Best Practices for EOAT

    I've worked on a handful of cells in the past, but I'm designing a new one now and I want to address the problems we've had on the other implementations:


    Our first problem was that routing I/O through the arm / dresspak is a pain. We addressed this by running only three lines to the tool: Air, Ethernet, and Power. Then add Ethernet-based IO blocks and valves locally to the tools. We also abstract all the IO. The PLC communicates directly with the EOAT's I/O, and passes it to the robot.


    But now the issue is when do I cut the air and power to the valve bank?


    Part of me want to dump air anytime the fence is opened. The other part of me knows that this means maintenance tasks cannot occur. So, I have to leave power and air on the tool, even when the fence is opened.


    This unfortunately means that there is a possibility (through poor coding or device failure) that the EOAT can move while a person is within the fence (unless I equip the EOAT with CIP-safety modules, which I would like to avoid).


    How does everyone else handle this?


    At the moment, I'm looking at using an IO-Link Master on the tooling. There will be a lockout point that cuts the actuator power to that module (Mini 7/8" port, pin 1), which will disable all the motion.


    I'd leave that actuator power on at all times, unless a lockout is applied at the main panel.


    The other option I'm considering is to have air/power on if either the fence is closed/locked OR the teach pendant is enabled.


    Thoughts?

    Edited once, last by schnautz: Correction - I learned that the IO-Link sensors can remain on when actuator power is removed. ().

    Really depends on the tool. A risk assessment is needed. Gripper that moves an inch? Sure keep air on. Air actuated water jet cutter? Probably not a good idea to keep air on.


    Typically you dump air on estop, but keep it on for fence open.


    If you want to be extra safe, tie some contacts to the robot's deadman and bring in actuator power only when the deadman is held in the center position.

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    Check out my example Fanuc Ethernet/IP Explicit Messaging program here!

    yes.... must do a risk assessment.


    all aspects must be evaluated. gripper that moves an inch my still crush or even cut off your fingers. you also don't want part handled by robot to become a projectile, in event that gripper cannot hold the part any more. you may also need to be able to operate tool while teaching (pick and drop points for example). so there is no cut and try solution that works all the time and for every job.


    routing ethernet air and power is common. but you may avoid safety outputs at the EOAT by adding extra wire(s) for power and tying those to safety circuit at the controller.

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    It also depends on the type of valve you choose to use. I have been on installations which might kill the power to operate valves, but they have valves with built in manual overrides so that one could "force" things to open/close, as in maintenance or emergency situations.

    I use safety components (CIP safety, Profisafe, etc) controlled by the safety PLC and the enable/disable of power/air follows the robot's teach pendant safety enable when the fence is open. The robot program makes digital requests to the PLC for EOAT motion. Eventually, the issue comes down to pneumatic valves and rodlocks aren't safety devices. so you try to minimize the impact so its rarely if ever perfect. It can be scary with a 300lb diesel head or 500lb block being swung around.

    I've used a Mobile View HMI to control the EOAT separately from the robot. It's just like a teach pendant with a deadman switch, E-stop, reset, and programmable F keys. Then you can map the safeties from the mobile view to the EOAT to protect any unwanted motion like a robot.

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