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Messages - smurph

1331
Galil / Re: unexplained stop during program
« on: January 30, 2011, 06:23:30 PM »
Steve,

I sent you a new plugin to try.

Steve

1332
The advantage the Ethernet has over USB is purely for the developer.  Once you beat it into submission, the devices perform quite well.  There is nothing wrong with USB.

I use Galil controllers.  http://www.galilmc.com/  The Vital Systems DSPmc also uses Ethernet.  Mesa http://www.mesanet.com/ is prototyping an Ethernet device as we speak and they already have a USB and PCI/PCIe devices.  Smooth Stepper is what I would be using if I was driving steppers.  It flies!  I saw a machine running it and I was super impressed.  Then there is K-Flop too (That one looks nice.  I wish I could see it in action as well.).

My point is that external motion devices are the future.  USB and Ethernet.  There will be plenty to choose from that are within the grasp of the hobbyist.  And once someone converts from the parallel port to one of these devices, they will wonder why they didn't do it sooner.  The speed and smoothness are "unparalleled".  (pun intended.  I could not resist!  :) )

Steve

1333
Yes.  That is exactly how I control a Galil Ethernet controller with Mach.  Typically, you want to have your controller on it's own network.  The simplest most direct way is to connect the Ethernet card in the PC and Ethernet motion device with a crossover cable.  No router or switch required.

But...  If your network is in good shape, meaning that it's functioning properly and not over utilized, then communication from the PC through a switch to the motion device is perfectly acceptable.  I have a 10Mb old school network that I use and it rocks.  The latency is in nanoseconds as compared to milliseconds with USB.

Steve

1334
*Off Topic*I am curious about the USB comment you made, what would they replace it with? SATA? I haven't really been keeping up on the new tech. Im pretty sure my spare computer I run right now(My gaming Comp. died) runs USB 1.0. lol.

I don't know for sure.  It might be PCIe external.  But that is an expensive proposition right now.  It will get cheaper.  And buy the time USB 3.0 is done, there will probably be a new kid on the block anyway.  But don't count Ethernet out.  They have about got the price of an Ethernet interface down close to that of a USB interface.

USB will hang around simply because of the shear number of USB devices out there.  However, I do have some USB devices that don't work with Win 7.

For the end user, USB is very appealing.  Plug and play.

But there are problems with USB that people (motion developers) want to get away from.  Namely latency.  Especially with the Windows OS because USB support was grafted on.  Remember that M$ didn't WANT to support it because it hit the Apple first!  So it is kind of stuck on like a sore thumb in Windows.  The Windows scheduler is what is responsible for initiating the outgoing stream.  By default, a packet is sent every 16ms, if there is data to send and it is less than 64 bytes.  You can trim this down to 2ms with some USB devices.  And you can also do tricks like forcing the packet to 64 bytes.  In short, sending short packets at a high frequency is challenging.  So what developers HAVE to do is some sort of buffering to ensure that data gets to the device in a smooth enough stream with a quantity of data that is large enough to hide the latency. 

Another problem with USB is that it does require a device driver.  (same is true for PCIe and friends) If the maker of the USB chip set stops supporting it and decides not to write a device driver for the OS of the day, then it will run into obsolescence leaving the poor hardware developer hanging.  Ouch.  So something that doesn't require a device driver really looks nice to a hardware developer.  (Ethernet anyone?  :)  )

I believe that low cost Ethernet based motion devices are on the horizon.  (That's a hint!)

Steve

1335
Galil / Re: Gantry homing problem
« on: January 20, 2011, 12:13:23 PM »
Make sure that the "Home slave with master" is not checked in the Mach General Config.

The Galil plugin puts the master/slave axis in gantry mode.  But if Mach sends movement commands to the slave axis, then the movement of the slave axis is doubled!

In the next release, I will handle this case in the code so that no matter how the General Config is setup, it will do the right thing.

But...  as Kenny said, a GalilDebug.txt file would be nice to verify this.

Steve

1336
Like I said...  things change.  The segment of machines that you can even add a parallel port to is growing smaller by the day.  The writing is on the wall.

For Mach, the question is whether to invest the required resources (time and money) into a dying technology.  It will become a business decision that will be quite simple.  And we may already know the answer.

Steve

1337
Wow...  I just read the whole thing.  People saying "It's 20xx and asking where is the 64bit parallel support?  The irony is killing me!  Shouldn't we be saying "It's 20xx and why do we still have a parallel port?"  It's hard to buy a printer with a parallel connection these days!  That was, after all, the mainstream use for a parallel port.

My current PC (over 2 year old now) didn't even come with a parallel port ,nor PS2 mouse and keyboard, not even a serial port.  It only has 1 PCI slot and the rest are PCI express.  DVI video connectors are going away in 2012.  The old VGA db15 connector is going away in 2015.  HDMI is a fleeting moment in time for PCs (to be replaced with DisplayPort).  Even USB almost didn't make it for 3.0.  And I bet 3.0 is the last "version" of USB, although it will hang around for a while.  It was inevitable that the parallel port goes away.

My point is that things change.

The good news is that back in the 80s, you paid $4K for a PC that had a parallel port and these days you spend less than $1K for a PC and an external motion device.

Steve

1338
Oleg,

Can you set your MainPlanner->ExTime to something like 4ms?  1ms may be putting the trajectory planner through too much.  Or dumping that much granular data to your device may be the bottle neck.  I've run some of my plugins at 32ms.  But I had the capability of matching that time slice in the hardware.  The reduced resolution is only noticed at very slow speeds.  You will never notice anything with a time slice of 16ms or lower.  So if 1ms is not a requirement, try some higher values.  The Galil plugin uses 4ms time slices and it flies (ExternalPulseRates @ 12000000).

Steve

1339
Galil / Re: unexplained stop during program
« on: January 13, 2011, 02:52:04 PM »
Steve,

Your machine looks fine.  Heh...  with the exception of the trackball.  :)  I just can't get used to those things!

Steve and Chris,

I'll get you both a new plugin this evening.  I have Steve's email.  So Chris, send me a PM with your email address.

This new plugin is working toward release 4.5.  It's pretty different as far as how it works internally and there may be bugs in it (MPG and homing code related), so I would not suggest running it full time.  But I would like to see if any of you can duplicate the lockup with this new plugin.  If you can duplicate the lockup, then it's a high probability that it's not the plugin and we need to start looking for things that might make Mach hiccup. 

What versions of Mach are you guys running?

1340
Mesa / Re: Want to try Mesa Elec
« on: January 13, 2011, 12:48:29 PM »
Racear.

The plugin is still in development.  You can test it out if you like, but I would not consider using it for a production machine at this point.  PM me with your email address if you want to try it out.  But there are no guarantees that it will work.  You will have to be pretty knowledgeable about Mach, your servo drives, and your PID tuning to solve your own problems, as I will not be able to give you that level of support. 

Steve