Help building a counting circuit with circuit using LM311

Hi, I'm building a circuit that uses an Infrared LED that sends a signal to a receiver. I want that , when the wave is interrupted, it will generate a signal that will be sent to a CPLD that will do a count. Basically, every time the LED is interrupted the CPLD will do a count. The issue is that I've been told that since the LEd works with analog signals the CPLD won't detect the "low" but it does detect the "high" so I used a LM311 to fix the issue but it isn't working. We put a reference voltage in the inverting pin, the Led detector output in the non inverting pin but the output isn't as it should be.

Any help?

Circuit diagram?

I'll post it asap.