Robo3D R2 IR Probe

[jay_s_uk]

I'm currently converting a robo r2 from its 8bit board to a duet 2 wifi.
One of the items it has fitted that I'd like to retain is the IR Probe.
Its a copy of dc42's ir probe.
I have it connected via the zprobe port and my config.g says

M558 P2 C"zprobe.in" H5 F120 T6000

But whether I have it near the bed or away, the value is always dancing between 400 and 550.
I should add that the red light is on all the time

Does anyone have any suggestions?

some photos of the board here
https://www.partsbuilt.com/bed-sensor-r2c2-robo3d/

[jay_s_uk]

Its ok, got it sorted, had it wired wrong.

For reference, the wiring from left to right with the LEDs at the bottom is Voltage, Ground, Signal