PAC Control debug mode and PAC Manager cannot inspect a controller running a strategy that repeatedly calls the Listen for Incoming Communication command on registered TCP port 502. Continually calling this command causes the controller to eventually stop accepting new TCP connection requests on any TCP port.
The correct behavior for a strategy that calls this command on a TCP port which is already configured to listen, is to return an error -440. Instead, the brain returns 0 (success).
Continually calling the Listen for Incoming Communciation command on a port that is already configured to listen, eventually uses up resources that permit a connection. As a result, the brain cannot accept new TCP connection requests on any TCP port.
This problem has been fixed. The Listen for Incoming Communication command returns error -440 (instead of 0) when an attempt is made to listen on a port that is already in use. In addtion, the strategy logic should not repeatedly call this command on a port for which error -440 is returned.