Messages

11

General Mach Discussion / Re: Mdi is not a MODE

« on: November 04, 2016, 01:38:05 PM »

No truer words have ever been spoken Ian.

Hey stranger - where you been? 

Cheers Brett

12

General Mach Discussion / Re: Mdi is not a MODE

« on: November 04, 2016, 05:04:19 AM »

So just learned that if you are in the MDI screen and press the hard cycle/start button (shouldn't be doing that but I did), Mach executes the current program on the main screen.

Out of the box - Mach won't run a program from the MDI screen. Someone has customized it to respond to hard buttons and done it without due care.

I've lost track of the crappy code people have added to Mach without really knowing what they're doing and then blamed Mach for not doing what they want.

13

General Mach Discussion / Re: Backlash...

« on: November 03, 2016, 12:27:35 PM »

Stirling,
You can't leave

That's actually a bit scary...

as in... You can check-out any time you like, But you can never leave!

14

Third party software and hardware support forums. / Re: Parallel port wiring

« on: November 03, 2016, 08:28:48 AM »

You're quite correct that you (always) need current limiting to drive an LED but this is the first time you've mentioned an LED (I've already asked about optos). This is why we need to know what we're dealing with. As I said above, how you go about this completely depends on the type of input we're trying to interface to. The crux is that unlike a parallel port which is (almost certainly) totem-pole, open collectors can't source current they can only sink.

15

VB and the development of wizards / Re: bcd input

« on: November 03, 2016, 08:00:26 AM »

OK - so if you look at the table in your pdf.

If we re-arrange it as per the following:

1) use 1 to mean the input is active and 0 to mean inactive (rather than voltage levels)
2) put it in order of most significant bit to the left rather than least significant

we get:

Code: [Select]


STATION            D   C   B   A

 none              0   0   0   0
   1               0   0   0   1
   2               0   0   1   0
   3               0   0   1   1
   4               0   1   0   0
   5               0   1   0   1
   6               0   1   1   0
   7               0   1   1   1
   8               1   0   0   0


i.e. plain simple 4 digit binary counting where all 0 (inactive) means between stations.

16

General Mach Discussion / Re: Backlash...

« on: November 03, 2016, 07:09:09 AM »

Must have got the wrong end of the stick - sorry. I thought the point of the thread was that you had issues. If you're happy - I'll get back in my box.

17

General Mach Discussion / Re: Backlash...

« on: November 03, 2016, 05:46:38 AM »

I reckon you're trying to make a silk purse out of a sow's ear here Dave. Looking at your test text toolpath you posted elsewhere, some of those moves are an order of magnitude less than your backlash. Is it really sensible to use a 0.2mm engraving bit with thousands of moves of a few 100ths of a mm on a Bridgeport I wonder?

18

Third party software and hardware support forums. / Re: Parallel port wiring

« on: November 03, 2016, 05:40:14 AM »

The current limit resistors was just a thought about not putting 5 volt from a supply that might supply amps into a port that can only handle ma.

You're making the classic mistake of thinking your PS will somehow "push" more current into things than they can "take" - When you apply a voltage across something, the current will be determined by the resistance of that "something" according to Ohms Law. (which here will be milli-amps). Doesn't matter how many amps the supply is capable of supplying as long as it's "enough". i.e. if the connected circuit "draws" 20mA and you have a 100A supply it matters not (apart from wasted money of course).

That said - without knowing about the input config of the drivers. it's not really possible to say the best way to do this. For example, IF your driver inputs are opto-isolated and are driven by SINKING current then you wouldn't need to do anything except attach your open-collector. However if they're opto-isolated and driven by current SOURCING (unlikely), it's a different ball game. If they're NOT opto-isolated then you'll need a 5V supply and a pullup.

19

Third party software and hardware support forums. / Re: Parallel port wiring

« on: November 02, 2016, 11:17:47 AM »

OK - then back to your original questions:

Yes you'll need a 5V supply because (presumably) that's what your drivers logic will need (given they were intended to connect to a PC parallel port). Does the driver box not already have a 5V supply built in that you could tap off?

If the controller is open collector then you'll need pullup resistors because when the transistor is off the open collector output would be floating.

Not sure what you were intending to do with current limiting resistors - can you expand a little?

20

General Mach Discussion / Re: Backlash...

« on: November 02, 2016, 05:23:37 AM »

FWIW Dave - I can't for the life of me see how BC can co-exist with CV - particularly with lots of V small moves.