Connection loss with Rockwell's RSSQL interface

We've been having some intermittent connection loss/hang/timeout issues with PLCs on the production floor that cause significant downtime. PLCs communicate via RS Linx from what I'm told to a Rockwell Software RSSQL server (OPC server which ties a "tag" in the PLC to a field, procedure, etc in the database), which then translates that request and does the communication with Oracle via either OCI or ODBC. The database was 8i and is now 10g.

It seems the only thing we know for certain is the PLC isn't getting the "done" signal back from the RSSQL server so it just sits and waits. No explicit error messages appear anywhere. The RSSQL server is capable of knowing when a PL/SQL proc failed somehow, but that's not happening.

How can I prove without a doubt that the response from the Oracle server makes it to the RSSQL server? Both Oracle and RSSQL are running on Windows machines and neither are resource starved.

Perhaps a network (packet) sniffer is the only way to solve it? Are there any good free software-based ones? We don't have the budget for a hardware sniffer.

Peace,
Michael

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