We manufacture a small PLC that is powered by 24 volts and we use a small isolated DC-DC converter to provide power to the microcontroller. Since now the microcontroller is in an isolated power domain we have to use digital isolators between the microcontroller IOs and the external IO (24 volts). This introduces extra cost (isolated DC-DC, digital isolators, etc). I have been wondering what problems we would have if we just used a simple 24V to 5V regulator and forgot all the isolation stuff, especially concerning noise and ground loop type problems. Would we have a less reliable system?