41 Tools

There's a number of tools available which reverse-engineered the protocol:

NI Example Programs

S7 PLC TCP/IP Protocol Reference Example

Uses plain TCP/IP

(+) Free
(+) Runs on all platforms

As the original project seems abandoned, we copied the code originally published by MarcoPolo5 from the NI Code Exchange to our S7COM open-source repository where we host the latest versions and more information on the implementation.

Snap7

http://snap7.sourceforge.net

Communication library for interfacing your C#/Pascal/ LabVIEW/C++ programs with S7 PLC.
Supported CPU i386/x86_64, ARM/ARM64, Sun Sparc, Mips
Supported Windows (from NT 4.0 up to Windows 10), Linux, BSD, Oracle Solaris 11, Apple OSX
Supported C/C++,Pascal,Phyton,Node.js,.NET/Mono(C#VB.NET)
Implemented Client, Server ,Partner objects
Fully scalable (tested from Raspberry to Blade Server HC10)

(+) Free
(-) Library does not compile for Phar-Lap / VxWorks

LibNoDave

http://libnodave.sourceforge.net

Free library to communicate to Siemens S7 PLCs.
Supported programming languages: C,C++,C#,Delphi,Pascal,Perl,VB(A)
Supported PLCs: S7-200, 300, 400

(+) Free
(-) Library does not compile for Phar-Lap / VxWorks

DataAhead SP7

https://dataahead.de/en/shop/sp7/

VIPM package
LabVIEW® 2011 or newer
S7-200, -300, -400, -1200 or -1500 with integrated Ethernet interface
Uses plain TCP/IP communication

(-) Paid tool
(+) Runs on all platforms
(-) Without valid license, code is not executable