That would be super awesome :-) Chris
Von: Sebastian Rühl <[email protected]> Datum: Samstag, 9. Mai 2026 um 12:06 An: [email protected] <[email protected]> Betreff: Re: [SPI3] New S7 driver (Merged S7 and S7-light) Hey Chris, awesome work. Sure I can look into the plc4go part. Should I fix that on your branch? - Sebastian On 2026/05/09 08:27:52 Christofer Dutz wrote: > Hi all, > > After a week of 16 hour shifts I’m happy to announce that probably the > largest beast has landed in the SPI3 branch. > It’s generally a complete rewrite of the S7 driver. > > What took a bit of time with this, was that I needed to understand what Cesar > did to make the S7 driver different. > Turns out the main points were: > > * > Support for Cyclic Subscriptions on S7-300 and 400 PLCs > * > Support for subscribing to Alarms/Events on S7-300 and 400 PLCs > * > Support for S7H (Redundancy) where you establish two simultaneous connections > it transparently executes commands via the primary, if a failure of the > primary connection is detected, it switches to the backup connection (As the > old driver didn’t handle the special case of subscriptions on these setups, I > actively defined that as unsupported when using a S7H connection. > > > The interesting thing that I found out when testing: As my S7-300 had a > secondary communication board, I wanted to use that for testing, however it > turns out my communication board is a „light“ version, that doesn’t support > S7 protocol. So, I tried two S7-1500 that have the same memory layout, and it > worked flawlessly. So possibly we should advertise this feature a bit more as > you seem to be able to use I with any type of S7 PLC. > > As this was also the first driver that I know of, that really supports the > „Event“ type subscriptions. I realized that our browse-items only had as > „supportsSubscriptions()“. However, the one type of tag only supports EVENT > and others support only CYCLIC, so I extended the API module to add a method > where users can list the supported types of subscriptions. The > „isSubscriptionSupported()“ was changed to checking if the other is an empty > list. > > @Cesar Garcia<mailto:[email protected]> It would be super awesome, if > you could give my changes a test against the hardware you built these > features for. I did my best to try and test things here, but you can’t beat > the real thing. I also hope you are not too confused about a completely new > driver. The architecturally interesting major differences are, that this > driver no longer implements the TPKT and COTP layer. This is now all handled > by the new COTP Transport (I learned there’s a whole zoo of Siemens protocols > for various types of device, which use COTP. Also does it handle the breaking > point between COTP and S7 a lot nicer and should make the overall driver a > lot simpler. The S7H stuff is handled transparently by s secondary > S7HCotpConnection wich complements the default S7CotpConnection. So all of > the handling of this is incapsulated in the S7HCotpConnection. > > I’ve also used some time to adjust the PLC4C, PLC4Go, PLC4Py and PLC4Net to > work with my changes in the mspec (String encodings are named „UTF8“ and not > „UTF-8“ … same applies to all the other string encoding names) … also is the > byteOrder property no longer an enum, but a string (In order to support these > super odd byte-orders in drivers like Modbus LITTLE_ENDIAN_BYTE_SWAP etc.). > In the testsuite XMLs the two properties driverName and languageFlavor -> > driver-name and language-flavor … All other languages pass, however I could > use a bit of help with PLC4GO … so Sebastian … if you wanna earn a few beers > … could you please have a look? > > So … that should probably be it for now …. Gee what a week … I think I should > probably crank down my shift times … 16 hours a day isn’t healthy. > > > Chris >
