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  1. #1
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    Fanuc 0M Ladders

    Can anyone please explain some things about Fanuc Ladders...

    Are they what I would normally call Microcode?

    Where are they stored in a 0M controller?

    Can they be seen?

    Can they be called from a macro to do certain small functions like move an axis?

    Can they be saved to a PC like the parameters?

    Is there another way to make a backup copy to prevent a disaster?

    Thanks in advance.

  2. #2
    Community Moderator Al_The_Man's Avatar
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    Depends on the model the early 0 models could not display it, the parameter to turn it on in the later ones is P0060 bit #2 set to 1.
    They are commonly stored in eprom, the ladder is written in a display format based on Boolean logic.
    All the M,S,T codes are decifered in the ladder logic.
    There is a bus called the BMI, Basic Machine Interface which has registers, Gxxxx and Fxxxx, to allow the CNC side to communicate back and forth with the ladder (PMC).
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
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    Thank you Al.

    Any more info on this subject?

  4. #4
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    You can read and write on some PMC variable via a macro but it is limited.
    system variable #1000 to #1015 are used to read some PMC data and system variable #1100 to #1115 are used to write on PMC data but they have to be already linked in the ladder logic.

    #1000 to #1015 are linked to G130.0 to G131.7 in the ladder.
    #1100 to #1115 are linked to F162.0 to F163.7 in the ladder.

    On my machining center, in the ladder logic machine lock button (MLK) wich is G117.1 activate G131.7. So I can read the state of the machine lock button via a macro with the system variable #1015 and use it in conditional sentence like IF[#1015 EQ 1] GOTO 50. But it is the only thing that is linked in the ladder logic so i cannot read or write anything else without altering the ladder.

    All this info is for a 0M-D control. If you can see your ladder, look for G130.0 to G131.7 and F162.0 to F163.7 and you will know wath you are able to do from macro.

  5. #5
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    I am going to correct you, Al. The BMI is not a bus but a simple standard interface using pre-assigned i/o that corresponds to another control, such as FS3, FS6 for those machine toll builders who want to maintain consistent interfaces between the various Fanuc controls. To my knowledge, the BMI was not available on the '0' series.

  6. #6
    Community Moderator Al_The_Man's Avatar
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    In some controls it could conceivably be other than common bus registers, I am going by my Fanuc course notes for the 15 where it was taught that the BMI is a communication bus between CNC and PMC co-processors using G and F registers.
    The 15 Connection manual is also labelled BMI interface and is a list of the pre-assigned registers.
    The important thing is the concept as to my knowledge there is not many commercial CNC's that do not have co-processors for CNC and PMC.
    I realize that before the 0 the CNC communication consisted of pre-assigned inputs/outputs and the MTB was free to use relay logic or any 3rd party PLC to integrate the machine control.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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    Right, so what I understand then is that there are 16 General registers and 16 Floating-point ones?

    Or is it just 16 G-bits and 16 F-bits?

    Are they bi-directional or is it e.g. F in and G out?

    Samu, how do you get from "(MLK) wich is G117.1" to "activate G131.7" pls? Do you have any docs?

  8. #8
    Community Moderator Al_The_Man's Avatar
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    G = PMC > CNC , F = CNC > PMC. 8 bit registers, Not bi-directional.
    It is a long time since I integrated a 0, I have since gone over to Mitsubishi, they use exactly the same concept.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  9. #9
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    Quote Originally Posted by Zoner View Post
    Samu, how do you get from "(MLK) wich is G117.1" to "activate G131.7" pls? Do you have any docs?
    It is in the FANUC 0 series maintenance manual that all the PMC signal are listed. It is FANUC that linked MLK to G117.1 but it is the machine tool builder that wrote the ladder to activate G131.7 by the MLK button.

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    OK, great info, I have a less-dim idea of it now.

    To complete a little more info...

    Can they be backed up to the PC and restored when needed?

    Or is it only by copying the physical EPROM(s) to (an)other EPROM(s) or to a file using an EPROM Programmer?

  11. #11
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    Quote Originally Posted by Zoner View Post
    OK, great info, I have a less-dim idea of it now.

    To complete a little more info...

    Can they be backed up to the PC and restored when needed?

    Or is it only by copying the physical EPROM(s) to (an)other EPROM(s) or to a file using an EPROM Programmer?
    According to Fanuc CNC America, They are not able to download the ladder program from the older machines, (example: 0M controls 1986 but they can copy the Eprom if your willing to send it to Chicago). And Hardinger LLC. UK. If you need the ladder program you have to get in contact with them, it is preparatory information. They will if they can provide the EPROM. for a price. I know because I'm negotiating with for the Eprom for my machine. Due to a E01 error.

  12. #12
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    Re: Fanuc 0M Ladders

    Hello. I got old Fanuc 0M CNC milling machine and need Fanuc Ladder II program but cant find that anywhere. Maybe someone have it and could share? Thanks.

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