J1 axis set to mm not degrees

  • Good morning,

    I came in over shutdown to work on a robot that always jogs at an angle in world. I assumed it was not referenced properly and planned to re-reference it and re write the programs over the next 3 days to be ready for startup. I found today it was referenced properly, but that joint 1 seems to be scaled in MM instead of degrees.

    If I rotate J1 90 degrees the position value reads ~1800. The axis limit for J1 is -4000mm to +4000mm. I have never seen this before and am at a loss as to where to start. The robot has been running production for ~18 months without issue, other than difficulty teaching points. It is an M16iB-20 with a RJ3iB controller.

    Any help would be appreciated,


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  • Update after I spoke with Tech support. The robot is set up as a track robot, not a standard 6 axis with a rotating J1. Any suggestions on how to change it now would be appreciated. Fanuc is working on it as well but they aren't certain how to change it and are on a skeleton crew over the holiday.



  • • To change the position value,move the cursor to the position number and press F5, POSITION. The position screen will be displayed showing the Cartesian coordinates or joint angles of the selected position.
    • To change the format of the position from Cartesian coordinates to joint angles or from joint angles to Cartesian coordinates, press F5, [REPRE]and select the coordinate system. The position is converted automatically.

  • Solution found. Working with Fanuc Tech support they used the wrong core robot in a software upgrade we purchased 18 months ago during installation. The robot core they used is a M16iB/20T. We have a standard M16iB/20. The "T" designates a track mount robot that does not have a swiveling J1 axis. It moves along a track for J1, hence the mm reference instead of degrees for J1 only. I've had no experience with a robot like this so it wasn't even on my mind that this could be the issue. Data sheet for what I'm talking about is below.


    Unfortunately the only fix is to have another software update performed with the correct core robot, and Fanuc does not have the personnel in house this week to do this.

  • My humble opinion is that Fanuc made a mistake so they should see if there is a high level Fanuc integrator that has a qualified tech available if they can't send a Fanuc tech. They should send them the software to load and then reimburse them. They have done this in the past. Fanuc brags about how highly skilled their integration network is, so there shouldn't be an issue. It's worth bringing up to get your cell running ASAP.

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