While working on an article series on the Siemens S7 PLC supported protocols and a deep-dive in the security settings of these, I was curious about the Siemens S7-WebAPI protocol and instead of guessing, I built a driver for it ... What I like about it: It's HTTPS fully authenticated and the full permission schema of the S7 applies to it.
You can for example have a read-only user, which for OPC-UA, S7 or S7+ I am not able to do.
It's as far as I can tell at least equally secure to OPC-UA, a lot more secure than S7 and S7+, it's on board every S7 PLC that supports TLS secure S7+ (TIA Portal Version V17 and CPU Firmware-Version V2.9 (S7-1500) or V4.5 (S7-1200)). And it's on there for free.
So I've built a fully blown driver around this .... would this be interesting for anyone here to have as an Ignition module?
It would be very interesting to see how your driver behaves with 30k+ tags (maybe some benchmarks?).
I still use the classic Ignition S7 driver today and I've never had any problems with 30000+ tags on my system (most of them are in 1s tag groups)...
In my experience, speed & security don't go together very well...
Well ... 30000+ tags I would probably need a few days creating them on my test-bench
I do think for super high volume none of the OPC-UA / WebAPI approches are good ... I would even think that S7+ would be overloaded quite quickly ... S7 is the work-beast for super high throughput, but also without any form of security.
So I guess it's always a tradeoff ... security costs performance ... however I would expect the WebAPI to perform better than the OPC-UA interface as the Server implementation must be a lot simpler and simpler means less to do for the CPU.
I wrote the driver in order to know what this interface can and can't do ... To me it sounds like a sensible tradeoff between security and performance. And it being on the PLC for free without needing to buy an expensive license for OPC-UA makes me like it even more
S7+ is pretty much a mess ... Siemens completely fu**ed that up in my opinion. You can even see TIA using it in very hacky ways when it's talking to a real device using it.
