Hi im currently building an application to control over 200 device in a building. Originally i want to use an arduino and bunch of relays to control them. After asking some questions and such in this forum, people suggest me to use a PLC instead(concerning safety and such). My new problem is that, i dont really understand how PLC works for a lot of devices, what do i do if i want to control 200 relays with a PLC? most PLC only got 8-16 Relay output? how can i extend it?
Im not asking a recommendation on which product to buy and such etc (as i know it against the sites rule), im just asking on a appropriate approach to my application. Thx for the comment and replies !