Z homing and port #3 outputs

[fdeporte]

Hi all,

I am running my new MechMatecontrolled by AXBB-E and I have two issues.
- When I switch off my router, a gas spring lift my Z axis until a stop block. At this top position, the limit/home sensor is over. I cannot home my Z axis like that, I have to push down by hand the Z axis, in order to squeeze the gas spring and go down Z axis below the limit / home switch before homing. I dislike this way to do, can you please tell me how can I do before homing ? Must I modify Z axis homing macro to go down below the sensor, overridding it before homing ?
- I have used all the port #2 inputs, I need to use inputs of port #3. Can I use it for limit/home switch ? I have not found how to wire these inputs in the documentation. Can you please explain me how can I wire a PNP limit switch on the port 3 ? Is another breakout board required ? I need only one other input and I haven't still the place to mount it in my enclosure. Can I directly wire on the port #3 pin ?
Thanks a lot, I have send you lot of questions and you still answer me as well as possible.

Best regards,

Fred

[dezsoe]

Hello Fred,

- In UCCNC there's no homing macro, so you cannot change it. When you start the UCCNC then press Override limits then Reset: now you can jog the Z off the sensor and start homing. (In fact, you don't need to jog Z: you can start homing Z. It will come off the sensor, because the program will know that it is already on the home sensor.)
- On port #3 all inputs and outputs are TTL level, but most sensors will not work with only 5 volts. You should connect a proper board. I advise to use a UCSB, which you can connect to the same 24V as the AXBB.

[fdeporte]

Ok, thanks.
So, instead of using port #3 input for limit switch can I use it for probe signal and get back the previous port #2 probe input to wire my limit switch ? Port 3# input is sufficient as is to wire probe signal, no ?
Thanks a lot.

[dezsoe]

If you really know what you're doing, than yes. But there is nothing to save your AXBB if you connect something wrong, that's why I advised to use an isolation board.