Step7 Openess?

1. It is not possible as far as I know; unless you are usingM7 or CPU614 (good luck).
Using WinLC (RTX) you can come closerusing the ODK.S7 is not that open as it was S5. Thereason behind this is that Siemens is trying to make 80% profit by selling software and only 20% hardware. To get there you will document only the layer necessary to understand and use their software (STEP7 and co)and not a bit more.

2. S7 protocol is not documented (see above reasons) but you can figure out most of the services using Ethernet analyzers and practice with S7API examples. Plus if you know how to enable tracing you will get some cluesfrom these trace files also.
Reading SZL from the PLC is based on S7 protocol Msg_Type 0x7, Service 0x0, Function-Code 0x4401.
Btw don't be surprised when you discover lot's more SZLs then are documented or that can be accessed using SFC51 [;)]

3. You can also use a batch file (SCL compile control file)to compile SCL source files.

Dec