Universal Robots Forum

External RTDE connection(onrobot)

hello all,

I am trying to read the robot data using RTDE connection. I have downloaded the rtde-2.3.6 and I am using the build-in example record.py to read the data. In addition to the robot data, I am trying to read the onrobot(sensor and gripper) outputs by the following commands(in the XML files):
output_double_register_ X,X: [24…47]
output_int_register_ X , X: [24…47]

After running the code, The .csv file(which is the record.py output) successfully contains the robot(timestamp, target q…) outputs but the onrobot outputs are all 0.

Thank all :slight_smile:


i think your gripper uses a different interface for communication. You should check your grippers doc first. If you don’t have access to any documentation you can wireshark your ethernet (?) connection to see which ports are used, e.g. 502 for standard modbus communication.

Thanks for the quick answer,

True the onrobot external device uses a different port and different IP. I can connect directly to the external devices using web access for example or by sending tcp/udp packets. I thought the external parts communicate with the robot and RTDE can include this communication somehow. I want to use RTDE to read all the robot and external devices information(if it’s possible) in realtime. Can you use Modbus communication in real-time?

I have ever used port 502 to get robot parameters.
I studied how to access port 502 by reading the link below.


So you are using Modbus to access the robot and external parameters in real-time and then control the robot using RTDE? Is there any other way of using only RTDE?

Just to clarify, both RTDE and Modbus are real-time protocols the only difference is Modbus TCP/ IP vs TCP/ IP?