Fanuc 0i-TB Mate - how to verify limit and home switches?
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  1. #1
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    Default Fanuc 0i-TB Mate - how to verify limit and home switches?

    I just acquired a CNC toolroom lathe project with a Fanuc 0i-TB Mate control. The machine did not see much love or maintenance and I'm trying to get it back into commission.

    Anyway, the machine alarms out when homing. After a little investigation, it looks like someone removed the actuator "shoe" for the X axis home switch. I also found the X & Z axis limit / home switches were all gunked-up and had sticky plungers. It think I've got the sticky plungers fixed but I would like to verify the switches are working properly.

    I'm not familiar with the Fanuc control, is there a diagnostic page that shows the status of the limit / home switches?

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    Your best friends in a "project" like this are going to come in the way of books. Download any Fanuc manual you can find on the www. that has Oi-TB in the title to start. Getting electrical, parts, operations and programming manuals from the manufacturer will be your ultimate BFF's. You might have to pay for those friendships but it will be money well spent. It's really too bad if they didn't come with the machine to begin with.

    I know a number of ways to check this switch but out of safety concerns for you I'll leave those ideas to others. My ways may be workable ways but may not be the best, fastest or safest ways. About the only thing I'll offer is you're looking for 0-1 or 1-0 bit changes on an X address in the Diagnostic section of the control. Found either through the "System" or "Offset" then Diag" keys. Might also have to be in MDI. Sorry I can never remember this stuff unless I'm standing at the control. You could use an ohm or DC volt meter, but if you have those skills you've likely already used them.

    Mostly I'm here for the books! They will simplify your repair time and life immensely. Especially the ones from the manufacturer.

    Dave

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    Hit the "system" button, "PMC" button and you should see PMCLAD, PMCDGN, and PMCPRMT, or similar lower left soft keys, can't remember the exact verbiage.

    Hit the "PMCDGN" soft key, then "Status" key, the type "X9" then hit the "Search key. X9.0 and X9.1 should be x and z decel switch inputs unless the machine uses an internal I/O. If it is an internal I/O it will be X1009.0 and X1009.1. You should see the bits change from 0 to 1 when you push the switch. Most machines are wired normally closed so when the switch is pushed it should read 0.

    This info is base on Fanuc rules but not every machine tool builder follows this (X9.0 & X9.1). Most do though.

    Daryl

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    Quote Originally Posted by jj80909 View Post
    Anyway, the machine alarms out when homing. After a little investigation, it looks like someone removed the actuator "shoe" for the X axis home switch. I also found the X & Z axis limit / home switches were all gunked-up and had sticky plungers. It think I've got the sticky plungers fixed but I would like to verify the switches are working properly.
    There should be a dog in the middle of the slide about 3 inches long. Without that dog the machine will never home out. That is crazy that someone removed the dog. If you find the dog and replace it you can hit "Cancel" and the letter "P" on power up and the machine will ignore the soft over travel limits until it references.

    What machine is this?

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    Quote Originally Posted by Other Brother View Post
    Hit the "system" button, "PMC" button and you should see PMCLAD, PMCDGN, and PMCPRMT, or similar lower left soft keys, can't remember the exact verbiage.

    Hit the "PMCDGN" soft key, then "Status" key, the type "X9" then hit the "Search key. X9.0 and X9.1 should be x and z decel switch inputs unless the machine uses an internal I/O. If it is an internal I/O it will be X1009.0 and X1009.1. You should see the bits change from 0 to 1 when you push the switch. Most machines are wired normally closed so when the switch is pushed it should read 0.

    This info is base on Fanuc rules but not every machine tool builder follows this (X9.0 & X9.1). Most do though.

    Daryl

    Ha... I knew there was going to be someone showing up here way smarter then me! I can never remember those button pushes until I'm standing there. Sheesh!

    Dave

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    Quote Originally Posted by 13engines View Post
    Ha... I knew there was going to be someone showing up here way smarter then me! I can never remember those button pushes until I'm standing there. Sheesh!

    Dave
    It's not that I am smarter than you, just more lazy, lol. I do a lot of phone support trying to get my customers to diagnose their own problem, so I tell them, "Hit this button, now hit this button, what do you see? Now hit this button, ect...."

    I would rather teach them how to fix their own stuff than drive hours to their shop and hit a reset button.

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    The customers do learn a lot that way too, how to search ladder logic, how to find inputs etc. I have them send a photo of the ladder, then call them and tell them what to do next. Before long they know how to diagnose problems on their equipment and I get to stay out in my own shop. Win, Win, Ha!

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    Quote Originally Posted by Other Brother View Post
    The customers do learn a lot that way too, how to search ladder logic, how to find inputs etc. I have them send a photo of the ladder, then call them and tell them what to do next. Before long they know how to diagnose problems on their equipment and I get to stay out in my own shop. Win, Win, Ha!
    Boy, I wish techs were like that here! Here all they worry about is their $400+ Call out fee and their $160 an hour to push the reset button.

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    I did the "P" + "CAN" reboot and also verified both switches work by manually operating them and watching X9.0 and X9.1.

    I temporarily stole the -X limit dog to use it for the X home. I had to play a little with its position to get the soft-limits to work, but it homes very well now. I found a replacement dog / cam on ebay and as soon as it gets here, I'll install it for -X limit switch.

    Again, thanks for all the help!

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    Quote Originally Posted by jj80909 View Post
    I did the "P" + "CAN" reboot and also verified both switches work by manually operating them and watching X9.0 and X9.1.

    I temporarily stole the -X limit dog to use it for the X home. I had to play a little with its position to get the soft-limits to work, but it homes very well now. I found a replacement dog / cam on ebay and as soon as it gets here, I'll install it for -X limit switch.

    Again, thanks for all the help!
    The reference (home) position is the value of parameter 1240 (1251 inch) and can be fine tuned with parameter 1850 grid shift for x and z axis. When the decel dog comes off of the switch the machine is looking for the next marker pulse on the encoder, plus the value of the grid shift in parameter 1850. Once this happens the machine position becomes the value that is in parameter 1240/1251. PM me if you want help grid shifting the x and z axis. Too much typing to explain, so I will give you my phone number. Daryl
    Last edited by Other Brother; 01-19-2020 at 11:18 PM.


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