Wanted to get thoughts on how well the technique of using transmission.publish value change per tag is going to scale? We have a large MES initative which cannot consume data via SpB, only plain MQTT, and it is questionable if they can consume SpB via JSON. (Protobus decode still neede for JSON?)
OPC-UA is an option as well but I want to leave that at a last resort as I feel using MQTT broker is more industry 4.0 but do not want to force an MQTT broker if OPC-UA is going to be more reliable.
in terms of scaling, what is the limit to have this type of scripting until 'critical mass' has been reached... 1000 tags changing at 1 sec? I don't think this is the case but does Ignition spawn a new process thread for each script that has to be open/close and creates memory leaks --- or is this type of scripting just as reliable as the source of the tag (assuming OPC), being rarely a doubt Ignition would miss an OPC device poll
Tag value events and alarm events run in small thread pool (default is three threads). So, no, time consuming scripts will not scale. But there are numerous discussions of alternatives and offloading techniques. To get you started:
To get around a client (MES) not being able to decode Protobuf, we could use the JSON data format option? Then it's a matter of the client doing JSON parsing to read the data and we get all the benefits of using the built-in MQTT transmission functionality. I'm not sure what exactly what we're losing dropping the Protobuf format.
Larger payloads, mostly. Less efficient.
How many tags do you think you're going to have in the end? I'm not sure why you wrote OPC UA off so soon.
ha! I watch too many YouTube videos telling me how great MQTT is.
Adding MQTT transmission w/ JSON + distributor module to the tech stack, then having the clients parse the JSON seems a lot more work then simply using OPC-UA which our MES client is already familiar.
The amount of tags could go to almost none to maybe as much as 2,000 tags...this effort is for an enterprise architecture template to roll out to other sites.Then I guess it comes down to the whole MQTT vs OPC-UA debate which can be a seperate thead in and of itself.