Problem with Z limit switch when trying to set up machine to Home

[LarryM]

Check this these threads:

Using Grbl - Direct Communication

Direct access to grbl. You can interact with grbl directly to isolate problems at the low level. To do so, you need to use a terminal type program to issue commands and get responses from the serial port that has the Arduino attached. Some of the programs are HyperTerminal, Putty, UGS (limited access), and the Serial Monitor in the Arduino IDE, among others. Make sure that you have the correct settings for the program that you use. The COM port where the Arduino is attached should have the …

[Guide] Using Grbl to debug your homing switches

If you are having difficulties with your homing switches you can do a quick test with Grbl to see what the state of the homing switches is from Grbl’s point of view. NOTE: In order to use this procedure you need to have grbl Version 0.9j or later installed on your Arduino. To do so, you use the Grbl status immediate command ? (question mark). This command asks Grbl for its current value of some of its state information. For the purpose of this article we are interested in the homing switch stat…