Inventables E Stop Button not killing power.

[jrsteensen]

Step one: Isolate the problem. Remove the E-switch and just touch the wires together....the system should run. Disconnect the wires, the system should stop.

[colin]

The wiki page has been fixed.

The 24 volt wire is the one you want interrupted with the eStop. The system stays grounded together and power is removed from the grblShield and the motors.
Warning: If you interrupt the ground line with the eStop the motor current will find it's way back though the USB port to the computer. This is not good on multiple levels. (1) USB is not meant to carry that much current. (2) the power supply ground and the computer ground (the USB ground) may be at different potentials. This risks blowing out any of the PC's USB port, the Arduino's USB port, the TI driver chips, the power supply itself.
Please note in the diagram the "hot" wire is red. The actual wire that came with the kit in Batch #1 is black. We will be updating this to a red wire in the future.

http://www.shapeoko.com/wiki/index.php/Inventables_Electronics#Wiring

Sorry about the confusion! The two of us who were working on that wiki page made an honest mistake and we've learned from it.

[baerwulf]

I noticed this problem too.

I rewired my e-stop to the +24V and ran the ground directly to the terminal on the driver board. It now works as intended. Just make sure you do not get the polarity at the terminals wrong!

It appears that the ground planes of the grblshield and the ardurino are connected, so cutting the ground does not break the circuit, as the motor driving current is sunk through the ardurino and back to the computer / usb hub when the e-stop is activated. This is probably not good for the USB port.