LECPython module for PLC

This project have been tested on Windows 11 Pro.

The Python module need to have Net 8 runtime installed.

I have testing a new Python module: LECPython to use for Siemens LOGO. In the document of Siemens LSC we could find that LOGO support 2 different protocols. S7 communication and Modbus Tcp. And if I remember correctly the S7 communication is based on S7-200.

Question: Does S7-200 and S7-200SMART use different S7 communication. (Is that true?)

Documentation could be find here: LECPython | docfx (lecpserver.com)

Its based on C# programming language. (ex. S7Net)

After some debugging in Python I was able to configure it to work with LOGO.

So I share it here, maybe it would be useful. Python 3.12 have been used.

from LECPython import LECPython

from time import sleep

# import inspect

lecp = LECPython()

# res = lecp.SiemensPPIOverTcpConnection("192.168.0.2", 102, 1, "CDAB", True, 2000)

res = lecp.SiemensS7NetConnection("S200SMART", "192.168.0.2", 102, 0, 0, "CDAB", True, 2000)

# res = lecp.ModbusTcpNetConnection("192.168.0.177", 502, 1, "CDAB", True, 2000)

# res = lecp.SiemensFetchWriteNetConnection("192.168.0.2", 102, "CDAB", True, 2000)

if res["IsSuccess"]:

plc = res["Content"]

print("Connection success")

else:

print("Connection error")

## debugging

# frame = inspect.currentframe()

# print(inspect.getargvalues(frame))

# Read memory flag M1

r = lecp.ReadNodeValues(plc, "V1104.0", "bool", 1)

print("M1: ", r["Content"])

sleep(1)

# Write memory flag M1

lecp.WriteNodeValues(plc, "V1104.0", "bool", [True])

r = lecp.ReadNodeValues(plc, "V1104.0", "bool", 1)

print("M1: ", r["Content"])

sleep(1)

lecp.WriteNodeValues(plc, "V1104.0", "bool", [False])

r = lecp.ReadNodeValues(plc, "V1104.0", "bool", 1)

print("M1: ", r["Content"])

sleep(1)

r = lecp.ReadNodeValues(plc, "V0.0", "bool", 1)

print("NI1: ", r["Content"])

sleep(1)

lecp.WriteNodeValues(plc, "V0.0", "bool", [True])

r = lecp.ReadNodeValues(plc, "V0.0", "bool", 1)

print("NI1: ", r["Content"])

sleep(1)

lecp.WriteNodeValues(plc, "V0.0", "bool", [False])

r = lecp.ReadNodeValues(plc, "V0.0", "bool", 1)

print("NI1: ", r["Content"])

Hi FredrikS7

Both S7-200 and S7-200SMART use the same S7 communication protocol. However, S7-200SMART has enhanced features and capabilities compared to S7-200.

For further details, you can check this FAQ:

How do you configure an S7 connection for data communication between an S7-200 and an S7-300 or S7-400 on the Industrial Ethernet?

Hope this helps!

Hi JimHalper

When I asked that question I discover that S7Net Framework that is used in LECPython module have different configuration for S7-200 and S7-200 SMART. I later discover that I could use other configuration as S7-300, 400, 1200 and 1500. All this would work with LOGO.

I did try to locate the part in the source code of S7Net that is programmed in c# to understand the reason of it. It maybe could be that I didn't use TSAP and thats why the other worked but not S7-200. The documentation of LECPython is not so clear if TSAP is used for S7-200.

On other hand LECPython use foreign function library (programmed in c#) and I do not have access to the source code to do a more deeply research why S7-200 do not work. It could be that my configuration is missing something.

Thanks

Thank you very much for using LECPython. First, I need to clarify that the communication protocols of Siemens S200 and S200Smart are different from those of other models. In their protocols, "LocalTSAP" and "DestTSAP" are used to define the communication data header. After reviewing the previous documentation, I found that this part was not explained in detail. I have now added the following explanation to the latest documentation:

LECPython Document

When the type is set to S300 or S400, the input parameters "rack_or_localTSAP" and "slot_or_destTSAP" will correspond to the device's "rack" and "slot" settings, respectively. However, when the type is set to S200 or S200SMART, these input parameters will correspond to the "localTSAP" and "destTSAP" settings.

I have also updated LECPython to v 1.2.3.6 Please use the latest version for setting "rack_or_localTSAP" and "slot_or_destTSAP".

Please feel free to contact me if you have any questions.

[Snip...]

github:https://github.com/xeden3/LECPython

Below is the C# code related to localTSAP and destTSAP in S200 and S200Smart.