Hello, thanks for this amazing OpenPLC project. I want to ask if it's possible to expand raspberry GPIO ports with SONOFF as Slave? If its possible how many SONOFF i can connect to Raspberri ? SONOFF will be connected to same WIFI as raspberry and will be working and communicate "realtime" with raspberri pi with OpenPLC program? Thank you for an answer. 🙂
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You can connect as many slave devices you want. Just keep in mind that too many devices might overwhelm your network. To accommodate more devices you can adjust the polling rate at OpenPLC settings. A smaller number on the polling rate (faster polling) will make OpenPLC query slave devices more often which will require a good network with a lot of bandwidth. If you have multiple devices, try increasing that number. It will make OpenPLC query the devices less often, leaving some gap between the requests
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If you're looking to add many devices, then it's time to start thinking about your system design. You could zone your devices and run two or more OpenPLC devices with ScadaBR provding overall visualisation and HMI control. My setup currently has 3 raspberry Pis running OpenPLC (weather monitoring and garden irrigation, a beer brewing station, and lighting controls (automatic and manual)) and a virtualised ScadaBR instance running on a server with a few other (test and research) VMs. Whilst I probably could run these on one instance of OpenPLC, I have the benefit that when I'm between beer brews, I can take that device offline and perform upgrades, or I can upgrade the weather monitoring without interrupting my lighting controls and (more importantly) my beer brewing.
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