Basic python code with PLC

I like to understand and know how to write a basic python code to connect and interact with Siemens PLC S7-300 and S7-1200 using Snap7. Please kindly guide me on what to do step by step!

FUMMY said:

I like to understand and know how to write a basic python code to connect and interact with Siemens PLC S7-300 and S7-1200 using Snap7. Please kindly guide me on what to do step by step!

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Step 1, learn python.
Step 2, Read the documentation on S7-300 and S7-1200, especially the communication options.
Step 3, Read the documentation on python modules.
Step 4, purchase the appropriate equipment.
Step 5, code and test.

I recommend https://learnpythonthehardway.org/ for Python basics. Way down at the bottom of the page there is a small link to view the HTML version of the book if you don't want to pay for it.

I'd learn the basics first. Then maybe you could check out this:

https://pypi.python.org/pypi/python-snap7/

I don't really know anything about it, or Siemens, I just googled it.

Also...
Khan Academy has free online classes for Python!

I love Khan Academy.
https://www.khanacademy.org/

sample python codes for testing and to interact / connect S7300 using snap7

Step 1, learn python.
Step 2, Read the documentation on S7-300 and S7-1200, especially the communication options.
Step 3, Read the documentation on python modules.
Step 4, purchase the appropriate equipment
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Thank you for the reply....all the step 1 to step 4 have been attended to. I need a sample python codes for testing such like Basic Python Code to interact and connect Siemens PLC S7-300 OR s7-1200 using SNAP7

FUMMY said:

Step 1, learn python.
Step 2, Read the documentation on S7-300 and S7-1200, especially the communication options.
Step 3, Read the documentation on python modules.
Step 4, purchase the appropriate equipment
----------------------------------------------------

Thank you for the reply....all the step 1 to step 4 have been attended to. I need a sample python codes for testing such like Basic Python Code to interact and connect Siemens PLC S7-300 OR s7-1200 using SNAP7

Click to expand...

Using that library that I link'd, this looks like an example:

https://github.com/gijzelaerr/python-snap7/blob/master/example/example.py

Basic Python Code to interact and connect Siemens PLC S7-300 OR s7-1200 using SNAP7

Thank you for the sample code. I am completely new on coding....
Please kindly share with me also a sample code in Linux style too
I wanted to know how this is working on Linux.

Python is cross platform. Meaning the code you write will run on Windows, MacOS or Linux.

basic python code to communicate and interact with PLCs

Thank you.

I ran the code and changed the IP to my own but with no result. I ran it, no error but not sure if this is communicating.
please what of if I need to read a data (db), network connections from PLCs that was connected on a network. kindly send a sample code...thank you

Well you can't use the example as is, you'd need to modify it to work with your program, it even says in the comments.

If you back up a directory on the github link I provided there is a "boolean.py" example, maybe it will be easier.

I don't really know anything about Siemens PLC's or snap7. You're going to have to put in some effort yourself. Even if I did, I don't know anything about your specific hardware or application.

FUMMY said:

Thank you.

I ran the code and changed the IP to my own but with no result. I ran it, no error but not sure if this is communicating.

Click to expand...

You need to do some basic testing, that should be obvious, and move on from there. If you still need help, you need to give us the details of your problems and details of your testing. If you can't do it with the hardware sitting in front of you, what makes you think we can help? You have not given us any details.

Here's a little basic troubleshooting advice, which should be obvious, but I'm going to tell you anyway. You don't know if it is communicating. What do you expect to see if it is communicating? Are you getting it? If you think you are getting it, but think it is in error, then make sure that you can't communicate and see if you get the same result. Unplug the Ethernet. Do you get the same result?

MIT Open Courseware has several python coding classes available. Its how got familiar with a higher level language coming from C. Im not an expert at C, but I have spent quite a bit of time writing programs in it, and transitioning to python was easy. Check out the videos here

https://ocw.mit.edu/courses/electri...to-programming-using-python-january-iap-2011/

Basic Python Snap7 install

You are correct "dmroeder" and everyone thank you....Agreed. I need to report the error....
I tried to install using "pip install snap7" ...done!

At the moment...there is an error:

Traceback (most recent call last):
File "test_snap7.py", line 4, in <module>
from db_layouts import rc_if_db_1_layout
ImportError: No module named db_layouts

Like I said before, go back a directory on that github page (here) and start with the one that is called boolean.py, that one looks much simpler. We should start out trying to do the simplest thing possible, then build on it.

And FYI, the error is telling you that it is trying to find the file db_layouts.py, which is in the directory where you got example.py (link'd above).

I give you credit for taking the time to learn Python and although there is nothing wrong with jumping in and trying to figure this out, you should also be working on learning the basics at the same time. If you had went through that Learn Python link that I provided above (or any other class/book), this error would have been more obvious.

That being said, start off with the simple example and we'll go from there. We could probably even strip some stuff out of boolean.py to make it even simpler. Looking at that file, maybe start with this?

import snap7

plc = snap7.client.Client()
plc.connect('192.168.200.24', 0, 3)

# In this example boolean in DB 31 at byte 120 and bit 5 is changed. = 120.5
reading = plc.db_read(31, 120, 1) # read 1 byte from db 31 staring from byte 120
print reading
plc.disconnect()

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Someone that knows snap7 better than myself might be able to advise you on the parameters that are in the read function.