G-REX wiring


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    Default G-REX wiring

    I have recently bought a second hand Hercus PC-200 lathe from ebay which requires new controls (the old controls recommended DOS 3.3 and apparently even then it didn't have the processing power to do accel and decel curves)
    I have lurked around here for a while and worked out that i will probably be ok with a Grex running 3 x G320's however what i haven't been able to find is a wiring diagram for the inter-connections, so i have started my own.
    Attached is a draft of my intended wiring, the remaining issues i was wondering about was how are the limit switches supposed to be wired and do i need the opto-isolators between the encoder and G-Rex (as i remember reading somewhere)
    I have an e'stop on the machine that i will also wire in as well as a pendant but they're for later.

    Any comments would be appreciated.

    Thanks.

    Similar Threads:
    Attached Thumbnails Attached Thumbnails G-REX wiring-gecko-schematics-01-model-1-pdf  
    Last edited by Lost Tourist; 10-15-2007 at 08:40 PM.


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    this is somthing that is needed.
    I was looking for a wile recently
    on mine so far I just have the encoders connected to the drives and all that is connected to the grex from the drives is
    the step and direction wires from each drive to the step and direction axis connections on the G-Rex

    I amjust ready to start motor tuning so
    I cant say that I have a running setup yet
    but I called them and they told me that was all I needed to connect
    that and the 5 volt from the grex to the common
    on the drives to supply the power

    I tried to take a picture of what i have so far but my camera decided to die tonight.

    also they recommended a capacitor digi-key part number P10874-nd connected to the connection 1 and 2 on the drives the (power ground) and the (+ 18 to 80)
    if the wires are over 18 inches long from the power supply
    mine is about 24

    I hope this was some help



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    hey lost tourist, I'm also a long time lurker for the most part and in need of a g-rex g100 wiring diagram. Have you confirmed any part(s) of this diagram?



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    Nothing confirmed yet.



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    just curious but why do you need to parallel up the geck320 encoder wiring with the GREX encoder wiring? wouldn't it be sufficient to only wiring the encoder to the GREX? after all the GREX is relaying the step and direction signals now not the G320.



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    Actually, the G320's won't work without the encoder signals, and the G100 can't do anything with them, as far as I know. Or is the G100 encoder postion available to Mach3 through the plugin?

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Runner4404spd,

    To the best of my lurker knowledge it is a fundamental requirement that the encoders be fed back to the 320's as the GREX only sends a step and direction "request" not "instructions", the GREX says move 2 steps CW and then the 320 has to calculate the control signals to actually move the motor based on feedback to the 320. If the 320 didn't get any feedback it would never know when it had achieved the position as the GREX can't tell it as it only sends requests for movement (in actual fact i think the GREX and 320 talk back on forth but i think the messages are GREX sends new step and direction and the 320 sends back move complete)

    The whole function of the GREX, as i understand things, is that it produces better step and direction signals.

    I think sending the encoders the GREX will tighten up the tolerances as currently errors less the 320's error tolerance won't be noticed as the only error signal the 320's provide is in tolerance/ out tolerance.



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    I noticed that you don't have the +5V "common" on the G320's hooked to anything. Do the drives not need it since it is hooked up via the G100? You wouldn't happen to know why it's there in the first place, would you?

    Also, could you explain the function of the opto-isolators? What would you forsee happening if they were not present?

    Thanks,

    Brian



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    Well spotted Brian,

    Poking around a bit and i think that terminal needs to be hooked to +5V. It's there as part of the step direction circuitry, these signals need to be relative to something so they are relative to the common voltage signal. (they are signalled when lower than +5v)

    I'm not convinced the opto-isolators are "required" however in this thread http://www.cnczone.com/forums/showthread.php?t=35602
    Mariss is stated as saying you should do it (and apparently Mariss is the man when it comes to Geckos) I suspect it is just good practise as using the opto-isolators makes it significantly more unlikely that you will manage to fry your 320 and send your motor power to the computer turning your computer insides to slag. If nothing ever goes wrong you can probably get away without them but what are the odds that's going to keep happening.



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    well, i couldn't wait any longer and decided to start hooking wires up. I'll give you a step by step progress of my day so all may see what doesn't and what will work.

    I started with just 1 driver and followed your (lost tourist's) wiring diagram to a T (minus the opto isolated circuits). The drives just remained in a fault state.

    So i decided to step back and hook up only the encoder to the driver which left only step and dir going from the G-rex to the driver. This did not work either. I then hooked up the +5 common on the driver to the +5V in the power section (under the "USB") on the Grex. This still did not work.

    At this point, i remembered or reread that the ERR/RES on the driver needs to be hooked to the ECN+ on the driver. This ended up working for one drive.

    I then hooked up another driver w/ the same setup, and shared the +5V on the G-rex for both drivers common input. This did not work, both motors would move when jogging only one.

    Finally, i hooked up the +5V (right next to the Step output on the G-rex for each axis, which i think is for the encoder?) to the to the common on the driver. This seemed to work.

    So, as of now, i have the encoders only going to the drivers, and step, dir, and +5V on the G-rex going to the drivers. i have 2 "fully" functional axis now, but don't think this is the way i will leave the setup.

    I hope all that made sense, but i'm in a rush and need to run off.

    Brian



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    Brian,

    I too am thinking about starting to wire things up but i'm a bit behind you as i still need to install the transformer.

    If i understand you correctly your circuit should now look like the attached.

    I assume you are using mach3 with the G100 plugin? If so did you have any trouble mapping the outputs from Mach3 to the G100?

    Attached Thumbnails Attached Thumbnails G-REX wiring-gecko-schematics-02-pdf  


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    Wink

    Hello Lost tourist,

    I`m reading this threat with most aroused curiosity.
    Hope you find an solution. and maybe i can use it

    I have other servo`s then yours, but I have the G320

    Juan



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    Lost Tourist,
    I am using mach 3 and the G100 plug-in. I did not have very much of a problem hooking up the G100. I just followed the directions from mach 3 for the most part. There were some minor issues, but I was able to figure it out and got it all running in a couple of hours.

    Your diagram represents my wiring quite well. A few minor differences: my encoder wires are shielded, and my step/direction wires are not. However, I will buy some shielded wire for these as well, but am not sure whether i should include the +5V line in that cable too. Also, i don't have half of a limit switched wired up to my X-axis

    I didn't pay much attention to your power supply before, but noticed that as of now you only have AC output. You will need to add a rectifier after the transformer to obtain DC output, and then a capacitor after that to minimize ripple voltage. Keep in mind that the capacitor will raise the voltage your voltage by 1.414 times if I remember correctly. So if you have 65V motors, you will need a 46V transformer and consequently, a 65V transformer will output 92V which is more than should be fed to the G320's.

    I spoke to Mariss yesterday as well. In short he said it will not do anything to wire the encoders to the GREX, they only go to the servo drives. (He also then said that stepper systems don't need encoders either which made me want to ask "what the **** are they there for then?", but I didn't). I think that mach 3 can read the encoder inputs however, and this can be usefull down the road, so someday i'd like to wire them to the drive and the G-REX, but this is something to worry about later I suppose. He also said that the step/dir/+5V lines were wired correctly as well. As of now, I am confindent that my wiring (and your diagram above) is right for initial testing. I do want to incorperate an E-stop circuit, limit switches and encoder feedback to mach, so that wiring diagram will change down the road.

    I'm interested in hearing yours and others input on the mach/G-REX/G320 system. I am currently having issues getting my motors to operate at full speed. It's nice to have contact w/ others that are trying to build the same system, and hopefully we can all help each other out in the long run.

    regards,

    Brian



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    Default G-Rex encoder input.

    Brian,

    Think the G-Rex encoder inputs are for use with the unstallable stepper controller Mariss is designing.
    Might also be used to feed a DRO.

    Mark



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    Can anyone confirm that in fact G-Rex encoder inputs are for use with the unstallable stepper controller only?

    I’m seeing the posts talking about closed-loop (or real-time closed loop) and they don't always mention stepper motors, thus confusing everybody.

    Example:

    "Look at the GRex. It is immature at present, but offers a host of advantages. In particular, it runs the nasty timing loop portion that we seem to feel is a problem for Windows on an embedded microprocessor. The performance being seen with it is apparently astounding. It comes with encoder inputs for all axes. Slightly longer term Mach will be enabled to work full closed loop with it."



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    Thanks for the comments everyone.

    Yeah, I also noticed that I hadn't paid attention to the transformer when I drew it and have now added the bridge rectifier and capacitor, though I’m not sure of your maths Brian, I don't see how a capacitor could increase my voltage by 1.414 as it is only a smoothing capacitor and should raise my "average rectified voltage" As I’m using 65V motors I need to rectify a 2x65V sine wave which will give me 65V peaks when rectified, the capacitor is there just to keep near the peaks longer. Since I’m doing a retro fit I already have a 115V transformer output so I’ll probably use that (unless someone can confirm your maths) and rectify to around 57.5V

    The problem I’m currently trying to understand is the spindle motor is 180V 2.5A. Looking at the circuitry I took off I can't see anywhere they supplied that so I’m not sure whether I will try running it at the 57.5V or go for something like a servo amplifier (which I also can't find in the old circuitry).

    As for shielding, again since I’m only retrofitting I leave the encoder cables un shielded as they are unless i start encountering problems.

    And because it'll probably pay off one day I will still wire the encoders to the G100 as well.

    And yes I realise that the input switch is not wired correctly as I’m not sure which why to guess with that, whether it requires pull up resistor or not etc.

    Attached Thumbnails Attached Thumbnails G-REX wiring-gecko-schematics-03-pdf  


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    Lost Tourist,

    Goto the Gecko website and down load the stepper motor basics pdf file.
    Its an 18 page document on stepper motors, However, pages 11-12 cover sizing transformers for power supplies.

    1.414 x AC Voltage (rms) = DC Voltage.

    How are you wiring the encoders to both the G320's and the G-rex? If using the same encoder you'll probably end up with more problems.

    On the 180 supply for the main spindle servo, the power came from the original servo drive.

    Mark



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    Mark,

    So clearly is has been far too long since i have done electronics

    To keep things simple i'll probably just connect the encoders to the G320's

    Now i am stuck with problem of running the spindle drive which is 180V, with a G320 rated to 80V. I have searched around looking for a servo amplifier however all i find is more servo controllers. I'm guessing the solution is more custom circuitry rather than off the shelf stuff.

    Lost Tourist



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    Lost,

    Sorry, to be late getting back with you. Fighting with broken machine at work.

    Think an off the shelf solution is available. First, do you really need the speed that 180 supply? Think that servo motor speed is directly proportional to its voltage. What was the original top speed of the lathe?

    The Gecko 320 should give 44% of that at 80 volts. Since you already have the 320 might as well try it out.

    Another couple of options that use Step & Direction signals.
    Rutex drives (the 2020) is spec’d at 200volt. Down side of Rutex being service and support problems. Upside is they are made in Australia.

    Also have a look at Pico-Systems servo gear. Down side is you’d need a PWM controller, power supply and a servo controller card $375 USD, servo max voltage is 160v (89% of top speed) and Jon is a small business. Up side Jon really knows cnc, has EMC worked out for his system and is very knowledgeable on servo designs. Might be worth emailing him for an opinion.

    What control software do you plan to run the machine?

    If you were in Perth I'd liked to see the machine.

    Mark



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    Mark,

    Late getting back to me? I thank you for getting back to me at all.

    The top spindle speed as spec'd on their website is 4,500rpm unfortunately not having paid attention to what actual rpm i've used before i can't tell whether this is particularly high or not.

    I will probably try the G320 as you suggest simply because i already have it and see what it runs like. If it proves to be a problem i will investigate the other drives.

    As for software i am intending on running it with Mach3 as this seems to be the preferred software around here.

    Unfortunately Sydney is a long way from Perth so you'll have to be content with some pictures when i am underway.

    Lost Tourist



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