Can you help me understand the root cause of the C289 over-current/short circuit error that is being encountered in a short circuit from an IO tool?
The error is leading to damage of the tool attached to the IO and the log file indicates a short circuit event with the message ‘Tool connector short circuit detected on digital output 1 low side’. I am seeking insights on what could be the possible reasons for this issue.
Could be a bad force torque sensor, or a screw came loose in wrist 3 and is shorting stuff out. You can take it apart, or just contact your distributor/UR for service
If you take out the tool and the error keeps happening, it could be the force sensor or a screw as shown in the previous comment. If the error happens while only the tool is connected, review the installation settings for the IO (PNP, NPN or Pull), and the connector on the tool side.
We could do with a bit more information such as robot type, has it worked before etc. 
To me it sounds like you are connecting your tool as PNP (outputting high), where the tool I/O is NPN (outputting low). This results in your tool getting 24V on its 0V input and 0V on its 24V input.
If you are using a CB robot, the outputs are always NPN, and you must connect your tool’s 0V to the tool digital output (TO0 or TO1) and 24V to the tool’s 24V output.
If you are using an e-series robot, such as described by cgs, you can change the output in the installation settings to work as PNP (it should default to this, though, afaik).
@efn @cgs @eric.feldmann Thanks for the insight , I have another question , I am using e -series robot and I suppose it works in PNP configuration. Still Its having short circuit that I mentioned above while I connect the tool. So How do I verify that the tool is configured for NPN or PNP ? and also what if I choose dual pin power ?
You’ll have to take it apart to check the wiring or read the documentation, if such exists…
Or put the tool output to NPN and see if it works. E-series has the option to output either PNP or NPN, if you go to Tool I/O in the Installation.
To verify the tool IO configuration, you have to check it on installation tab, and then on the left side “Tool IO”.
These settings are the default ones, however, this can be temporarily changed with URScript commands such as ‘set_tool_digital_ouput_mode’ or ‘set_tool_voltage’. From the documentation:
So what I would do is to review the installation tab, and then on the command line (or after transfering all the UR programs to another computer) search for “set_tool_digital_ouput_mode” and “set_tool_voltage” on the .script files to see if any program is using those.
Electronics components can get burnt if you try to use them on the wrong configuration (they require PNP and the installation is NPN, or viceversa), and poor electrical designs lead to those errors too. The best way to handle these is that the electronic design of the tool has diodes and a voltage/current limiter on the input/output and VCC pins. Also adding octocoplers to guarantee a good electrical separation between the UR signals and the ones that the tool processes. That way when the UR settings are wrong, the UR IO signals cannot get through and the tool just won’t start up, so no shortcuts and no safety errors.
@efn @cgs Thanks a lot for your insight, I checked the URCap code and it looks like the URCap is using DUAL_PIN_POWER_MODE, so when I am using dual pin power mode in e series, is it NPN or PNP or it is something else
DUAL_PIN_POWER_MODE according to this and this documentation, it means that two pins turn into an additional power supply for the tool, and that the tool outputs are disabled.
So check your tool manual to see what configuration fits and apply changes in your UR program/installation if required.
If the URcap is using dual pin power, it is made for the e-series. So it’s not a question of NPN or PNP.
Sounds most of all like the tool is defective, I’m afraid. I would contact the manufacturer or supplier for a service check.