Using PID with SSR to control temperature

I have a ramp and soak PID temperature controller and connect it to an SSR, following general instruction. While observing the operation, I am kind confused. A PID controller should change the power out put based on the feedback from the sensor, instead of turning on or off the power to the heater, however, an SSR is an on/off device, and I can see the LED on the SSR blinks. So how should I understand the PID control through a SSR? Is that a on/off controller or a PID controller? thanks.

PID really needs a proportional output but SSD isn't that. You can still use PID though. Use the output to tell you what proportion of a time window the SSD should be on.

Hi @wildbill
what is SSD?
SSR Solid state relay.
SSD solid state devices?

RV mineirin

That's a solid state typo. May even have been Autocorrect, but I suspect not!