Node-Red fast retrieval of variables

[manuel.avitia.v]

I am currently using Node-Red with the Opto22 Provided OPC pac control node, it works great, I am able to retrieve a fairly large table once per second.
I have noticed, specially when running node-red on a non-local instance, that when there is a network issue, and it gets reconnected, data starts lagging, with events where the observed data is minutes behind the real condition.
I am not sure if this is caused by the tcp nature of the request, or if the node itself has a buffer, attempting to retrieve older messages.
The issue is cleared when the node-red is restarted, or a change is deployed.

but my question is regarding the best approach when it comes to retrieving the “latest” status of the variable, in my case, I dont need the older values, I just need the latest “current” value, is the Opto22 node still a good approach? or should I look into a Modbus request instead?

Regards

[torchard]

For high-speed reading (less than 1s scan time) I have gotten really great results with UDP streaming configured via OptoMMP, is that something that would work for your application?

Here are some posts on how I’ve set up UDP streaming with Node-RED:

(Very) fast way to read digital inputs via UDP streaming using ONLY Node-RED

Thanks to a post in an earlier thread by @philip (link) I have been testing UDP streaming of digital channels, but focusing on using just Node-RED, rather than groov Manage and Python. This approach is entirely based around the OptoMMP endpoints for streaming configuration that’s fully explained under “Streaming Configuration–Read/Write” in “Appendix A” of the Opto22 - 1465 OptoMMP Protocol Guide The specific address is 0xF03FFFC0, and uses the 10 32-bit integers that follow to configure diffe…

UDP Streaming an entire RIO module's data

Building off of a project from earlier this year, (Very) fast way to read digital inputs via UDP streaming using ONLY Node-RED, I’ve written some extra code to process floating point values for analog AND digital I/O at the same time. The cool thing is that with all that data you can easily combine the results based on your channel configuration so that an entire groov RIO module can be streamed – regardless of how your RIO is set up! For this example I am streaming all my RIO Learning Center I…

[manuel.avitia.v]

Yes, that would actually work. the only difference is that I would need to read a pac control variable, rather than a digital input, I need to dive a little into the documentation to find out the mapping, worst case scenario I can use a PID loop and read the address from there.
I will post the results, thank you.

[manuel.avitia.v]

Just updating, I ended up using the proposed method, with a few mods, turns out the scratchpad makes the application of this method super simple.

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