TwinCAT 3 XAR runtime ADS 1861 timeout, what to check first?
I'm getting an ADS 1861 (0x745) timeout when trying to connect to a new TwinCAT 3 XAR runtime from my engineering environment. The request seems to leave my client, but the target never responds. What should I check first?
An ADS 1861 (0x745) timeout indicates that a request was sent to a remote terminal, but no response was received within the specified ADS timeout period. This often points to an issue with the remote terminal's configuration or the network path. The default ADS timeout is 5000 ms.
Likely causes and checks
1Route missing or one-sided on the remote target
- Points to it
- The client sent the request, but the target system does not have a correctly configured route to respond, or the route is only configured on one side. This is common with new or replaced targets.
- Check
- Verify that the ADS route exists on both the client (engineering environment) and the target (runtime environment) with the correct AMS NetId and IP address for each side.
2Firewall blocking ADS on the target
- Points to it
- Even if the target is reachable via ping, a firewall on the target system might be blocking the specific ports used by ADS, preventing the response from reaching the client.
- Check
- Ensure that incoming TCP port 48898 (and optionally UDP 48899 for search, TCP 8016 for Secure ADS) are allowed through the Windows firewall or any other firewall on the target system.
3Target or network too slow to answer within the timeout
- Points to it
- If the target system or the network path is under heavy load, or if the ADS requests are large or frequent, the response might not be able to return within the default 5000 ms timeout.
- Check
- Compare the size and rate of your ADS requests with the configured timeout. You can also trace the response time and check the task exceed counter on the target system to identify performance bottlenecks.
Next check: Start by confirming that the ADS route is correctly configured on both your engineering environment and the TwinCAT 3 XAR runtime target, ensuring the AMS NetId and IP addresses are accurate for both sides.
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