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Multiple WIFI Hubs

Posted: Sun Nov 20, 2022 10:45 pm
by scsm
I'm working on a proof of concept am wondering how architecturally it could be achieved. The idea is to have multiple VINT Hubs (HUB5000) and connect them to a "central" solid-state PC (Win 10 or 11).

The central PC would then process some data with a custom cloud-based solution (outside the scope of this discussion).

If possible, we'd like to avoid have a 1-1 ratio between HUB5000 and PCs.

This would be a kind of hub and spoke architecture. It is a dusty environment.

Re: Multiple WIFI Hubs

Posted: Mon Nov 21, 2022 9:03 am
by mparadis
A single PC can connect to any number of WIFI hubs on the same network. In your code, you'd simply enable network discovery and then you can remotely open the channels of hubs, using serial number and hub port to specify what channel is being opened. You can read more about opening channels remotely over the network here.

Re: Multiple WIFI Hubs

Posted: Mon Nov 21, 2022 6:55 pm
by scsm
Thanks for the network server link. I notice that this seems to be more for connecting multiple PCs (and/or Phidget SBCs).

I'm hoping to have a central PC (network server if you like) and connect that to say 10 HUB5000s without having other PCs in the solution. As this is a data collection project, I'm concerned about how long it would take to connect to (over WIFI) check state of ports (like is a switch true or an input voltage high) and then check the next hub.

Due to timing of the above, would we miss data like switch on/off events? If so, maybe we'd need an ethernet wired solution with everything connected to the same ethernet switch. With 100Mb/1Gb ethernet and your HUB5000s I'm assuming we could get the handshake process down to less 1ms. Just not sure what that look like with multiple Hubs connected over WIFI.

WIFI would be preferable if it could be made robust enough. We have other projects planned but getting this one working will be a bit of a proof of concept for the others.

Thoughts?

Re: Multiple WIFI Hubs

Posted: Tue Nov 22, 2022 9:16 am
by mparadis
Even though that page describes connecting multiple PCs, the same programming principles apply for a system with 1 PC and many HUB5000s (After all, HUB5000 is essentially a stripped-down Linux computer).

As far as timing goes, what kind of response time do you require? In the realm of milliseconds, or seconds? In any case, you don't have to worry about missing events entirely- as long as the network doesn't go down completely, you'll still receive all of the events sent out by the Phidget.

Ethernet is definitely more stable than Wifi for this kind of system, but if you write your program to be robust against momentary wifi outages, (e.g. saving variables, having attach/detach handlers for your Phidget objects, etc) then you should have no problems on Wifi.