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Endstop Question - Possible Problem

Posted by Rick 
Endstop Question - Possible Problem
December 09, 2008 12:36PM
This is an odd one. My Endstops are attached to the Stepper Driver Boards, each board is powered up and grounded to the power supply chassis, but not connected to the Arduino. The Stepper Driver LEDs light up, no LEDs on the Endstops are lit, all is right with the world. I block...say...the X min Endstop, that LED lights up...everything is still good. I connect the Stepper Driver Boards to the Arduino, power up the boards but leave the power off to the Arduino (USB not connected to a computer). The Arduino is also grounded to the Power Supply chassis. Everything *appears* to be ok. Stepper LEDs burning bright, Endstop LEDs dark and peaceful...until I block...say...*any* Endstop. The blocked Endstop LED lights up bright...and all of the other Endstop LEDs also light up. Not bright, mind you, but they come on dimly.

I've been going over possible issues in my head today. Didn't have the presense of mind to check for voltage at the Endstops last night. Could this be a grounding issue? Could I be inducing Voltage as I have the three wires to each Endstop twisted together back to the Stepper Board (just the three wire for one Endstop not all six sets of Endstop wiring)? Just tossing out ideas...any other troubleshooting tips would be much appreciated! Thanks in advance!


- Rick

A chicken has a head the size of a walnut. Yet, even it has the sense to come in out of the rain.
Re: Endstop Question - Possible Problem
December 09, 2008 01:13PM
I think it is because your Arduino is not powered. You should not feed signals into an unpowered chip because inputs should never go higher than VCC. ESD protection diodes will turn on letting current flow from one opto to another.

If you power up the Arduino I think all will be well.


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Re: Endstop Question - Possible Problem
December 09, 2008 01:18PM
Good to know. I'll check it when I get home. Thanks!


- Rick

A chicken has a head the size of a walnut. Yet, even it has the sense to come in out of the rain.
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