Fanuc reading a PMC input
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  1. #1
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    Question Fanuc reading a PMC input

    How we can reading an input (PMC) in CNC program?
    to use an input for a condition in CNC program. I want to insert a condition in my program if an input for example X0.1 is on the program call a subprogram otherwise continue the lines.
    thanks

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    Since you used "PMC", I assume you are asking in regards to Fanuc controls....

    Can only be done if the ladder program transfers the input signal to a user macro input bit.

    Few machine builders include this in their ladder program. Depending on control model and configuration a user may be able to modify the ladder to do this. Unless you are experienced in ladder logic, this would be a job best left to an experienced tech. Incorrect modifications to the ladder could leave the machine inoperable or dangerous to operate.

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    I totally agree with Vancbiker.

    Wrong move and you can mess up a lot of things.

    talk to your machine supplier.

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    Instead of messing with ladder, use SKIP input to connect your signal, and G31 move to examine if it is either "1" or "0". I've done it in many cases, simple and does the job.

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    Thanks a lot
    Is it possible send me an example?
    best regards

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    Quote Originally Posted by m_ghaff2000 View Post
    Thanks a lot
    Is it possible send me an example?
    best regards
    If some other instrument is connected to the SKIP input, you will have to use CHANGE OVER contact of M-function operated relay in order to control what is connected.
    Assuming that your device is connected to the SKIP input, you will have to use following macro routine:

    YOUR PROGRAM
    .
    .
    .
    (CHECK STATUS OF YOUR DEVICE)
    G91
    #100=#5023
    G31Z-0.01 F60
    G53
    #101=#5023
    G0 Z[#100-#5023]
    G90
    IF[ABS[#100-#101]GT0.005]GOTO1000 (INPUT STATUS "0")
    M98P**** (INPUT STATUS 1, CALL SUBROUTINE)
    N1000
    .
    .
    .
    M30

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    Quote Originally Posted by PROBE View Post
    Instead of messing with ladder, use SKIP input to connect your signal, and G31 move to examine if it is either "1" or "0". I've done it in many cases, simple and does the job.
    Could be a problem if the OP's machine has a spindle probe or tool setter already using SKIP. One can have multiple devices inputting to SKIP, but that is best done by incorporating an M code to select devices. Of course then ones machine would have to have additional M codes provided by the machine builder ladder program.

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    Quote Originally Posted by Vancbiker View Post
    Could be a problem if the OP's machine has a spindle probe or tool setter already using SKIP. One can have multiple devices inputting to SKIP, but that is best done by incorporating an M code to select devices. Of course then ones machine would have to have additional M codes provided by the machine builder ladder program.
    This is quite easy. I would use the COOLANT ON signal. Whenever coolant is ON, the signal in subject is connected to SKIP, and it can be examined as explained. Whenever it is OFF, other device (probe) is connected. Probing is never executed with coolant ON.

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    Quote Originally Posted by PROBE View Post
    This is quite easy. I would use the COOLANT ON signal. .....
    IMHO, a pretty poor hack. As a last resort, OK. I'd exhaust all other options first.

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    You didn't mention your control model, but I think Fanuc has kept everything the same since forever. The logic you need is dead simple:

    |------| |----------------( )---|
    X0.1 G0054.0

    Macro variable #1000 will be 0 or 1 depending on input X0.1. I would much rather add one run to the ladder than try to shoehorn the functionality into the skip signal. Doing that would work, but I prefer not to make 3 right turns when I want to go left.

    The manual you want is B-64483EN-1/03.

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    Yes, way better than jury rigging the skip signal. If the OP has edit capability of the ladder the basic rung as shown might just be all he needs.

    Never got a description of what the proposed use is. The logic would get more complex if he needs to latch the state of the input, filter contact bounce, have some time delay, memorize the input state in case of power failure and so on.

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    "I would much rather add one run to the ladder than try to shoehorn the functionality into the skip signal. Doing that would work, but I prefer not to make 3 right turns when I want to go left."

    Yes, it would be much nicer if left turn would be available. But it is not. Under these circumstances making 3 right turns is much easier then reconstructing the road crossing structure, especially not being sure that one has skills and tools to do it.

    We are living in the real world and have to give real, simple and straight forward solution to problems. There is not enough time in the field to deal with all "ifs" (if the ladder is editable, if there is free input on interface terminal etc...) The solution I gave, maybe in someone's opinion not very elegant, is simple to apply, is working and does not harm other system's functions.


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