Re: [CAD_CAM_EDM_DRO] limit/home switches

Great - thanks to all that answered my questions about the switch hookups!
Hopefully I'll be able to report on an EMC/Gecko BP S1 CNC retrofit soon!

Thanks again,

Matt King

-----Original Message-----
From: Jon Elson <elson@...>
To: CAD_CAM_EDM_DRO@yahoogroups.com <CAD_CAM_EDM_DRO@yahoogroups.com>
Date: Wednesday, September 19, 2001 12:41 AM
Subject: Re: [CAD_CAM_EDM_DRO] limit/home switches

>Matthew King wrote:
>
>> Question for you EMC guys - do the various switches need to be

opto-isolated

>> from the parallel port, or can the simply be hooked directly to their
>> respective pins?
>
>You can do it directly. there is some safety for the computer to
>be isolated from the switches. If cables were to get caught on a
>sharp edge and cut, stepper or servo motor power could get crossed
>with the limit switch circuit. if it is not optoisolated, a complete new
>computer (power supply, motherboard, memory, CPU chip, disk drives,
>etc. is a possibility) might be needed. I did see someone do this
>on an old 16-bit minicomputer, smoke, bits of chips flying around
>inside the cabinet, etc.
>
>> Does the parallel send/receive 12 or 5 volt signals?
>
>5 V signals only.
>
>>
>> If 12v, can one power the switches from a seperate power supply and hook
>> them to the individual pins, i.e. pin 10 for the limit switch? I can get

5v

>> from the same power supply easily enough, assuming the switches already

on

>> my mill (series one cnc) are 5v.
>
>Yes, you could do it this way, with the 5V power supply.
>
>Jon
>
>
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