Homing with 2 inputs/sensors?

Hi!

i have here a axis which has 2 home sensors.
The first sensor is the reference.
the second is a sensor on the pulley.

how it works? Home to first sensor.. then go back until sensor 2 is active.

i the first sensor works on linuxcnc..then i add the second..
net index-sensor gpio001.... 
inet index-sensor joint...index-enable

but then i get error.. 

cant add i/o pin to index... its already output pin hm2_7192.0.gpio.005.in

in the ini i change the parameter for use index as true.. but this doesnt solve anything.

do i need to add a encoder in the bitfile or what is my failure??

thanks

You cannot connect an output pin to joint.N.index-enable
because joint.N.index-enable pins are bidirectional ("Tri-State")

When index is used for homing, LinuxCNC expects to use encoder
hardware to detect the actual index pin and signal that detection
to LinuxCNC via the joint.N.index-enable pin. joint.N.index-enable
is used as a bidirectional signal, that is, when LinuxCNC detects the
coarse home position, it then sets joint.N.index-enable true. This signals
the hardware to enable index detection. When the index is detected,
the hardware normally does two things: it clears (sets to false)
joint.N.index-enable (signaling LinuxCNC that the index has been detected)
and normally also zeros the position.

Does this joint have encoder feedback or it this an open-loop step/dir system?

If no encoder (and you have an up-to-date LinuxCNC installation) , there is firmware
that supports homing to index in open loop step/dir systems, so instead of connecting
a GPIO pin to joint.N.index-enable you would connect to hm2_7i92.0.stepgen.NN.index-enable
to joint.N.index-enable.