Machsupport Forum
Mach Discussion => Mach4 General Discussion => Topic started by: crchisholm on February 04, 2017, 08:27:48 AM
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I ordered and recieved my g540 motion controller and was ready to purchase a mach4 hobby and legacy port plug-in when I stumbled across the following blurb....
"We do not recommend using the parallel port with Mach4 as performance is reduced by both this data connection and the processing and memory power of older computers."
The machine I would use would be either a win xp or win 7 refurbished with 4gb of memory and integrated video. Is this even going to work in light of the statement above???
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I have both the parallel port plugin and an ESS motion controller working with WinXP & Mach4. Overall, the performance is a lot better when using the ESS.
My recommendation - go for a motion controller.
Mach4 is quite heavy on graphics so try your integrated video but be prepared to add a graphics card if necessary.
Tweakie.
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Well, I am now on the gecko g540 path after buying it. I had looked at the ESS, but the coin was tossed and I ended up going form g540 instead. You say you have pp and ess, but I thought the ess didn't need the pp plug in. What am I missing?
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You still need a motion controller (or the PP plugin) to operate your G540. ;)
Perhaps I didn't explain it correctly - I have both the PP plugin and the ESS and comparatively the ESS is better.
Tweakie.
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So, you have Mach4 on the computer (os??). A parallel cable that connects the computer to the ESS. You don't use the Ethernet cable from the computer to the ESS?
Not really trying to pepper you with questions, but I have found it difficult to get my head wrapped around this. I have been using chilipepr and tinyg and am not entirely happy with that arrangement, thus the purchase of the g540.
Have you used the gecko g540 to give you a point of comparison between the ESS and the g540? (obviously, now that I have plunked down the money for the g540, I wan't to find a very good reason not to use it if I don't)
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You still need a motion controller (or the PP plugin) to operate your G540. ;)
The g540 IS the motion controller, right? I was thinking I just need to connect the g540 to the computer running Mach4 and the legacy parrellel port plug in via a pp cable. Is that a correct plan or am I still not getting it? Is there a disadvantage doing it that way?
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Hi crchisholm,
you are correct, a Mach4 licence and a Darwin Parallel Port licence and you are ready to go.
The pulse streams required to activate your stepper drivers (in the 540) are generated by your PC when using a parallel
port. The computer does this by running a timer where it resets a counter and when it counts up to a certain number it generates
an interrupt and the program resets the counter and starts again and also issues a pulse to the parallel port. The timers available
in a PC CPU chip are pretty limited by comparison to microcontrollers suitable for controlling machinery. Microcontrollers have hardware
timers that count up, reset and issue a pulse without CPU intervention. A PC timer requires considerable CPU processing to issue a
pulse stream and are generally called 'interrupt driven' timers.
The downside is that PC CPUs use interrupts for lots of different purposes, a simple one is the realtime clock, it generates an interrupt every
100ms or so just so it can keep the clock on your screen updated. It also uses them to switch between different software threads which we expect
to run at the same time. If two or more interrupts happen at once one will have to be delayed while the other one is processed. As far as our
pulse stream goes it means one pulse is 'late'. This variance in pulse timing is a fact of life with a parallel port and is called 'timing jitter'. There
is a test program which tries to measure jitter and therefore establish if or how well a parallel port will operate.
Some PCs do a good job of running a parallel port with low jitter and some do not. Very powerful and capable PCs are not necessarily any better
than an old XP clunker. Laptops generally do a poor job. Some PCs can be improved by turning certain things off and disabling certain automatic
features. In most cases you cant have different programs running with Mach as one program will interfere with Mach and the regular pulse stream
is broken. The good news is that many PCs do work OK and tens of thousands of CNCers around the world still use the parallel port.
For PCs that wont run a parallel port or if you require very stable pulse streams thats where external motion controllers come into play. They have onboard
either or both an FGPA and a microcontroller which generate very high quality pulse streams and very very much faster pulse streams than can be generated
by a PC alone. The result is smoother motion and also means that the pulse stream can 'keep up' with highly precise servo encoders for which a PC cant.
I suggest you use a parallel port, its a good fit with your existing machine and at a later date add an external controller if you think it desirable.
Craig
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The g540 IS the motion controller, right? I was thinking I just need to connect the g540 to the computer running Mach4 and the legacy parrellel port plug in via a pp cable.
No, the G540 is a stepper drive.
In your case, the parallel port is the motion controller. But what Tweakie is saying, is that an external motion controller is highly recommended. The ESS is an Ethernet Smooth Stepper.
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yeah, the terms are what get me in trouble. I will probably end up getting the ESS, but I want to buy it when I have a particular problem to solve (fortunately, I am not doing this for a living). I have a long history of jumping the gun because I just knew I had to have this thing that is now sitting amoung a lot of other things in my think closet.
So in that case I would be connecting the computer to the ESS via a cat5 cable and then the Ess would use a a pp cable to go to the g540, right?
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Thank you joeaverage. That was a very useful explanation of the process (and also a good illistration of why I will probably end up getting the ESS.
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Hi crchisholm,
I have been reading the thread you started and thought I may be able to pass on at a layman level, some of what I have learned. I too am a confused beginner at this CNC stuff, but have slowly gathered enough information to probably be somewhat dangerous.
I have servo motors on my CNC, so am using the Gecko 320X, but I am using the ESS, so I may be able to let you know about what I have found out.
One potential issue with using parallel port connection is the limited amount of i/o (in and out) available. If you intend on using your mouse and PC monitor to control the machine, then perhaps you will only need inputs for things like E-STOP and Limit Switches.
If you would like to control the machine via external buttons for things like Cycle Start, Feed Hold, Jogging, MPG etc., then it is likely unless you implement more parallel ports, that you will quickly run out of inputs and perhaps outputs.
If you go for the ESS, then it can be advantageous to use a good BOB (Breakout Board). There are several good ones on the market for the ESS, personally I have the MB2 from CNCRoom in Thailand.
It is a very good board and if you buy the ESS from him as well, it comes installed onto the MB2 and utilises all three ports on the ESS. The MB2 has quite a lot of I/O, as well as some other nice features, like industry standard 24V inputs and outputs. There is also an on-board Analog speed control, which can be used to control the speed of you Spindle via a VFD (Variable Frequency Drive) or a drive that uses +/-10V.
This is the link.
http://www.cncroom.com/interface-board-mach3-mach4/smooth-stepper-ess-mb2-bob
You asked if the ESS would connect to the g540 via a parallel port cable. That is correct, although if you use a break out board with the ESS, then you would connect each wire at the ESS end of the PP cable into its respective input or output on the Break-Out Board.
There are other really good CNC motion controllers on the market. The ESS is a very good board, and has the big advantage of many users around the world, which helps for support. Another very good board for the price is the PoKeys57CNC. A lot of well thought out features for a great price. And from experience, very timely and helpful support. I own the PoKeys 57E, which I am using to increase the amount of inputs on my front panel.
Hope there is something in there that you may find interesting. And I hope you find it all as stimulating as I have.
Craig
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So, I have the g540 and probobly need bite the bullet (or drink the koolaid) and get the ESS, but I can not quit figure out how the two devices connect to each other. The g540 only has only a parrellel port and the ESS does not. Are there some example diagrams out there somewhere that show the physical connections between the power supply, ESS, and g540.
A couple good diagrams might slow the steady flow of questions coming from me as well.
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IIRC you use a 26 pin header to db25 ribbon cable and then connect a a DB25 to DB25 (parallel port cable) in between.
This link should have everthing you need.
http://warp9td.com/index.php/documentation/doc-ess#Schematics (http://warp9td.com/index.php/documentation/doc-ess#Schematics)
Mikie
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So, I have the g540 and probobly need bite the bullet (or drink the koolaid) and get the ESS, but I can not quit figure out how the two devices connect to each other.
One each of these:
http://www.ebay.com/itm/11-4-Long-DB25-to-IDC-26-Pin-F-F-Printer-Port-Ribbon-Cable-Connector-Adapter-/401144802953?hash=item5d6617ee89:g:iy0AAOSwo4pYb6Ct
http://www.ebay.com/itm/25-Pin-DB25-Male-to-Male-M-M-Gender-Changer-Adapter-SGC-25MM-/221273598387?hash=item3384ef29b3:g:KlgAAOxym2BSGvbc
The ESS needs it's own 5V power supply, and the stepper motor power supply connects to the G540.
The only wiring to the ESS is the 5V power supply, ethernet cable, and ribbon cable to the G540.
The G541 manual should cover all other wiring..
Also, the ESS is overkill if your only using a G540, as the ESS has 3 ports, and you'll only be using 1.
A UC100 is quite a bit cheaper, ad will do the same thing.
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As Gerry noted the G540 does not need all the capabilities of an ESS SmoothStepper
and can work with the UC100.
You can also use similar devices from others such as the PoKeys57CNCd25 or the
PMDX-411.
http://www.pmdx.com/PMDX-411
All of these devices are USB and do not need an external power source.
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I was thinking that this was a Mach3 thread.
There is not currently a Mach4 plugin for the UC100, although I believe that they are working on it.
So the PMDX-411 would be a better choice for Mach4 imo.
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So the PMDX-411 would plug into a usb on the xp machine running mach4 and the pp of the g540. I wouldn't need the legacy pp plug in and I would not give up any functionality that might be useful to a hobbiest like myself on the ESS?
That sounds pretty good.
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The PMDX-411 will plug into the G540 directly without adapters or cables. The USB
cable of the PMDX-411 is fairly short (18") so you may want an extension for that.
You do not need the Legacy PP plugin for this configuration. The PMDX-411 is
supplied with its own plugin.
The PMDX-411 provides only the I/O equivalent to one parallel port, whereas the
SmoothStepper would provide two additional parallel ports worth of I/O that could
be used with other boards along with the G540 if you wanted to do something like
build your own console with buttons and lights.
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Hi crchisholm,
if you are going to lay out some bucks for an external motion controller then you should consider whether it will do
all that you require both now and some way into the future.
The PMDX-411 is a great device but it has a limited number of inputs and outputs, one 'ports' worth. The PoKeys 57CNCd25 is
another great device but also limited to one 'ports' worth of IO. Both devices are well priced and a perfect fit for your 540.
They will offer somewhat more IO than your used to with GBRL.
For an extra $60 you can get an ESS which has three 'ports worth' or for similar money the PoKeys 57ECNC which has even more.
It occurs to me that if you are going to buy an external controller it makes sense to get one that has some extra capability that you
may well use in the years to come.
There are of course even more expensive alternatives as well, there always is!
Craig
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joeaverage: those are very good points, but I need to view them in the context of my reality. I am 70 with limited income, not in great health, and find in increasingly more difficult to wrap this old brain around new complexity. I need to think about what you've said, but to be brutally honest with myself, I don't see this going to much further than I am going now. This is s small open source OX CNC, and I don't have the space or plans to go much more elaborate. Most of my projects are aimed at photography (multi exposure macro compression) and some simple robotic applications, none of which are of any real interest to anyone but myself, so it's not an entrepreneurial exercise.
Thank you for your insight, though. I do need to think about that. It would be helpful if I could figure out what sort of things I might want to do in the future that might use more ports. At present, I am drawing a blank. You're right that $60 is not a large sum of money, but obviously, it occupies a certain percentage of a pretty small monthly income, so I have to be smarter about what I do than I did when I was making the "big bucks" ;) .
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Hi crchisholm,
the simple expedient then is don't bother with an external controller at all. I used a parallel port for several years with Mach3 and had
a great time! Mach4 and ESS add scope but there is little or nothing that I couldn't achieve with a parallel port and some imagination.
Craig