7-1200 & Snap7 Walkthrough Video Uploaded

I'm going to try and start a series of videos on python snap7 tutorial using my Raspberry Pi.
Here's the setup walkthrough :-)
Youtube link: https://youtu.be/yJNEsI5KJxs

Subscribe to my channel to keep up to date  Channel Link

Let me know what kind of things you'd like to see in the series :-)

Enjoy!