Get different datasets at different frequencies from one PLC

Hello community,

the title says it. I'm using node-red-contrib-s7 to connect to my s7-1500. I have one rather small dataset (only a bunch of booleans) that I'd like to receive at a relatively high frequency and one much larger set that I only need to receive every couple of minutes. Right now I'm trying to figure out the most elegant way to do this. I just started using node-red so please bare with me if my question is too stupid.

My first intuition was to not request unnecessary data. To this end, I tried to create two connections to the same PLC - but that resulted in errors and a somewhat unstable node-red. Provided I have not done something wrong, I don't suppose that this is going to be the way to go.

I also played around with interval-based inject-nodes in conjunction with the "s7 control"-node, but since this node triggers all "s7 in"-nodes with the same plc connection its not really helpful either.

My last idea was to just request ALL the data at the higher frequency and use some javascript to split it up and only use the big chunk when needed. But this means constantly sending loads of unncessary data which I am not the biggest fan of.

Is there a better, more elegant solution which I haven't thought of so far? Maybe sending huge loads of data isn't that bad anyway? I'd appreciate any sort of input. Thank you in advance.

 Thank you very much for your answer.

bergmanu

1. I have tried two different connections with two different variables and cycle times and got no problems so far (see attached flow). What was your problem? I assume you tried some more than 2 variables?

I got it to work for now using two connections to the same plc - not sure why and how, but I'll take it. Maybe I misconfigured something before even though I checked many times. There are still little hickups sometimes when the "s7-in"-nodes lose connection for a moment, but that's only temporarily and no severe crashes like before. Unfortunetly I didn't save the error messages (that was dumb) and since things appear to be working for the moment I'm kinda reluctant to stir the pot.