Actually this issue is found in both version 1.4.9.398 and 1.03.341.398. But these versions are not reflected in the product version so I have selected which ever is latest!

In all these tests, test case is to create subscription but not to create the monitored item and wait for the keep alive message for publish request.

Tests started failing in the time of receiving the keep alive. When I check check with wireshark, I found that there is a problem in ctt test, which is expected keep alive message 1 publishing interval early.

Ex:
let us say publishing interval (revised) is 1000 ms
keep alive count (revised) is 5.

When Subscription created Subscription state is -> Normal

When Publish request sent, Immediately there is publish response for keep alive -> Subscription state is still continue to stay in Normal till publishing timer expires.

Clients sends the publish request, but there are no notification and after publishing interval timer expires, subscription state is changed from Normal to KeepAlive.

Not from here onwards, it takes 5 * 1000 ms to send the keep alive.

So, second keep alive will be sent at ==> 1000 ms (for publishing interval to expire) + 5 * 1000 ms ==> 6000 ms for the first time
later on, it will send the keep alive message (subscription state continue to stay in KeepAlive state) ==> 5000 ms.

This was working fine with 1.4.9.396 and 1.03.341.396 version. but in latest version I see the problem.

Please find the attached wireshark for details.