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IndustryArena Forum > MetalWorking Machines > Uncategorised MetalWorking Machines > Interactions between “PROG RUN” and “MDI” modes
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  1. #1
    Join Date
    Feb 2009
    Posts
    3

    Interactions between “PROG RUN” and “MDI” modes

    Hello there, I am new to CNC programing and am facing a challenging task. Hope you can contribute/help.

    My query is about interactions between “PROG RUN” and “MDI” modes.

    Basically, I have written of sub-routine with lab-view for visiting points on a surface. The sub-routine enables to bring my tool holder (equipped with a camera) close to points of interest. In practice, this is done through a txt file that the CNC reads and executes in PROG RUN mode. As there is four points the CNC does it through four sequences. At the end of each sequence, the operator must handwheel the camera for fine adjusting the position. Then he captures the set of coordinates. Practically, the acquisition of coordinates is carried out by a four step explained hereafter. First there is a M0 in my sub-routine, operator select the handwheel mode, using electronic handwheel he fine tunes the position, he selects the MDI mode, he records the coordinates in the MDI mode, and he selects PROG RUN mode for executing the rest of the program. Indeed, he stores XYZ coordinates in MDI through the hard key “capture actual position”. This works fine till he goes back to PROG RUN mode. The reason is that the CNC needs that he pushes the “REST POS AT” soft key, push “RUN” button, push “RESTORE POSITION” soft key, push “RUN” button, push “RUN” button n times according to number of axes used for fine tuning. In other words, it is a quite demanding procedure for operators.

    Any suggestions will help ?

    Additional information:
    Brand: Heidenhain
    Model: TNC430
    NC: Software number 280472 13
    PLC: software number BASIC—31
    SETUP: 280641 13
    Renaud Jourdain PhD
    Cranfield University / Precision Engineering Institute

  2. #2
    Join Date
    Jun 2015
    Posts
    4131

    Re: Interactions between “PROG RUN” and “MDI” modes

    hello

    At the end of each sequence, the operator must handwheel the camera for fine adjusting the position
    is the camera ( rigid ) inside a toolholder ? tool change sequence precision isn't enough, so you still need to fine tune ? how much do you fine tune ?

    can you share a list of Z coordinates for each run, like for an entire day, or 50 cycles ?

    about less keystrokes, i can't help, because i don't have experience with heidenhain; i can do it on okuma ; kindly

    ps : why are you using the camera ?
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  3. #3
    Join Date
    Feb 2009
    Posts
    3

    Re: Interactions between “PROG RUN” and “MDI” modes

    Hello,

    Camera is mounted solid into the toolholder. However at the end of this process I take camera out manually. Unfortunately, I cannot share Z coordinates because each mirror is unique. The reason why I want to implement this routine is for safety. Indeed, prior to be ready for my machine mirrors goes through grinding, robot polishing (for months). Once mounted in my machine if operator comes to touch mirror with camera or the distance between ion beam source and mirror’s surface is not correct is money through the door.

    For your information, instead of regular milling tool I use an ion gun in vacuum. It is a big pressure vessel with a motion system embedded. The machine is built for corrections of surfaces at atomic level (astronomy and space applications). The machine has five axes and algorithm is based on dwell time.

    Best,
    Renaud
    Renaud Jourdain PhD
    Cranfield University / Precision Engineering Institute

  4. #4
    Join Date
    Jun 2015
    Posts
    4131

    Re: Interactions between “PROG RUN” and “MDI” modes

    hello renaud, i was going to tell you to try the Heidenhain forum, but i saw that there is no such thing arround here ...

    such things are " high - specifics ", not because they are complex, but simply because there are rare requests for such behaviours

    far as i understand, after you record the current-position in MDI, you lose time by going to automatic mode, running the program + restoring the position previously recorded in MDI; it seems simple, but repeating for many times, will kill you also i believe that you wish to reduce the operator
    intervention time, so to avoid the " human error ", especially because of those fancy mirrors

    if i get it right ( i hope ), you need to run the program directly from the current possition, without loosing coordinates, etc ...

    i recently implemented such a thing on an okuma cnc arround here : is simple, few system variables, and i'm done

    maybe there are some system variables that will deliver what you need : system variables for current possition ( on okuma you may read ball screw position, encoder origin, tool offset, tool wear, program zero, axis travel, zero shifts, etc )

    try a near-by
    Heidenhain tech center ? search for a skilled heindenhain person in near-by shops ? go on a technical holiday tour

    what you wish to do is a very good idea / kindly



    ps : i just had an idea : after you put the camera in desired position, reset the machine, then go to work-coordinates-page, and record the current position as a new zero; from the program, run that new-zero ... is not what you wish for ( or at least is not as fast as another method that an okuma cnc can deliver ), but i guess it should be possible : talk about this with your operator; it may be faster, maybe there are less kestrokes; even if the number of keystrokes is the same, this approach eliminates the need for the operator to restore the position for each axis, because the program will restore all of them, at once

    on okuma it would be like this : adjust camera position + reset the cnc + run the program / 2nd kindly

    ps2 : depending on desired positiong tolerance, maybe you should use :
    ... uni-directional positioning ( so to manage backlash )
    ... exact stop function ( so to increase positioning accuracy )
    ... small droops / ipw
    * those are not a must; cnc normal behaviour may be enough for what you need / 3rd kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  5. #5
    Join Date
    Feb 2009
    Posts
    3

    Re: Interactions between “PROG RUN” and “MDI” modes

    Hello ,

    Thank you for your replies.All your comments and suggestions are really appreciated.

    Fingers crossed I will be able to find a solution. As you know there are all sort of system variables that I have not explored yet. As you wrote, the issue in this very process specific process is that operator is requirred to do two things. Adjust the position (XY plan) of the camera by typically making sure that the edge of the miror is in the centre of the screen. Second, move the camera along Z to be in focus. Then he has to reach the second point of interest. Then he has to reach third point. Finally, he has to reach fourth point of interest. The restore position may be a system variable. Personally, I do understand the reason why it does restore position only for safety aspect. Whatever, I will be happy if it powers up all five axes and goes for reaching the following position through one set of instruction at the time.

    Thanks again,
    Renaud
    Renaud Jourdain PhD
    Cranfield University / Precision Engineering Institute

  6. #6
    Join Date
    Jun 2018
    Posts
    362

    Re: Interactions between “PROG RUN” and “MDI” modes

    I probably don't understand your machinery or requirements properly but you say two issue are to prevent the camera from touching the mirror and the ensure the distance between ion beam and mirror is correct. The "points of interest" are within a TXT file but what defines "points of interest" to generate the text file?

    Not being familiar with the CNC controls you have but do they allow you to set a safe (limit) point (maybe in new co-ordinate system G54-G59) on a given axis (Z in this case) such that the camera (on Z) cannot get close enough to ruin the job? I'd imagine the mirror is concave so the Z depth would be a function of the X and Y coordinate to calculate a safe depth?

    Perhaps you could use the g54-g59 series to set new work coordinates for camera operations and then return to the original (G53/54) tool path? As mentioned, you might be able to call the interruped co-ordinates with a macro and a few variables to help with new/old coordinates?

    Cheers,

  7. #7
    Join Date
    Jun 2015
    Posts
    4131

    Re: Interactions between “PROG RUN” and “MDI” modes

    hello again renaud

    As you know there are all sort of system variables that I have not explored yet
    actually i don't know if there are system variables on your cnc

    The restore position may be a system variable
    i don't know; on okuma cnc is a sum of some system variables; 2 or more

    I will be happy if it powers up all the axes and goes for reaching the following position through one instruction at the time
    try this sequence on your cnc ( it does not require system variables ) :
    ... adjust camera + reset cnc
    ... in work-coordinate-system (wcs) table ( program zero ), declare 0 at position 2 ( considering that main program works in 1 )
    ... in automatic mode, select a 2nd program, that uses "wcs number 2" : it should send your camera in the previous adjusted position

    kindly

    ps : using system variables, to achieve what you want, is not a must : thus there may be several solutions, but not all of them will require system variables
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

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