Ran into something interesting. I've recently spent some time on a KRC4 (KSS 8.5) that uses EKI 3.0.3 to communicate with a "streaming" data system. The unique (for me) parts of this setup were that the protocol was UDP, and the robot was acting as a server, not a client. All the communications were being handled from inside the SPS, as well.
One of the issues I was asked to fix was that the "Alive" flag would not go False if the KLI cable was disconnected. The Channel XML file had no Ping setting, so I added one with a short delay, but that had an odd side effect: the Alive flag would never go True when I executed an EKI_OPEN. If I removed the Ping setting from the Channel file, everything worked as expected.
The EKI manual includes very little detail about the Ping, but if I had to guess, I'd say that Server mode and Ping interact negatively. Or, there's a trick to using them together that I haven't figured out.
I solved the problem by removing the Ping, and setting up an SPS element that monitors the Received flag and throws a fault if that flag doesn't change state for a few seconds. Since the remote system is sending data several times per second, this appears to work as intended so far. But I found the Server/Ping interaction curious enough to mention it (and hopefully help the next poor soul who encounters this).
Sadly, I don't have any more time with this robot to really dig in and experiment