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Messages - stirling

591
General Mach Discussion / Re: Shield grounded at one end only
« on: February 07, 2014, 12:42:42 PM »
Thanks again guys - meanwhile another (related) question: When we talk about noise - we're talking about induced voltages right? Any ideas on what levels we could be talking about? i.e. what sort of voltages can be induced into a screen?

592
General Mach Discussion / Re: Shield grounded at one end only
« on: February 07, 2014, 11:17:05 AM »
I reckon you got it Russ - thanks. Gerry - good point but it's not just PC cables - I have a Hypertherm plasma interface cable right here that is screen-grounded at both ends.

593
General Mach Discussion / Re: Shield grounded at one end only
« on: February 07, 2014, 11:09:44 AM »
F***ing hell - sorry Russ and Gerry - I just managed to delete my last post (which you've just quoted). How do I put it back?

EDIT: Bollocks to it - here it is:  ;D

Thanks guys - interesting stuff.

FWIW - This is what I've picked out of it all

1) If your grounding is spot on then ground BOTH ends of your shield.

2) If your grounding is not spot on then grounding both ends is likely to introduce earth loops so just do one end.

3) but in the real world it's not that easy so if it doesn't work then do something else.

But after all this I'm back at my original question which was why commercial ready made up cables have the shield connected at both ends. I guess it's either that or just one end so the designer tossed a coin and said - two it is

594
VB and the development of wizards / Re: Internal error <SetUserDRO>
« on: February 07, 2014, 06:04:48 AM »
Cool. In that case I suspect your original version (022) would also be fine after a re-install. Anyway - you're up and running so thanks for getting back.

595
General Mach Discussion / Shield grounded at one end only
« on: February 07, 2014, 05:07:48 AM »
In every off the shelf parallel and serial cable I've looked at, both end shells are connected via the shield. I've just double checked my PC and printer and was not too surprised to find that the port receptacles on BOTH were connected to their respective chassis which of course in turn are both grounded. So it seems that off the shelf kit does not follow this ground shield at one end only philosophy.

And yet - when I look it up on tinternet - there it is all over the place - ground shield on signal wires at one end only....

Anyone care to shed some light/wisdom/knowledge/thoughts on this?

EDIT: Just to be clear, I understand the logic behind the one-end-only. My question is why doesn't this appear to be the case in "off the shelf" kit.

596
General Mach Discussion / Re: Custom M Code
« on: February 06, 2014, 10:43:08 AM »
I am currently running the desktop computer standalone (not connected to the CNC machine’s breakout board) to eliminate other potential issues; so I am looking for voltage with a multimeter at the parallel port on the back of the computer directly.

Have you installed the parallel port driver?

597
VB and the development of wizards / Re: Internal error <SetUserDRO>
« on: February 06, 2014, 06:13:31 AM »
Best I can suggest is you try a re-install of Mach - maybe ENABLE40.DLL got corrupted but that's clutching at straws. I'm on the same Mach version and XP.

598
VB and the development of wizards / Re: Internal error <SetUserDRO>
« on: February 06, 2014, 05:47:26 AM »
try taking out the explicit typing of A and Y i.e. remove the two DIMs also remove the call to getUserDRO as it's not doing anything at the moment.

599
VB and the development of wizards / Re: Internal error <SetUserDRO>
« on: February 06, 2014, 05:28:21 AM »
Works fine here under XP but usually this CB "internal error" is down to some subtle syntax error. According to VB syntax a procedure call shouldn't have () unless it's called via the CALL keyword. Sometimes it works out ok and sometimes it doesn't. You could try changing line 9 to:

SetUserDRO Y, A

or if you want the parentheses

Call SetUserDRO(Y, A)

Also it's always a good idea to assign explicit real numbers to real variables i.e.

A = 1234.0

600
SmoothStepper USB / Re: SYIL UK + ESS = OMG
« on: January 30, 2014, 09:08:14 AM »
Yep - rip off Britain. i read earlier this month that the Chinese were complaining about our import duty and that it was harming our economy.
So our import duty lessens the amount of sh1te sorry - stuff - that we import from China and therefore the amount of Sterling that leaves the UK and ends up in China is less and that harms OUR economy?  ;D ;D ;D Nice try China!