Siemens 6ES7315-2EH14-0AB0 Software Version

Got a call out to a customers site tomorrow. They have the above PLC and accompanying wiring diagrams from Nov 2013.

Anyone any idea if you can tell from what it was programmed with at a glance?

We are fully paid up with Siemens software but do anything to avoid using it.

My VM has v13 as we never did anything with 10, 11 or 12 and Step 7 obviously.

I really don't want to spend the evening downloading 10, 11 and 12 if I can help it.

I don't see any attachments, but odds are that it was programmed in Simatic Manager, not TIA Portal. V11-V13 support the newer 300's, but most people still use the older software. Projects can be migrated forwards, but they can't be migrated back.

Well, if you have the source file, eventually as an archive file, then you can see it by the file extension.
v5.5 archive files are usually .zip (but some use .arj).
v11 archive files are called .zap11.
v12 archive files are called .zap12.
v13 archive files are called .zap13.
v14 archive files are called .... you get the idea

Most probably the 315-2PN/DP was programmed with STEP7 v5.5.
Less probable, but not impossible, it was programmed with STEP7 V11-V13.
If you have STEP7 V13, you can migrate it easily if the original program is V11 or V12.
If the original program was made with v5.5, then it has to be migrated, and you may run into that it is not that easy to do, though definitely possible.

Sadly there is no original project, at least none the OEM is willing to let the customer has, hence i'm going in somewhat blind!

Fingers crossed it's the old Step 7

You can upload the program from the PLC, but it will be without comments or symbols.
One thing that you can do if there is a problem is to access the diagnostics buffer for troubleshooting.
Apart from that there is not so much need to go online. Most hardware in S7-300 is backwards compatible so you can replace any old module for the newest version with no need to update the hardware configuration.
I would not fiddle with the uncommented software unless I were absolutely desparate.