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Author Topic: E-STop & Limits Wiring...  (Read 3882 times)

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Offline Davek0974

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E-STop & Limits Wiring...
« on: January 17, 2014, 06:57:13 AM »
Hi all, first question, a bit basic :)

I am building a CNC plasma table and as I have never used CNC before, its a learning curve.

Reading the forums and the manual, I have gained some insight into the wiring methods to use for limits etc, but want to check I have the facts right...

There are only 5 inputs available (1 LPT port),
I can daisy-chain the limit switches (2x, 2y, 1z) and only use 1 input,
The E-Stop is on its own input, or can it be daisy-chained in with the limits?

If I later add THC, I believe it will need 3 inputs (Up, Down, Arc OK)?

In Mach3 I can use the limits as soft-home switches too (with the caveat of making sure the carriage is off the limits before homing)

With the E-stop in the limit chain, this setup will now use all 5 inputs, am I on the right track??


Many thanks

Dave
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: E-STop & Limits Wiring...
« Reply #1 on: January 18, 2014, 05:37:58 AM »
Best to have the E-Stop as a separate input.

Not sure about Plasma, never used it.

You can use the limits as home switches with Mach, that then allows you to utelise soft limits as well.

You can also add a second parallel port if you require more I/O or you could go the external controller route and do away with the parallel port all together.
Hood

Offline Chaoticone

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Re: E-STop & Limits Wiring...
« Reply #2 on: January 18, 2014, 06:36:59 AM »
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline stirling

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Re: E-STop & Limits Wiring...
« Reply #3 on: January 18, 2014, 07:22:38 AM »
or you could go the external controller route and do away with the parallel port all together.

Well this depends. At one time not so long ago the ONLY motion device that fully and correctly supported THC was the parallel port. I have heard anecdotally that the ESS (not USB SS) and some/all (I don't know) of the CSMIO controller(s) now also support THC.

I have had one customer of my THC use it with a CSMIO but not everything was as it should be - unfortunately he decided things were "good enough" so we never got right to the bottom of it what was different between the PP and the CSMIO's THC functionality.

Anyway I contacted CS and Warp9 to try to get some definitive answers but unfortunately neither replied. Well Greg replied to my first email and said the ESS DID support THC but advised against the USB SS but when I posed further detailed questions I didn't get a reply.

So I think you pays your money and you takes your chance with regard to external controllers and THC.

FWIW my THC can be configured to only use 2 inputs - this free's you up 1 to use for IHS. ;)

Offline Davek0974

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Re: E-STop & Limits Wiring...
« Reply #4 on: January 18, 2014, 10:51:39 AM »
Thanks, so I can daisy-chain the limits and use one input, then another input for the E-stop which three inputs free for THC if I go for it.

Screened cables definitely, star grounding and so on.

Will look into 24v control circuit too with opto isolators, never good taking a 5v PC supply line on a round trip of a machine ;)
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Chaoticone

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Re: E-STop & Limits Wiring...
« Reply #5 on: January 18, 2014, 12:00:49 PM »
Quote
Will look into 24v control circuit too with opto isolators, never good taking a 5v PC supply line on a round trip of a machine Wink

Exactly, especially a plasma.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Davek0974

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Re: E-STop & Limits Wiring...
« Reply #6 on: January 18, 2014, 01:11:50 PM »
Regarding the controls circuit, would a 24v loop with the limit switches in it, connected to a small relay which has it's contacts connected to the BOB provide enough isolation?

This would give a relatively high current control loop (more than logic levels) and the relay would be wired fail-safe I.e. energised until a limit switch is hit or the e-stop pressed.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: E-STop & Limits Wiring...
« Reply #7 on: January 18, 2014, 03:01:44 PM »
Yes, I used to use relays before when I used controllers that were 5v I/O, the ones I use now are 24v I/O so no messing with relays and optos etc :)
Hood

Offline Davek0974

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Re: E-STop & Limits Wiring...
« Reply #8 on: January 19, 2014, 04:16:05 AM »
Excellent, I have a lot of small din-rail mount relays I can use.

This would give fairly good noise immunity and also reasonably good voltage isolation as the relays have a fairly high flashover rating from coil to contacts.

I have a steel cabinet to mount the BOB and drivers in, might also strip the PC and mount that inside too, keep it all in its own environment etc.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: E-STop & Limits Wiring...
« Reply #9 on: January 25, 2014, 02:11:30 PM »
Just trying to figure a few settings out, my BOB hS a relay on it for spindle control, which options do I need to set in mach setup so it comes on with the torch-on code??

I'm going to use the bob relay to drive a larger relay for a bit more isolation, this will then drive the plasma cutter.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives