UPDATE: If you want the raspberry pi to be the s7 server go here
UPDATE 2: If you want to see communication with S7-200
go here
UPDATE 3: Video walkthrough on setup go here
I recently borrowed a
S7-1200 PLC
from work to see if I could get data from it using a
Raspberry Pi
. In my search for something I found that Snap7 was the best option.
Steps to getting it work
- Download and compile snap7 (http://sourceforge.net/projects/snap7/files/1.2.1/snap7-full-1.2.1.tar.gz/download)
- Download and install python library to use snap7 (https://pypi.python.org/pypi/python-snap7)
#download and compile snap7 for rpi
wget http://sourceforge.net/projects/snap7/files/1.2.1/snap7-full-1.2.1.tar.gz/download
tar -zxvf snap7-full-1.2.1.tar.gz
cd snap7-full-1.2.1/build/unix
sudo make –f arm_v6_linux.mk all
#copy compiled library to your lib directories
sudo cp ../bin/arm_v6-linux/libsnap7.so /usr/lib/libsnap7.so
sudo cp ../bin/arm_v6-linux/libsnap7.so /usr/local/lib/libsnap7.so
#install python pip if you don't have it:
sudo apt-get install python-pip
sudo pip install python-snap7
You will need to edit the lib_location on common.py in the /usr/local/lib/python2.7/dist-packages/snap7/ directory
Add a line in the __init__ part of the Snap7Library class:
lib_location='/usr/local/lib/libsnap7.so'
example below:
class Snap7Library(object):
"""
Snap7 loader and encapsulator. We make this a singleton to make
sure the library is loaded only once.
"""
_instance = None
def __new__(cls, *args, **kwargs):
if not cls._instance:
cls._instance = object.__new__(cls)
cls._instance.lib_location = None
cls._instance.cdll = None
return cls._instance
def __init__(self, lib_location=None):
lib_location='/usr/local/lib/libsnap7.so' # add this line here
if self.cdll:
return
self.lib_location = lib_location or self.lib_location or find_library('snap7')
if not self.lib_location:
msg = "can't find snap7 library. If installed, try running ldconfig"
raise Snap7Exception(msg)
self.cdll = cdll.LoadLibrary(self.lib_location)
Now you can write your client code :-)
Here's an example on how to connect and read an output Q0.0:
from time import sleep
import snap7
from snap7.util import *
import struct
plc = snap7.client.Client()
plc.connect("192.168.12.73",0,1)
area = 0x82 # area for Q memory
start = 0 # location we are going to start the read
length = 1 # length in bytes of the read
bit = 0 # which bit in the Q memory byte we are reading
byte = plc.read_area(area,0,start,length)
print "Q0.0:",get_bool(mbyte,0,bit)
plc.disconnect()
I created a helper class on my github here to make the syntax easier for people who are used to DAServer and Ladder:
https://github.com/SimplyAutomationized/raspberrypi/raw/master/S7-1200pi/S71200.py
Example on how to use it:
import S71200
from time import sleep
import snap7
from snap7.util import *
import struct
plc = S71200.S71200("192.168.21.65")
plc.writeMem('QX0.0',True) # write Q0.0 to be true, which will only turn on the output if it isn't connected to any rung in your ladder code
print plc.getMem('MX0.1') # read memory bit M0.1
print plc.getMem('IX0.0') # read input bit I0.0
print plc.getMem("FREAL100") # read real from MD100
print plc.getMem("MW20") # read int word from MW20
print plc.getMem("MB24",254) # write to MB24 the value 254
plc.plc.disconnect()
Let me know if there are questions. Hope I can help :-)
Also let me know if you can help me clean up my S71200.py helper class. I know it looks messy.
Follow me to get updates on a Raspberry pi Sensor the DA or OPC server can get data using S7 protocol.
+Simply Automationized
Check out my other SCADA posts
for $50
for $172 
for $335
for $8). What's great about the Pi is that is can handle tons of sensors and you can map it out it your programming. Keep in mind that none of these solutions are hardened for the industrial environment (although neither is the Raspberry pi....)
$7 (*
for the pi that wasn't so large. I'm going to be adding a 24vdc to 5vdc dc-dc converter to the enclosure it so I don't have to bring in usb to it. 
:
:
:
