I hooked it up to my Videx 3131 yesterday and it works
The scematic of Videx 3131 looks like this, which is an analog system:
- black and purple wire to connection 1
- blue, red and yellow wire to connection 3
(Yes, the Scematics point out, that connection 3 should be ground but your pics and my vides 3131 also had the red wire connected to 3)
This works for me! I can open the door and can get a notification when the bell rings. But the bell supression feature will not work.