Software Required for Siemens S7-300

I am familiar with the Allen Bradley software required to communicate with the various Allen Bradley PLCs. I have no idea what is required to communicate with a Siemens product and I have no idea where to get a demo. I would like to connect to a S7-300 and go online with it so I can see the ladder logic. What software do I need and where can I get a demo? Also, is it possible to go online and see the ladder logic if I do not have the ladder logic file on my local PC?

Thanks

Exactly what type no of the S7-300 in question ?
Some S7-300 have only MPI, others have Profibus and/or Ethernet.

If it is a CPU with MPI, then STEP7 LITE (https://support.industry.siemens.com/cs/de/en/view/39596695) might be enough for you.
For MPI you also need an adapter. Either Siemens 6GK1571-0BA00-0AA0, or a less expensive 3rd party adapter.

Otherwise you need a full license of either STEP7 v5.5 (aka "Classic") or STEP7 PRO v13 (aka "TIA").

If you dont have the source program, you can still upload it from the CPU (if you have the password, or it is not password protected). The upladed program will be without comments or symbols.

The full STEP7 PRO v13 or v14 is expensive.
There is a cheap trial that can be purchased for approx 30 $ (6ES7822-1AA04-0YA7). It runs for 21 days.

I appreciate the response and the help. I will give it a try but I suspect the oem has the PLC password protected.