Hi all As part of a review process to find the vendor and product line that best suits our needs, I am calling on the vast and broad knowledge of the listers to save hours of research and put together a short list of vendors who give more than lip service to the "O" word. We have been evaluating product lines but, this is extremely difficult as you normally have to dig quite deep before you discover the "gotchas" and hooks that loom large once you have bought into a PLC line. The criteria are somewhat subjective as we do a lot of integrating existing equipment and have been dismayed at how little interoperability and commonality exists. We do not see many of the advertised advantages of OTS PLC's as we are dealing with comms and data interchange and other areas where the current proprietary model is weakest by design. Who does the best job in the following areas: Interoperability: Supporting the most "foreign" protocols and providing tools to support the oddballs or create your own. This is for fieldbus and data connections. Who publishes their protocols? Third party support: Who works the best with independent I/O and components, for example Wago, Beckhoff Bus Terminal, etc.? Tools: We use Linux for comm. service, vision, bulk computation, and data conversion/processing. We currently use DOS based tools only because the alternative is Windows based tools with the particular vendor we are now using. As documented often on this list, Windows can be problematic in the areas of stability, communications and handling legacy environments. One positive trend we have noted is support for browser based interfacess. Has anyone advanced this to the point that you can use their products without the need for Windows? Is anyone hinting at Linux tools? SCADA: We currently run Cimplicity IU. It is reliable, robust, and no longer supported. The proposed replacements are not. What are the non-Windows alternatives? We are pressured by the non-support of the SCADA and the move towards "Windows only" programming tools. The Linux PLC will probably be the long term answer, but we need to find the most open environment in the meantime and there will always be needs that are best met by a PLC. I'm hoping that the list collectively knows just about everything available and can help navigate through the proprietary minefield. Thanks Curt Wuollet, Linux Systems Engineer Heartland Engineering Co.