Repeated 'Listen for Incoming Communication' on port 502 prevents connection to controller

Applies To:

SNAP-PAC-S1
SNAP-PAC-S2
SNAP-PAC-R1
SNAP-PAC-R2

Versions Affected:

Problem affects versions: R7.0a - R8.4a
Resolution is included beginning in version: B8.4b, build date 07/06/2009 and after
Problem is fixed in version: R8.5a

Resolved In Version:

Problem is fixed in version: R8.5a

Symptoms:

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).

Resolution:

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.

Questions?

Contact: Opto 22 Product Support.
Phone: 800-835-6786 or 951-695-3080
Email: support@opto22.com

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