libfranka: UDP receive: Timeout

[hesic73]

System Details

• OS: Ubuntu 18.04 (RT Kernel)
• Franka Arm System: 4.0.4
• libfranka: 0.9.0

When attempting to run communication_test, I encounter a UDP receive timeout error:

$./examples/communication_test 172.16.0.2
libfranka: UDP receive: Timeout

The Franka arm is reachable via a ping test. However, the issue may be related to our network controller hardware.

Suspected Cause

This may be related to https://github.com/frankaemika/libfranka/issues/46.

Our workstation uses an onboard RTL8111/8168/8411 network controller, while the minimum system requirements specify a network card supporting 100BASE-TX. Additionally:

• The MTU is set to 1500 on our workstation.
• A tcpdump capture shows UDP: Bad length 2371 > 1472, indicating that packet sizes may be exceeding the network controller’s supported limits. Could this be the source of the timeout issue? Any insights or recommended adjustments would be appreciated.

[sgabl]

Hi @hesic73, thanks for providing the details. Your robot is on the quite old FER SW version 4.0.4 - 2020-10-05 compared to the 'recent' 4.2.2 - 2022-08-11. By any chance, can you perform an upgrade?

This error occurs if the connection to the FCI (via TCP) is OK, but the robot state for running the control loop can not be received by libfranka. Please check that your workstation’s firewall does not block incoming UDP packets (see sudo iptables -L).

If that does not help, please use wireshark or tcpdump to record a short pcap file and send it together with the logs of the robot to support@franka.de.

[hesic73]

Hello, I've identified the issue—it was due to the firewall blocking UDP on that port. Thank you for your assistance!