Question about analog control SSR

[artooks]

Hi Everyone,

I have been reading about SSR controls, but I do not seem to find the what I am looking for so I wanted to ask, for the last 2 weeks, me and my friend are building a controller, by the way my friend is quite knowledgable about circuits and diagrams which helped me a lot, he is also very good at programming micro controllers, anyway, what we built is an element controller with an SSR, and he specifically built a circuit which triggers the SSR on and off. This has an oled where I can see at what percentage I want the element to be on and off and he programmed it for a total of 100 sec for each period and this is divided into 4 sections each at 25 sec so if I bring the digital pot to %50 that for every 25 second it stays on for 12.5 sec and 12.5 sec off, because he says that this SSR can only work by triggering 5 volts where brings my question in the forum I mainly see an SSR and a analog potentiometer hooked up to the SSR so as far as I know SSR only works on and off is this true so if I bring the the pot half way does it stay on and off %50 or behaves more like a dimmer, I am trying to understand the difference between an analog and numeric potentiometer can someone please explain in simple terms. Because my friend says this analog pot cannot work like this I showed him "SD's" element controller, so I am a little bit confused and want to clarify this, thanks.