How to program open & close of grippers using digital/tool output


I have Robotiq 2 fingers gripper and vacuum gripper installed on UR5e cobots. I could program them using URcap in Polyscope properly. My question is, is it possible to use ‘Set’ function to program the open & close of the grippers? I tried to ‘Set’ either DO or Tool output but it did not work.

I programed like this:
SET TO[0] = on or off

I could program in such a way successfully for other end effectors wired to DO in the UR control box. So I am wondering if you may advise if (and how) it is possible to program like this for Robotiq grippers?

Thank you very much!

You can change what controls the Tool IO here. However, I think the robotiq grippers use the RS485 serial connection if I’m not mistaken. Since they use some force compliance and variable close/open distances. Don’t quote me on that though, I’ve always just used their CAP to control them.

Hi Eric,

Thank you very much.

I tried to follow your suggestion, but it has not worked yet. Could you please advise what the program should look like in that case? I suppose that I still need to use SET DO or SET TO but none of them worked after some attempt. I did not think it is relevant to DO as there was nothing wired to DO. But what is the right channel to control the gripper?

Robotiq does indeed use the serial connection to control their grippers through the URCap, so you won’t be able to control the grippers through digital outputs.

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Hi Eric,

Thank you very much for you clarification. My motivation to use digital outputs is to program the grippers in the third party software like RoboDK. I have never been able to physically open & close the robotiq grippers via programming in RoboDK which is supposed to be done by writing a piece of code. But I am not sure if and how the URscript of the gripper open & close can be transferred into python script in RoboDK. I am wondering if you may have any advice?

Haven’t worked with RoboDK myself, though I have heard of it before. If you are able to successfully get that software to see the grippers, I would assume you could just write whatever script the CAP is writing when you use those nodes. I would just go to your real robot, and write a program that just closes the gripper, then opens the gripper. You can then save this program, then insert a Script node and choose “File” and select the .script version of the program you just made. This will give you the exact URScript code the robot is executing to open and close the gripper. If the CAP could be installed into RoboDK correctly, I would assume this code would be able to be simulated as well.

Hi Eric,

Thank you very much for your informative reply. I will try and see if it works.


Sorry I cannot help you for your specific question. I would like to know where did you get the head with both the gripper and the vacuum gripper on it.

Thank you.


I haven’t use it myself with RoboDK, but you can have a look at the following article :

Look pretty straight forward,


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