Siemens is now allowing more ways to communicatie with S7-1500

Siemens has released the "S7 plus comm" protocol as far as I can tell but you have to request the information at siemens.

This enables communication to datablocks in an S7-1500 that are set in optimized access mode. this means that data in a PLC can be accessed through symbolic means instead of absolute adressing. also PLC browsing for tags is supported in this.

Any chance this will be implemented ? It could be a gamechanger to see more widespread adoption of ignition in Europe.

OPC-UA server in the S7-1500 is not a decent alternative, as the server restarts at almost every change you make in the PLC. thus breaking connections with scada. if you have this all day at a working plant you will get allot of people angry at you

AFAIK this information is not available to anybody outside of Siemens, requested or not.

There are some third party libraries that have reverse engineered and implemented it and I'll be taking a look at one of them sometime next year to see if it's a good fit for a rewrite or new Siemens driver for Ignition but it's too soon to commit to anything other than that.

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What kind of changes lead to a restart? Is it just that the cycle is too long before the OPC UA server is available and Ignition has reconnected? I would expect that S7 communications are disrupted during whatever these changes are, too.

Basically if any symbol or even its comment are changed and then downloaded. the entire OPC-UA server restarts, it takes long enough for operators to notice, if you have to do this several times a day, people will get irritated.

Its a small improvement for the current firmware. before it just restarted with every download to the PLC.

Regular S7 communication is not interrupted

You are right that the server restarts on any download that affects items exposed to the OPC UA server, such as tags, DBs, and even the comments of those. Much better than in the past where it would restart on any download, even a simple code change.

I have found that the restart time can be drastically reduced by the following:

  • Limiting the number of subscriptions, by reading structs instead of individual nodes. Discussed many times on the forum.
  • Limiting the number of nodes exposed. Untick accessible by HMI/OPC UA on anything not applicable. Everything is enabled by default.
  • Giving the controller a minimum cyclic OB cycle time greater than actual execution time and allowing a higher communication load, such as 50%
  • Batch changes and download fewer times :yum:

Even with its issues, I think the OPC UA server is the best option.

Hopefully one day in a future firmware version this will not happen anymore. The OPC UA server has improved drastically over the few years I've used it.

Reading structs instead of single tags is cumbersome and causes allot of extra load in ignition itself due tot he high number of expressions and reference tags I would require. its not practical.

Running everything in a cyclic OB is not an option in the types of projects I do