Connecting multiple sensors with one probe signal

I have a chinese 6040 CNC which has only one probe input. I want to use this probe input for three sensors.
1. A 3D sensor such as TP06 available from aliexpress. This is an active sensor. This is for edge finding.
2. A Z axis tool sensor also from aliexpress. This I think is a passive sensor.
3. A simple normally open passive probe that I use when milling PCB's. This probe is used to measure height variations on the surface of a cooper board before milling. 

Before trying out my own simple circuit to combine all these sensors to give one probe output, I wanted check with the community to understand if there are any suggestions/tips or ready-made solutions available that can be used in this situation. I also noticed that there are significant price differences in these sensors based on whether it is NC or NO.

Thanks
S

 

Assuming your CNC uses a parallel port interface, you have 5 input pins. You can connect each sensor to one pin, then with a MUX multiplexing function in your HAL file and some digital outputs on the code, select the correct pin to read with the probe input signal each time. This is how I manage 3 signals on my machine:

You can also create some M code with bash commands that connect and disconnect the HAL pins before the probing. Either way make sure to select the correct pin to read before executing the probing routine or you will crash.

If you don't have enough free input pins because you have 3 used for homing the axis, you could tie up those 3 in one and program a secuence for the homing routine.

As you said is also possible to phisically connect the 3 inputs in a circuit. In that case just make sure that the inputs you are not using don't get activated while probing with the other one.