Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: rfhall50 on April 30, 2020, 12:57:49 PM

Title: Sorry to ask, but ... LIMIT SWITCHES
Post by: rfhall50 on April 30, 2020, 12:57:49 PM
I hate to ask a really ROOKIE question, but ...

Are limit switches strickly a break in CONTINUITY, or do you need to supply voltage?

Had a problem testing the Estop. Can't seem to get it to work using a break in continuity only.  I understand N/C vs. N/O.  I have tried GROUND to ESTOP connection using only a break in continuity. Getting a direct answer to the question above has been difficult.  (Broke a coupler because it wasn't working).

I am using a SainSmart 5 Axis BOB.

Thanks in advance.

Bob
Title: Re: Sorry to ask, but ... LIMIT SWITCHES
Post by: joeaverage on April 30, 2020, 04:52:51 PM
Hi,

Quote
Are limit switches strickly a break in CONTINUITY, or do you need to supply voltage?

No, they are not strictly NC, although it is common.

On the Config/Ports&Pins/InputSignals page you enable each of the limit switches and also nominate whether the signal
is active high or active low.

It was very common to use six snap action microswitches NC contacts and all wired in series. Therefore any wire break (fault) or any
switch activation (to open circuit, ie limit event) would cause a limit event and the machine would Estop.

Craig
Title: Re: Sorry to ask, but ... LIMIT SWITCHES
Post by: rfhall50 on April 30, 2020, 09:16:44 PM
Thank you for your quick response.  Based on what you told me, plus a graphic I found, I think I need to recheck my setup.  Thanks again.

Bobby