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Network communication

Real-time motion commands and status are sent over UDP unicast. On first setup, typical issues are wrong local IP, firewall blocking, packet loss, and NIC compatibility.

UDP socket open failure​

Messages like “invalid parameter” or “invalid address” usually mean the local (host) IP is missing or wrong.

Finding the local IP​

  • Ubuntu: ifconfig
  • Windows: Settings → Network & Internet
  • Windows CLI: ipconfig

Example: filling in the local IP​

int main() {
    // Robot 10.0.2.160, SDK on Windows PC, local IP 10.0.2.121
    rokae::xMateRobot robot("10.0.2.160", "10.0.2.121");

    // Or when connecting:
    rokae::xMateRobot robot2;
    robot2.connectToRobot("10.0.2.160", "10.0.2.121");
}

No robot status before timeout​

If the IP is correct but you still see no robot status before timeout, UDP is likely blocked.

Windows​

  • Check firewall inbound rules for the app / ports. Windows inbound rules
  • Allow the firewall prompt on first run. Firewall prompt

Linux​

Verify data reception:

nc -vul -p 1337

Run any real-time example and check for traffic from the robot. If 1337 / 1338 never receive data, inspect firewalls by type.

UFW​

sudo ufw status
sudo ufw allow 1337/udp
sudo ufw allow 1338/udp
sudo ufw status

If needed, disable:

sudo ufw disable

firewalld​

sudo firewall-cmd --state
sudo firewall-cmd --list-ports
sudo firewall-cmd --add-port=1337/udp
sudo firewall-cmd --add-port=1338/udp
sudo firewall-cmd --permanent --add-port=1337/udp
sudo firewall-cmd --permanent --add-port=1338/udp
sudo firewall-cmd --reload

If needed:

sudo systemctl stop firewalld
sudo systemctl disable firewalld

iptables​

sudo iptables -L
sudo iptables -A INPUT -p udp --dport 1337 -j ACCEPT
sudo iptables -A INPUT -p udp --dport 1338 -j ACCEPT

You may temporarily stop the service or flush rules per your distribution.

Power-off due to packet loss​

Logs often show packet loss leading to power-off.

  • Some NICs (e.g. Intel I219-LM) are more loss-prone; try Realtek if possible.
  • Set network tolerance; common values 20–30; above 50 warrants a deeper network check.
robot.setRtNetworkTolerance(20, ec);
  • Check whether another wrapper shares port 1337 and causes congestion.

Protocol / network errors​

SDK reports protocol error (xCore minimum 2.3.0.0)​

Often the same class of issue: NIC buffering/forwarding delays real-time packets — verify NIC model and link stability.

Motion timeout / UDP open failure​

Upgrade to a verified build (e.g. 1124 or a newer trunk) to rule out fixed defects.

“Network connection” error​

realtime: Failed to create RT controller.network: network connection

Besides the network itself, check:

  • Tool/workobject frames are set correctly
  • Order of startMove / startLoop calls
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